Bazel is a build system that emphasizes correctness and reproducibility of the build, speed of clean and incremental builds, and integration of the toolchain with IDEs and analysis tools. It is both a specification for code organization and a language for expressing software dependencies and the steps involved in a build.
Various aspects of the Bazel build system are described in other documents. The BUILD Concept Reference introduces the primary concepts of the Bazel build system; this is a place to start if you are new to Bazel. The Bazel BUILD Encyclopedia of Functions describes all the functions of the Bazel build language, including the syntax and semantics of the current build rules. Getting Started with BUILD files is a tutorial on how to write BUILD files.
Running the bazel
tool is easy. Simply go to your
workspace root and type bazel
.
(Bazel may also be invoked from the subdirectories of your
workspace.)
% bazel help Usage: bazel <command> <options> ... Available commands: analyze-profile Analyzes build profile data. build Builds the specified targets. canonicalize-flags Canonicalize Bazel flags. clean Removes output files and optionally stops the server. help Prints help for commands, or the index. info Displays runtime info about the Bazel server. query Executes a dependency graph query. run Runs the specified target. shutdown Stops the Bazel server. test Builds and runs the specified test targets. version Prints version information for Bazel. Getting more help: bazel help <command> Prints help and options for <command>. bazel help startup_options Options for the JVM hosting Bazel. bazel help target-syntax Explains the syntax for specifying targets. bazel help info-keys Displays a list of keys used by the info command.
The bazel
tool performs many functions, called
commands; users of Perforce, CVS and Subversion will be familiar
with this "Swiss army knife" arrangement. The most commonly used one is of
course bazel build
. You can browse the online help
messages using bazel help
. The links in the message
above refer to the relevant section of this document.
The Bazel system is implemented as a long-lived server process.
This allows it to perform many optimizations not possible with a
batch-oriented implementation, such as caching of BUILD files,
dependency graphs, and other metadata from one build to the
next. This improves the speed of incremental builds, and allows
different commands, such as build
and query
to share the same cache of loaded packages,
making queries very fast.
When you run bazel
, you're running the client. The
client finds the server based on the path of the workspace directory
and your userid, so if you build in multiple workspaces, you'll have
multiple Bazel server processes. Multiple users on the same
workstation can build concurrently in the same workspace. If the
client cannot find a running server instance, it starts a new one.
The server process will stop after a period of inactivity (3 hours,
by default).
For the most part, the fact that there is a server running is invisible to the user, but sometimes it helps to bear this in mind. For example, if you're running scripts that perform a lot of automated builds in different directories, it's important to ensure that you don't accumulate a lot of idle servers; you can do this by explicitly shutting them down when you're finished with them, or by specifying a short timeout period.
The name of a Bazel server process appears in the output of ps
x
or ps -e f
as
bazel(dirname)
, where dirname is the
basename of the directory enclosing the root of the Bazel
workspace. For example:
% ps -e f 16143 ? Sl 3:00 bazel(src-jrluser2) -server -Djava.library.path=...
This makes it easier to find out which server process belongs to a
given workspace. (Beware that with certain other options
to ps
, Bazel server processes may be named just
java
.) Bazel servers can be stopped using
the shutdown command.
In some cases, such as in continuous builds, it may be desirable to disable
client/server mode and instead run Bazel as a batch application.
See the --batch
switch below.
.bazelrc
, the Bazel configuration file,
the --bazelrc=file
option, and the
--config=value
option
Bazel accepts many options. Typically, some of these are varied
frequently (e.g. --subcommands
) while others stay the
same across several builds (e.g. --package_path
).
To avoid having to specify these constant options every time you do
a build or run some other Bazel command, Bazel allows you to
specify options in a configuration file.
Bazel looks for an optional configuration file in the location
specified by the --bazelrc=file
option. If
this option is not specified then, by default, Bazel looks for the
file called .bazelrc
in one of two directories: first,
in the workspace root directory, then in your home directory. If
it finds a file in the first (workspace-specific) location, it will
not look at the second (global) location.
The --bazelrc=file
option must
appear before the command name (e.g. build
),
and must use the =
syntax—a space is not allowed.
The option --bazelrc=/dev/null
effectively disables the
use of a configuration file. We strongly recommend that you use
this option when performing release builds, or automated tests that
invoke Bazel.
Aside from the configuration file described above, Bazel also looks
for a master configuration file next to the binary. The name of this
file is the same as the name of the binary with the
string .bazelrc
attached. This file is not intended to
be user-modifiable; its purpose is for the Bazel team to be able to
turn experimental features on or off immediately without releasing a
new Bazel version, should an urgent need arise. Reading of this file
can be disabled using the --nomaster_bazelrc
option.
Like all UNIX "rc" files, the .bazelrc
file is a text
file with a line-based grammar. Lines starting #
are
considered comments and are ignored, as are blank lines. Each line
contains a sequence of words, which are tokenized according to the
same rules as the Bourne shell.
The first word on each line is the name of a Bazel command, such
as build
or query
. The remaining words
are the default options that apply to that command.
More than one line may be used for a command; the options are combined
as if they had appeared on a single line.
(Users of CVS, another tool with a "Swiss army knife" command-line
interface, will find the syntax familiar to that of .cvsrc
.)
Startup options may be specified in the
.bazelrc
file using the command startup
.
These options are described in the interactive help
at bazel help startup_options
.
Options specified in the command line always take precedence over
those from a configuration file, and options in the user-specific
configuration file always take precedence over the master one.
Options may include words other than flags, such as the names of
build targets, etc; these are always prepended to the explicit
argument list provided on the command-line, if any.
Common command options may be specified in the
.bazelrc
file using the command common
.
In addition, commands may have :name
suffixes. These
options are ignored by default, but can be pulled in through the
--config=name
option, either on the command line or in
a .bazelrc
file. The intention is that these bundle command line
options that are commonly used together, for example
--config=releasemode
.
The command named import
is special: if Bazel encounters such
a line in a .bazelrc
file, it parses the contents of the file
referenced by the import statement, too. Options specified in an imported file
take precedence over ones specified before the import statement, options
specified after the import statement take precedence over the ones in the
imported file, and options in files imported later take precedence over files
imported earlier.
Here's an example ~/.bazelrc
file:
# Bob's Bazel option defaults startup --batch --host_jvm_args=-XX:-UseParallelGC import /home/bobs_project/bazelrc build --package_path %workspace%:/home/bob/stuff/bazel --keep_going --jobs 600 build --color=yes query --keep_going build:releasemode --define buildtype="Release" --test_timeout=3600
The most important function of Bazel is, of course, building code. Type
bazel build
followed by the name of the
target you wish to build. Here's a typical
session:
% bazel build //foo Welcome to Bazel ____Loading package: foo ____Loading package: bar ____Loading package: baz ____Loading complete. Analyzing... ____Building 1 target... ____[0%] Executing Genrule //bar:helper_rule ____[10%] Executing Genrule //baz:another_helper_rule ____[95%] Building foo/foo.jar Target //foo:foo up-to-date: bazel-bin/foo/foo.jar bazel-bin/foo/foo ____Elapsed time: 9.905s
Bazel prints a welcome message, followed by progress messages as it loads all the packages in the transitive closure of dependencies of the requested target and analyzes them for correctness, then executes the compilers and other tools of the build.
Bazel prints progress messages during the execution phase of the build, showing the current build step that is being started, and approximately what fraction of the build is complete. If the estimate of the total workload includes steps that are already up-to-date, progress will advance rapidly when this is discovered. Since progress is reported when steps are started, rather than completed, the reported progress will never reach 100%, and, if multiple steps are started with no intervening completions, the reported progress will not change.
At the end of the build Bazel
prints which targets were requested, whether or not they were
successfully built, and if so, where the output files can be found.
Scripts that run builds can reliably parse this output; see --show_result
for more
details.
Typing the same command again:
% bazel build //foo Welcome to Bazel ____Loading complete. Analyzing... ____Building 1 target... Target //foo:foo up-to-date: bazel-bin/foo/foo.jar bazel-bin/base/foo ____Elapsed time: 0.280s
we see an incremental build: in this case, there are no packages to re-load, since nothing has changed, and no build steps to execute. In most cases, this results in dramatically faster output time.
Before you can start a build, you will need a Bazel workspace. This is simply a directory tree that contains all the source files needed to build your application. Bazel allows you to perform a build from a completely read-only volume.
--package_path
Bazel finds its packages by searching the package path. This is a colon separated ordered list of bazel directories, each being the root of a partial source tree.
To specify a custom package path using the
--package_path
option:
% bazel build --package_path %workspace%:/some/other/root
Package path elements may be specified in three formats:
/
, the path is absolute.
%workspace%
, the path is taken relative
to the nearest enclosing bazel directory./home/bob/clients/bob_client/bazel/foo
, then the
string %workspace%
in the package-path is expanded
to /home/bob/clients/bob_client/bazel
.
.
,
and then cd into the directory
/home/bob/clients/bob_client/bazel/foo
, packages
will be resolved from the
/home/bob/clients/bob_client/bazel/foo
directory.
If you use a non-default package path, we recommend that you specify it in your Bazel configuration file for convenience.
Bazel doesn't require any packages to be in the current directory, so you can do a build from an empty bazel workspace if all the necessary packages can be found somewhere else on the package path.
Example: Building from an empty client
% mkdir -p foo/bazel % cd foo/bazel % bazel build --package_path /some/other/path //foo
Bazel allows a number of ways to specify the targets to be built. Collectively, these are known as target patterns. The on-line help displays a summary of supported patterns:
% bazel help target-syntax Target pattern syntax ===================== The Bazel label syntax (as used in BUILD files) is used to specify a single target. Bazel target patterns generalize this syntax to sets of targets, and also support working directory-relative forms, recursion, subtraction and filtering. Examples: Specifying a single target: //foo/bar:wiz The single target '//foo/bar:wiz'. foo/bar/wiz Equivalent to the first existing one of these: //foo/bar:wiz //foo:bar/wiz //foo/bar Equivalent to '//foo/bar:bar'. Specifying all rules in a package: //foo/bar:all Matches all rules in package 'foo/bar'. Specifying all rules recursively beneath a package: //foo/...:all Matches all rules in all packages beneath directory 'foo'. //foo/... (ditto) Working-directory relative forms: (assume cwd = 'bazel/foo') Target patterns which do not begin with '//' are taken relative to the working directory. Patterns which begin with '//' are always absolute. ...:all Equivalent to '//foo/...:all'. ... (ditto) bar/...:all Equivalent to '//foo/bar/...:all'. bar/... (ditto) bar:wiz Equivalent to '//foo/bar:wiz'. :foo Equivalent to '//foo:foo'. bar:all Equivalent to '//foo/bar:all'. :all Equivalent to '//foo:all'. Note: The "..." (recursive) syntax does not follow directory symlinks. Summary of target wildcards: :all, Match all rules in the specified packages. :*, :all-targets Match all targets (rules and files) in the specified packages, including .par and _deploy.jar files. Subtractive patterns: Target patterns may be preceded by '-', meaning they should be subtracted from the set of targets accumulated by preceding patterns. For example: % bazel build -- bigtable/... -bigtable/contrib/... builds everything in 'bigtable', except 'contrib'. As usual, the '--' is required to prevent '-b' from being interpreted as an option.
Whereas Bazel labels are used to specify individual targets, e.g. for declaring dependencies in BUILD files, Bazel's target patterns are a syntax for specifying multiple targets: they are a generalization of the label syntax for sets of targets, using wildcards. In the simplest case, any valid label is also a valid target pattern, identifying a set of exactly one target.
foo/...
is a wildcard over packages,
indicating all packages recursively beneath
directory foo
(for all roots of the package
path). :all
(or :all-rules
) is a wildcard
over targets, matching all rules within a package. These two may be
combined, as in foo/...:all
, and when both wildcards
are used, this may be abbreviated to foo/...
.
In addition, :*
(or :all-targets
) is a
wildcard that matches every target in the matched packages,
including files that aren't normally built by any rule, such
as _deploy.jar
files associated
with java_binary
rules and .par
files
associated with py_binary
rules.
This implies that :*
denotes a superset
of :all
; while potentially confusing, this syntax does
allow the familiar :all
wildcard to be used for
typical builds, in which the building of _deploy.jar
and .par
targets is not desired.
In addition, Bazel allows a slash to be used instead of the colon
required by the label syntax; this is often convenient when using
Bash filename expansion. For example, foo/bar/wiz
is
equivalent to //foo/bar:wiz
(if there is a
package foo/bar
) or to //foo:bar/wiz
(if
there is a package foo
).
Many Bazel commands accept a list of target patterns as arguments,
and they all honor the prefix negation operator `-
'.
This can be used to subtract a set of targets from the set specified
by the preceding arguments. For example,
bazel build foo/... bar/...
means "build all
targets beneath foo
and all targets
beneath bar
", whereas
bazel build -- foo/... -foo/baz/...
means "build all targets beneath foo
except
those beneath foo/baz
".
(The --
argument is required to prevent the subsequent
arguments starting with -
from being interpreted as
additional options.)
Targets with obsolete=1
or tags=["manual"]
will
be ignored by all command line wildcards (..., :*, :all, etc). The only
way to run such targets is to specify them explicitly on the command line.
If you use Bash, and source /etc/bash_completion,
Bash's command-completion is augmented to understand Bazel's
options, command set, and target syntax. For example,
hitting TAB
after typing a package name followed by a
colon will expand the names of rules defined in that package:
% source /etc/bash_completion % bazel build bar:<TAB> aardvark alpha chestnut walnut ... % bazel build bar:a<TAB> aardvark alpha % bazel build bar:al<TAB> % bazel build bar:alpha
Similarly, hitting TAB
after bazel
test package:
will expand the names of just
the test rules in that package.
The completion script will additionally attempt to
expand --key=value
options too.
One of the primary goals of the Bazel project is to ensure correct incremental rebuilds. Previous build tools, especially those based on Make, make several unsound assumptions in their implementation of incremental builds.
Firstly, that timestamps of files increase monotonically. While this is the typical case, it is very easy to fall afoul of this assumption; syncing to an earlier revision of a file causes that file's modification time to decrease; Make-based systems will not rebuild. A similar situation may arise when switching to a source-control view of an earlier milestone.
More generally, while Make detects changes to files, it does
not detect changes to commands. If you alter the options passed to
the compiler in a given build step, Make will not re-run the
compiler, and it is necessary to manually discard the invalid
outputs of the previous build using make clean
.
Also, Make is not robust against the unsuccessful termination of one of its subprocesses after that subprocess has started writing to its output file. While the current execution of Make will fail, the subsequent invocation of Make will blindly assume that the truncated output file is valid (because it is newer than its inputs), and it will not be rebuilt. Similarly, if the Make process is killed, a similar situation can occur.
Bazel avoids these assumptions, and others. Bazel maintains a database of all work previously done, and will only omit a build step if it finds that the set of input files (and their timestamps) to that build step, and the compilation command for that build step, exactly match one in the database, and, that the set of output files (and their timestamps) for the database entry exactly match the timestamps of the files on disk. Any change to the input files or output files, or to the command itself, will cause re-execution of the build step.
The benefit to users of correct incremental builds is: less time
wasted due to confusion. (Also, less time spent waiting for
rebuilds caused by use of make clean
, whether necessary
or pre-emptive.)
Formally, we define the state of a build as consistent when all the expected output files exist, and their contents are correct, as specified by the steps or rules required to create them. When you edit a source file, the state of the build is said to be inconsistent, and remains inconsistent until you next run the build tool to successful completion. We describe this situation as unstable inconsistency, because it is only temporary, and consistency is restored by running the build tool.
There is another kind of inconsistency that is pernicious: stable
inconsistency. If the build reaches a stable inconsistent
state, then repeated successful invocation of the build tool does
not restore consistency: the build has gotten "stuck", and the
outputs remain incorrect. Stable inconsistent states are the main
reason why users of Make (and other build tools) type make
clean
. Discovering that the build tool has failed in this
manner (and then recovering from it) can be time consuming and very
frustrating.
Conceptually, the simplest way to achieve a consistent build is to throw away all the previous build outputs and start again: make every build a clean build. This approach is obviously too time-consuming to be practical (except perhaps for release engineers), and therefore to be useful, the build tool must be able to perform incremental builds without compromising consistency.
Correct incremental dependency analysis is hard, and as described above, many other build tools do a poor job of avoiding stable inconsistent states during incremental builds. In contrast, Bazel offers the following guarantee: after a successful invocation of the build tool during which you made no edits, the build will be in a consistent state. (If you edit your source files during a build, Bazel makes no guarantee about the consistency of the result of the current build. But it does guarantee that the results of the next build will restore consistency.)
As with all guarantees, there comes some fine print: there are some known ways of getting into a stable inconsistent state with Bazel. We won't guarantee to investigate such problems arising from deliberate attempts to find bugs in the incremental dependency analysis, but we will investigate and do our best to fix all stable inconsistent states arising from normal or "reasonable" use of the build tool.
bazel clean
Bazel has a clean
command, analogous to that of Make.
It deletes the output directories for all build configurations performed
by this Bazel instance, or the entire working tree created by this
Bazel instance, and resets internal caches. If executed without any
command-line options, then the output directory for all configurations
will be cleaned.
To completely remove the entire working tree created by a Bazel
instance, you can specify the --expunge
option. When
executed with --expunge
, the clean command simply
removes the entire output base tree which, in addition to the build
output, contains all temp files created by Bazel. It also
stops the Bazel server after the clean, equivalent to the shutdown
command. For example, to
clean up all disk and memory traces of a Bazel instance, you could
specify:
% bazel clean --expunge
Alternatively, you can expunge in the background by using
--expunge_async
. It is safe to invoke a Bazel command
in the same client while the asynchronous expunge continues to run.
Note, however, that this may introduce IO contention.
The clean
command is provided primarily as a means of
reclaiming disk space for workspaces that are no longer needed.
However, we recognize that Bazel's incremental rebuilds are not
perfect;
clean
may be used to recover a consistent
state when problems arise.
Bazel's design is such that these problems are fixable; we consider
such bugs a high priority, and will do our best fix them.
We encourage developers to get out of the habit of
using clean
and into that of reporting bugs in the
tools.
In Bazel, a build occurs in three distinct phases; as a user, understanding the difference between them provides insight into the options which control a build (see below).
The first is loading during which all the necessary BUILD files for the initial targets, and their transitive closure of dependencies, are loaded, parsed, evaluated and cached.
For the first build after a Bazel server is started, the loading phase can take many seconds if many BUILD files are loaded from high-latency / remotely hosted filesystems. In subsequent builds, especially if no BUILD files have changed, loading occurs very quickly.
Errors reported during this phase include: package not found, target not found, lexical and grammatical errors in a BUILD file, and evaluation errors.
The second phase, analysis, involves the semantic analysis and validation of each build rule, the construction of a build dependency graph, and the determination of exactly what work is to be done in each step of the build.
Like loading, analysis also takes several seconds when computed in
its entirety. However, Bazel can cache the dependency graph from
one build to the next, as an optimization;
see --cache_analysis
).
This option makes this step extremely fast in the case where the
packages haven't changed since the previous build.
Errors reported at this stage include: inappropriate dependencies, invalid inputs to a rule, and all rule-specific error messages.
The loading and analysis phases are generally very vast; this is partly because Bazel avoids unnecessary file I/O at this stage, reading only BUILD files in order to determine the work to be done. This is by design, and makes Bazel a good foundation for analysis tools, such as Bazel's query command, which is implemented atop the loading phase.
The third and final phase of the build is execution. This phase ensures that the outputs of each step in the build are consistent with its inputs, re-running external compilation tools as necessary. This step is where the build spends the majority of its time, ranging from a few seconds to over an hour for a large build. Errors reported during this phase include: missing source files, errors in an external compilation tool, or failure of a tool to produce the expected set of outputs.
The following sections describe the options available during a
build. When --long
is used on a help command, the on-line
help messages provide summary information about the meaning, type and
default value for each option.
Most options can only be specified once. When specified multiple times, the last instance wins. Options that can be specified multiple times are identified in the on-line help with the text 'may be used multiple times'.
See also the --show_package_location
option.
--package_path
This option specifies the set of directories that are searched to find the BUILD file for a given package; see Setting up a Bazel workspace above for a complete explanation.
--deleted_packages
This option specifies a comma-separated list of packages which Bazel should consider deleted, and not attempt to load from any directory on the package path.
if you use a workspace layout that maps the entire source tree into some readonly path while mapping writable subsections into another path, you may need to use this option to solve the following problem: when you have a pending deletion of a package in your Bazel workspace, but there is still a BUILD file for this package somewhere on your package path, Bazel will consider the package existent unless this option tells it not to.
Consider the following scenario: you have two
packages, x
and x/y
(a subpackage). When
you populate your client, both packages exist beneath both
package-path roots:
~/src/$WORKSPACE_WRITABLE_ROOT/ /x/BUILD /x/y/BUILD <-- about to delete this /x/y/foo.txt ~/src/$WORKSPACE_READONLY_ROOT/ /x/BUILD /x/y/BUILD /x/y/foo.txt
Now you delete ~/src/$WORKSPACE_WRITABLE_ROOT/x/y/BUILD
, intending to
merge the contents of package x/y
into x
,
and now when x's BUILD file refers to the
file x/y/foo.txt
, it uses the
label //x:y/txt
.
However, x/y may have been deleted in the read/write workspace, but the
package still exists elsewhere on the package-path. In this situation, Bazel
will issue an error, saying that //x:y/txt
is an invalid label
because package x/y
still exists (beneath $WORKSPACE_READONLY_ROOT
).
The solution is to specify --deleted_packages x/y
.
These options control Bazel's error-checking and/or warnings.
--check_constraint constraint
This option takes an argument that specifies which constraint should be checked.
Bazel performs special checks on each rule that is annotated with the given constraint.
The supported constraints and their checks are as follows:
public
: Verify that all java_libraries marked with
constraints = ['public']
only depend on java_libraries
that are marked as constraints = ['public']
too. If Bazel
finds a dependency that does not conform to this rule, Bazel will issue
an error.
--[no]check_licenses
This option causes Bazel to analyze the licenses
and
distribs
clauses in BUILD files to identify uses of third
party code that are incompatible with how a product is going to be
distributed.
% bazel build --check_licenses //foo:bar
will check the licensing of all packages used by "//foo:bar", to ensure that they are compatible with how bar is distributed. If the licensing check finds no errors, then bar will be built.
--[no]check_visibility
If this option is set to false, visibility checks are demoted to warnings. The default value of this option is true, so that by default, visibility checking is done.
--output_filter regex
The --output_filter
option will only show build and compilation
warnings for targets that match the regular expression. If a target does not
match the given regular expression and its execution succeeds, its standard
output and standard error are thrown away. This option is intended to be used
to help focus efforts on fixing warnings in packages under development. Here
are some typical values for this option:
--output_filter= |
Show all output. |
--output_filter='^//(first/project|second/project):' |
Show the output for the specified packages. |
--output_filter=DONT_MATCH_ANYTHING |
Don't show output. |
If this option is not given, a default filter will be created according to the
--auto_output_filter
option.
--auto_output_filter (none|packages|subpackages)
If no --output_filter
option is
given, Bazel creates an output filter from the targets listed on the command
line:
none
does no filtering and shows all output.
packages
shows only the output for the packages of targets
requested on the command line. For example, the Bazel invocation
% bazel build //foo:bar //baz/...will show the output for all targets in the package
foo
or any
package under baz
. Warnings for dependencies in other packages
will be hidden.
subpackages
(the default) works similar
to packages
but also includes output from subpackages.
--[no]analysis_warnings_as_errors
When this option is enabled, visible analysis warnings (as specified by the output filter) are treated as errors, effectively preventing the build phase from starting. This feature can be used to enable strict builds that do not allow new warnings to creep into a project.
These options control which options Bazel will pass to other tools.
--jvmopt jvm-option
This option allows option arguments to be passed to the Java VM. It can be used with one big argument, or multiple times with individual arguments. For example:
% bazel build --jvmopt="-server -Xms256m" java/com/myorg/foo/bar:all
will use the server VM for launching all Java binaries and set the startup heap size for the VM to 256 MB.
--javacopt javac-option
This option allows option arguments to be passed to javac. It can be used with one big argument, or multiple times with individual arguments. For example:
% bazel build --javacopt="-g:source,lines" //myprojects:prog
will rebuild a java_binary with the javac default debug info (instead of the Bazel default).
The option is passed to javac after the Bazel built-in default options for javac and before the per-rule options. The last specification of any option to javac wins. The default options for javac are:
-g -source 7 -target 7 -encoding UTF-8 -Xlint:all,-serial,-processing,-fallthrough,-deprecation,-sunapi,-rawtypes,-try,-cast,-varargs,-finally,-static,-dep-ann,-overrides,-unchecked -Werror:+divzero,+empty
Note that changing --javacopt
settings will force a recompilation
of all affected classes. Also note that javacopts parameters listed in
specific java_library or java_binary build rules will be placed on the javac
command line after these options.
-Werror:(+|-)warning[,(+|-)warning]*
This javac option enables selective treating of warnings as errors. To specify
all or none of the warnings, use +all
or -all
.
The last specification for any warning wins. A typical value that enables all
warnings as errors except those that may be caused upstream is:
-Werror:+all,-deprecation,-unchecked
The divzero and empty javac warnings are promoted to errors by default. These
errors cannot be disabled from the Bazel command line or the BUILD file.
However, in extreme cases they may be disabled by adding a
@SuppressWarnings({"divzero", "empty"})
annotation to your Java
source.
-extra_checks[:(off|on)]
This javac option enables extra correctness checks. Any problems found will
be presented as errors.
Either -extra_checks
or -extra_checks:on
may be used
to force the checks to be turned on. -extra_checks:off
completely
disables the analysis.
When this option is not specified, the default behavior is used.
--strict_java_deps
(default|strict|off|warn|error)
This option controls whether javac checks for missing direct dependencies. Java targets must explicitly declare all directly used targets as dependencies. This flag instructs javac to determine the jars actually used for type checking each java file, and warn/error if they are not the output of a direct dependency of the current target.
off
means checking is disabled.
warn
means javac will generate standard java warnings of
type [strict]
for each missing direct dependency.
default
, strict
and error
all
mean javac will generate errors instead of warnings, causing the current
target to fail to build if any missing direct dependencies are found.
This is also the default behavior when the flag is unspecified.
--javawarn (all|cast|deprecation|empty|unchecked|fallthrough|path|rawtypes|serial|finally|overrides)
This option is used to enable Java warnings across an entire build. It takes an argument which is a javac warning to be enabled, overriding any other Java options that disable the given warning. The arguments to this option are appended to the "-Xlint:" flag to javac, and must be exactly one of the listed warnings.
For example:
% bazel build --javawarn="deprecation" --javawarn="unchecked" //java/...
Note that changing --javawarn
settings will force a recompilation
of all affected classes.
These options affect the build commands and/or the output file contents.
--java_cpu cpu
This option specifies the name of the CPU architecture that should be used to build libraries dynamically loaded by the JVM.
--android_cpu cpu
This option specifies the name of the CPU architecture that should be used to build libraries dynamically loaded by the Android applications.
--define name=value
This option takes an argument which is a variable
definition of the form "name=value". The defined variable is integrated
into the build environment as if they were declared in the BUILD file
using a vardef
statement. This option can occur multiple times
on the command-line. If the same variable is declared more than once, the
last definition is the one which is used.
% bazel build --define "INCLUDE_X=1" --define "LINK_Y=no" foo:bar
will build target "foo:bar", and all its prerequisites, with the
variable assignments INCLUDE_X=1
,
and LINK_Y=no
in the "Make" environment.
Definitions specified in this way are global: they apply to all
packages. The order of precedence for definitions of "Make"
variables, highest first, is: --define
k=...
, vardef('k',
...)
, then the global defaults.
--[no]translations
The --notranslations
option can be used to disable the bundling
of translated Java messages into the jar for each affected rule. By default,
Bazel will locate the Java message translations on the package path using the
targets defined by
--message_translations
and use the resulting files for
translating the messages for each java_library
. If no
targets are specified, Bazel does not bundle translations.
--message_translations
translation-targets
This option specifies the targets containing the Java message translations. These targets are used to find the Java message translations for each locale. This option can be used multiple times to specify a list of translations. The targets are specified using standard label syntax. Rules that output directories, such as Fileset and misbehaving genrules, cannot be used with this flag.
Typically translations will increase build times significantly.
% bazel build \ --message_translations=//some/package/client:translations \ --message_translations=//some/package/server:translations \ java/com/myorg/myapp:Myapp_deploy.jar
will build the Myapp_deploy.jar
including
translations. The translations will be retrieved from the
project-specific translations in
//some/package/client:translations
and
//some/package/server:translations
--android_sdk version
This option specifies the version of the Android SDK/platform toolchain and Android runtime library that will be used to build any Android-related rule.
--java_langtools label
This option specifies the label of the Java langtools jar (used by Java compilation tools).
--javabase path
This option specifies the value of the JAVABASE
"Make" variable
which is passed to all subprocesses (e.g. external Java programs)
during a build.
This does not select the Java compiler that is used to compile Java
source files. There is currently no way to do that, but you can use
--javacopt="-source 5 -target 5"
(for example) to
select a different version of the source language (Java) or target
language (JVM) during compilation.
--javac_bootclasspath label
This option specifies the label of the bootclasspath that should be used by the Java compiler. This lets you compile against different versions of the Java class library, for example, version 7 instead of version 6.
These options affect how Bazel will execute the build. They should not have any significant effect on the output files generated by the build. Typically their main effect is on the speed on the build.
--jobs n
(-j)This option, which takes an integer argument, specifies a limit on the number of jobs that should be executed concurrently during the execution phase of the build. The default is 200.
Setting this to -1 means "no limit": use as many threads as possible.
Note that the number of concurrent jobs that Bazel will run
is determined not only by the --jobs
setting, but also
by Bazel's scheduler, which tries to avoid running concurrent jobs
that will use up more resources (RAM or CPU) than are available,
based on some (very crude) estimates of the resource consumption
of each job. The behavior of the scheduler can be controlled by
the --ram_utilization_factor
option.
--progress_report_interval n
Bazel periodically prints a progress report on jobs that are not
finished yet (e.g. long running tests). This option sets the
reporting frequency, progress will be printed every n
seconds.
The default is 0, that means an incremental algorithm: the first report will be printed after 10 seconds, then 30 seconds and after that progress is reported once every minute.
--ram_utilization_factor
percentageThis option, which takes an integer argument, specifies what percentage of the system's RAM Bazel should try to use for its subprocesses. This option affects how many processes Bazel will try to run in parallel. The default value is 67. If you run several Bazel builds in parallel, using a lower value for this option may avoid thrashing and thus improve overall throughput. Using a value higher than the default is NOT recommended. Note that Bazel's estimates are very coarse, so the actual RAM usage may be much higher or much lower than specified. Note also that this option does not affect the amount of memory that the Bazel server itself will use.
This option has no effect if --resource_autosense is enabled.
--local_resources
availableRAM,availableCPU,availableIOThis option, which takes three comma-separated floating point arguments, specifies the amount of local resources that Bazel can take into consideration when scheduling build and test activities. Option expects amount of available RAM (in MB), number of CPU cores (with 1.0 representing single full core) and workstation I/O capability (with 1.0 representing average workstation). By default Bazel will estimate amount of RAM and number of CPU cores directly from system configuration and will assume 1.0 I/O resource.
If this option is used, Bazel will ignore both --ram_utilization_factor and --resource_autosense options.
--[no]build_runfile_links
This option, which is currently enabled by default, specifies
whether the runfiles symlinks for tests
should be built on the local
machine. Using --nobuild_runfile_links
can be useful
to validate if all targets build without incurring the overhead
for building the runfiles trees.Within Bazel's output tree, the
runfiles symlink tree is typically rooted as a sibling of the corresponding
binary or test.
When Bazel tests are executed, their
run-time data dependencies are gathered together in one place, and
may be accessed by the test using paths of the form
$TEST_SRCDIR/bazel/packagename/filename
.
The "runfiles" tree ensures that tests have access to all the files
upon which they have a declared dependence, and nothing more. By
default, the runfiles tree is implemented by constructing a set of
symbolic links to the required files. As the set of links grows, so
does the cost of this operation, and for some large builds it can
contribute significantly to overall build time, particularly because
each individual test requires its own runfiles tree.
--[no]cache_analysis
This option enables an optimization: caching of the results of the
analysis phase from one build to the next. The dependency graph
from the previous build will be re-used if no build packages have
been re-loaded due to changes, and no configuration options have
changed.
The optimization is enabled by default, but can be disabled
via --nocache_analysis
; this may be useful during fault
isolation.
Typically, this option speeds up the analysis phase by a factor of at least a hundred, making analysis time a negligible fraction of total build time.
--[no]discard_analysis_cache
When this option is enabled, Bazel will discard the analysis cache right before execution starts, thus freeing up additional memory (around 10%) for the execution phase. The drawback is that further incremental builds will be slower.
--[no]keep_going
(-k)As in GNU Make, the execution phase of a build stops when the first error is encountered. Sometimes it is useful to try to build as much as possible even in the face of errors. This option enables that behavior, and when it is specified, the build will attempt to build every target whose prerequisites were successfully built, but will ignore errors.
While this option is usually associated with the execution phase of
a build, it also effects the analysis phase: if several targets are
specified in a build command, but only some of them can be
successfully analyzed, the build will stop with an error
unless --keep_going
is specified, in which case the
build will proceed to the execution phase, but only for the targets
that were successfully analyzed.
--[no]resource_autosense
Bazel's default scheduling algorithm is based on fixed estimates of the available CPU/memory resources of the workstation. It does not account for the load of any unrelated jobs that happen to be running on your machine, such as another Bazel build in a different workspace.
The --resource_autosense
option enables a different
scheduling algorithm for the execution of build steps. It causes
Bazel to poll the system CPU load and available memory periodically.
This data is used to limit the number of commands executed
simultaneously on the workstation, ensuring that the system remains
responsive, especially when other jobs are running on the machine.
(Note, neither algorithm takes into account the actual (dynamic) cost of each build step.)
These options determine what to build or test.
--[no]build
This option causes the execution phase of the build to occur; it is on by default. When it is switched off, the execution phase is skipped, and only the first two phases, loading and analysis, occur.
This option can be useful for validating BUILD files and detecting errors in the inputs, without actually building anything.
--[no]build_tests_only
If specified, Bazel will build only what is necessary to run the *_test
and test_suite rules that were not filtered due to their
size,
timeout,
tag, or
language.
If specified, Bazel will ignore other targets specified on the command line.
By default, this option is disabled and Bazel will build everything
requested, including *_test and test_suite rules that are filtered out from
testing. This is useful because running
bazel test --build_tests_only foo/...
may not detect all build
breakages in the foo
tree.
--[no]compile_only
This option forces Bazel to execute only "lightweight" compilation steps
related to the specified targets. At this time such steps only include
compilation of sources for java_*
rules
without building dependencies.
This option can be useful to quickly validate a given Java target for
compilation errors. In particular, it might be especially useful when
specified together with the
--compile_one_dependency
option.
--[no]compilation_prerequisites_only
Given this option, Bazel will only build files that are prerequisites for compilation of the given target (for example, generated source files), but will not build the target itself.
This option can be useful to quickly validate a given Java target for
compilation errors. In particular, it might be especially useful when
specified together with the
--compile_one_dependency
option.
--[no]check_up_to_date
This option causes Bazel not to perform a build, but merely check whether all specified targets are up-to-date. If so, the build completes successfully, as usual. However, if any files are out of date, instead of being built, an error is reported and the build fails. This option may be useful to determine whether a build has been performed more recently than a source edit (e.g. for pre-submit checks) without incurring the cost of a build.
See also --check_tests_up_to_date
.
--[no]compile_one_dependency
Compile a single dependency of the argument files. This is useful for syntax checking source files in IDEs, for example, by rebuilding a single target that depends on the source file to detect errors as early as possible in the edit/build/test cycle. This argument affects the way all non-flag arguments are interpreted: for each source filename, one rule that depends on it will be built. Rules in the same language space are preferentially chosen. For multiple rules with the same preference, the one that appears first in the BUILD file is chosen. An explicitly named target pattern which does not reference a source file results in an error.
--[no]source_jars
By default, this option is disabled. If enabled, Bazel will also build all source jars in the transitive closure of the targets specified on the command line.
--test_size_filters size[,size]*
If specified, Bazel will test (or build if --build_tests_only
is also specified) only test targets with the given size. Test size filter
is specified as comma delimited list of allowed test size values (small,
medium, large or enormous), optionally preceded with '-' sign used to denote
excluded test sizes. For example,
% bazel test --test_size_filters=small,medium //foo:alland
% bazel test --test_size_filters=-large,-enormous //foo:all
will test only small and medium tests inside //foo.
By default, test size filtering is not applied.
--test_timeout_filters timeout[,timeout]*
If specified, Bazel will test (or build if --build_tests_only
is also specified) only test targets with the given timeout. Test timeout filter
is specified as comma delimited list of allowed test timeout values (short,
moderate, long or eternal), optionally preceded with '-' sign used to denote
excluded test timeouts. See --test_size_filters
for example syntax.
By default, test timeout filtering is not applied.
--test_tag_filters tag[,tag]*
If specified, Bazel will test (or build if --build_tests_only
is also specified) only test targets that have at least one required tag
(if any of them are specified) and does not have any excluded tags. Test tag
filter is specified as comma delimited list of tag keywords, optionally
preceded with '-' sign used to denote excluded tags. Required tags may also
have a preceding '+' sign.
For example,
% bazel test --test_tag_filters=performance,stress,-flaky //myproject:all
will test targets that are tagged with either performance
or
stress
tag but are not tagged with the flaky
tag.
By default, test tag filtering is not applied. Note that you can also filter
on test's size
and local
tags in
this manner.
--test_filter=filter-expression
Specifies a filter that the test runner may use to pick a subset of tests for running. All targets specified in the invocation are built, but depending on the expression only some of them may be executed; in some cases, only certain test methods are run.
The particular interpretation of filter-expression is up to
the test framework responsible for running the test. It may be a glob,
substring, or regexp. --test_filter
is a convenience
over passing different --test_arg
filter arguments,
but not all frameworks support it.
Examples:
:my_junit3_test --test_filter=com.myorg.myproj.MyClass#testMyStuff # class or method (multiple # values OK, separate w/commas) :my_junit4_test --test_filter=Frob.*ate # regexp
--dump_makefile
If this option is specified, Bazel will dump a representation
of the action graph for the current build request in (pseudo)
make
syntax to the file Makefile.bazel
in the execution root directory.
This is for debugging purposes only. The format of the output file might change in future Bazel releases.
--dump_action_graph
If this option is specified, Bazel will dump a representation of the action graph for the current build request in GraphViz syntax to the file 'BazelActionGraph.dot' in the workspace root.
This is for debugging purposes only. The format of the output file might change in future Bazel releases.
--dump_action_graph_for_package=package
This option restricts the parts shown in an action graph to the given packages.
This is only useful in conjunction with specifying --dump_action_graph
.
--dump_action_graph_with_middlemen
This flag selects whether middlemen are shown in an action graph or not. Middlemen could be
considered an implementation detail and tend to make graphs much larger.
This is only usful in conjuction with specifying --dump_action_graph
.
--dump_targets=(inputs|rules|all|packages)
If this option is specified, Bazel will dump the targets touched
by the current build request to the file BazelTargets.txt
.
--dump_targets=inputs
will dump the labels of the input
file targets.--dump_targets=rules
will dump the labels of the rule
targets.--dump_targets=all
will dump the labels of the rule
and input file targets.--dump_targets=packages
will dump the package names of
the rule and input file targets.
--dump_to_stdout
If this option is specified, the options
--dump_action_graph
, --dump_makefile
and --dump_targets
will not dump to the files
specified above but to stdout.
--explain logfile
This option, which requires a filename argument, causes the
dependency checker in bazel build
's execution phase to
explain, for each build step, either why it is being executed, or
that it is up-to-date. The explanation is written
to logfile.
If you are encountering unexpected rebuilds, this option can help to
understand the reason. Add it to your .bazelrc
so that
logging occurs for all subsequent builds, and then inspect the log
when you see an execution step executed unexpectedly. This option
may carry a small performance penalty, so you might want to remove
it when it is no longer needed.
--verbose_explanations
This option increases the verbosity of the explanations generated when the --explain option is enabled.
In particular, if verbose explanations are enabled, and an output file is rebuilt because the command used to build it has changed, then the output in the explanation file will include the full details of the new command (at least for most commands).
Using this option may significantly increase the length of the
generated explanation file and the performance penalty of using
--explain
.
If --explain
is not enabled, then
--verbose_explanations
has no effect.
--profile file
This option, which takes a filename argument, causes Bazel to write
profiling data into a file. The data then can be analyzed or parsed using the
bazel analyze-profile
command. The Build profile can be useful in
understanding where Bazel's build
command is spending its time.
--[no]show_package_location
This option causes Bazel to display, as each package is loaded, the
directory on the package path beneath
which the package's BUILD file was found. This can be useful as a
diagnostic aid. Nothing is printed if the directory was the Bazel
workspace (%workspace%
). For example:
INFO Loading package: foo/bar/scripts INFO Loading package: foo/bar/main INFO Loading package: baz from ../$WORKSPACE_READONLY_ROOT
--[no]show_loading_progress
This option causes Bazel to output package-loading progress messages. If it is disabled, the messages won't be shown.
--[no]show_progress
This option causes progress messages to be displayed; it is on by default. When disabled, progress messages are suppressed.
--show_progress_rate_limit n
This option causes Bazel to display only
one progress message per n
seconds. If n
is -1,
all progress messages will be displayed. The default value for this
option is -1.
--show_result n
This option controls the printing of result information at the end
of a bazel build
command. By default, if a single
build target was specified, Bazel prints a message stating whether
or not the target was successfully brought up-to-date, and if so,
the list of output files that the target created. If multiple
targets were specified, result information is not displayed.
While the result information may be useful for builds of a single
target or a few targets, for large builds (e.g. an entire top-level
project tree), this information can be overwhelming and distracting;
this option allows it to be controlled. --show_result
takes an integer argument, which is the maximum number of targets
for which full result information should be printed. By default,
the value is 1. Above this threshold, no result information is
shown for individual targets. Thus zero causes the result
information to be suppressed always, and a very large value causes
the result to be printed always.
Users may wish to choose a value in-between if they regularly
alternate between building a small group of targets (for example,
during the compile-edit-test cycle) and a large group of targets
(for example, when establishing a new workspace or running
regression tests). In the former case, the result information is
very useful whereas in the latter case it is less so. As with all
options, this can be specified implicitly via
the .bazelrc
file.
The files are printed so as to make it easy to copy and paste the filename to the shell, to run built executables. The "up-to-date" or "failed" messages for each target can be easily parsed by scripts which drive a build.
--show_builder_stats
This option will enable parallel builder to output several internal statistics after each completed action. Statistic includes following sections:
time since the start of execution phase; queue: cumulative number of queued and dequeued actions. At the end of the build those two numbers should be equal to the number of actions. threads: number of scheduled tasks, number of active threads in the pool, number of threads not waiting on resources and number of threads executing action payload; actions: number of actions waiting on single remaining unbuilt dependency before they can get scheduled and number of total actions in the build; locked: number of threads being blocked by resource (ram, cpu, etc) locks. >>> [action name]: for actions that are potentially on the critical build path (at the time of action completion there were no actions awaiting execution).
Examples:
____13.5 s, queue: 400 / 262, threads: 138 / 20 / 19 / 18, actions: 47 (608), locked: 1 ____22.8 s, queue: 464 / 453, threads: 11 / 11 / 3 / 3, actions: 16 (608), locked: 8 >>> action 'Building foo/bar/Myapp_deploy.jar'
Please, note, that this flag is mostly intended for internal Bazel profiling and can change or disappear at any time.
--subcommands
(-s)This option causes Bazel's execution phase to print the full command line for each command prior to executing it.
Where possible, commands are printed in a Bourne shell compatible syntax,
so that they can be easily copied and pasted to a shell command prompt.
(The surrounding parentheses are provided to protect your shell from the
cd
and exec
calls; be sure to copy them!)
All commands output by --subcommands
are executable by /bin/sh
or bash
.
See also --verbose_failures, below.
--verbose_failures
This option causes Bazel's execution phase to print the full command line for commands that failed. This can be invaluable for debugging a failing build.
Failing commands are printed in a Bourne shell compatible syntax, suitable for copying and pasting to a shell prompt.
--symlink_prefix string
Changes the prefix of the generated convenience symlinks. The
default value for the symlink prefix is bazel-
which
will create the symlinks bazel-bin
, bazel-testlogs
, and
bazel-genfiles
.
If the symbolic links cannot be created for any reason, a warning is issued but the build is still considered a success. In particular, this allows you to build in another user's client, or a read-only directory. Any paths printed in informational messages at the conclusion of a build will only use the symlink-relative short form if the symlinks point to the expected location; in other words, you can rely on the correctness of those paths, even if you cannot rely on the symlinks being created.
Some common values of this option:
Suppress symlink creation:
--symlink_prefix=/
will cause Bazel to not
create or update any symlinks. Use this option to suppress symlink
creation entirely.
Reduce clutter:
--symlink_prefix=.bazel/
will cause Bazel to create
symlinks called bin
(etc) inside a hidden
directory .bazel
. Some users use this to avoid
cluttering their bazel directory with files.
To build and run tests with Bazel, type bazel test
followed by
the name of the test targets using embedded test runner.
By default, this command performs simultaneous build and test
activity, building all specified targets (including any non-test
targets specified on the command line) and testing
*_test
and test_suite
targets as soon as
their prerequisites are built, meaning that test execution is
interleaved with building. Doing so usually results in significant
speed gains, especially when using a distributed environment.
bazel test
--cache_test_results=(yes|no|auto)
(-t)If this option is set to yes then Bazel will only rerun a test if any of the following conditions apply:
external
--test_result_expiration
option.
If 'auto' (the default), the caching behavior will be the same as 'yes' except that
Bazel will never cache test failures and never cache multiple test runs
that were requested with --runs_per_test
.
If 'no', all tests will be always executed unconditionally.
Note that test results are always saved in Bazel's output tree,
regardless of whether this option is enabled, so
you needn't have used --cache_test_results
on the
prior run(s) of bazel test
in order to get cache hits.
The option only affects whether Bazel will use previously
saved results, not whether it will save results of the current run.
Users who have enabled this option by default in
their .bazelrc
file may find the
abbreviations -t
(on) or -t-
(off)
convenient for overriding the default on a particular run.
--test_result_expiration=<seconds>
Specifies interval (in seconds) during which test results from the previous test
execution will be considered valid. This option is applicable only when used with
'yes' or default ('auto') value of the --cache_test_results
option. Otherwise,
it is ignored. Setting option to 0 expires cached results immediately and, as such, is
the same as --nocache_test_results
. Setting the option to -1 results in
never expiring the cached result.
--check_tests_up_to_date
This option tells Bazel not to run the tests, but to merely check and report the cached test results. If there are any tests which have not been previously built and run, or whose tests results are out-of-date (e.g. because the source code or the build options have changed), then Bazel will report an error message ("test result is not up-to-date"), will record the test's status as "NO STATUS" (in red, if color output is enabled), and will return a non-zero exit code.
This option also implies
--check_up_to_date
behavior.
This option may be useful for pre-submit checks.
--test_verbose_timeout_warnings
This option tells Bazel to explicitly warn the user if a test's timeout is significantly longer then the test's actual execution time. While a test's timeout should be set such that it is not flaky, a test that has a highly over-generous timeout can hide real problems that crop up unexpectedly.
For instance, a test that normally executes in a minute or two should not have a timeout of ETERNAL or LONG as these are much, much too generous. Bazel can generate a warning if the stated timeout is much too generous based on the results of the test run. This option is useful to help users decide on a good timeout value or sanity check existing timeout values.
Note that each test shard is allotted the timeout of the entire
XX_test
target. Using this option does not affect a test's timeout
value, merely warns if Bazel thinks the timeout could be restricted further.
--[no]test_keep_going
By default, all tests are run to completion. If this flag is disabled,
however, the build is aborted on any non-passing test. Subsequent build steps
and test invocations are not run, and in-flight invocations are canceled.
Do not specify both --notest_keep_going
and
--keep_going
.
--flaky_test_attempts attempts
This option specifies the maximum number of times a test should be attempted
if it fails for any reason. A test that initially fails but eventually
succeeds is reported as FLAKY
on the test summary. It is,
however, considered to be passed when it comes to identifying Bazel exit code
or total number of passed tests. Tests that fail all allowed attempts are
considered to be failed.
By default (when this option is not specified, or when it is set to
"default"), only a single attempt is allowed for regular tests, and
3 for test rules with the flaky
attribute set. You can specify
an integer value to override the maximum limit of test attempts. Bazel allows
a maximum of 10 test attempts in order to prevent abuse of the system.
--runs_per_test [regex@]number
This option specifies the number of times each test should be executed. All test executions are treated as separate tests (e.g. fallback functionality will apply to each of them independently).
The status of a target with failing runs depends on the value of the
--runs_per_test_detects_flakes
flag:
If a single number is specified, all tests will run that many times. Alternatively, a regular expression may be specified using the syntax regex@number. This constrains the effect of --runs_per_test to targets which match the regex (e.g. "--runs_per_test=^//pizza:.*@4" runs all tests under //pizza/ 4 times). This form of --runs_per_test may be specified more than once.
--[no]runs_per_test_detects_flakes
If this option is specified (by default it is not), Bazel will detect flaky test shards through --runs_per_test. If one or more runs for a single shard fail and one or more runs for the same shard pass, the target will be considered flaky with the flag. If unspecified, the target will report a failing status.
--test_summary output_style
Specifies how the test result summary should be displayed.
short
prints the results of each test along with the name of
the file containing the test output if the test failed. This is the default
value.
terse
like short
, but even shorter: only print
information about tests which did not pass.
detailed
prints each individual test case that failed, not
only each test. The names of test output files are omitted.
none
does not print test summary.
--test_output output_style
Specifies how test output should be displayed:
summary
shows a summary of whether each test passed or
failed. Also shows the output log file name for failed tests. The summary
will be printed at the end of the build (during the build, one would see
just simple progress messages when tests start, pass or fail).
This is the default behavior.
errors
sends combined stdout/stderr output from failed tests
only into the stdout immediately after test is completed, ensuring that
test output from simultaneous tests is not interleaved with each other.
Prints a summary at the build as per summary output above.
all
is similar to errors
but prints output for
all tests, including those which passed.
streamed
streams stdout/stderr output from each test in
real-time. This option implies
--test_sharding_strategy=disabled
.
--java_debug
This option causes the Java virtual machine of a java test to wait for a connection from a JDWP-compliant debugger (such as jdb or Eclipse) before starting the test. This option implies --test_output=streamed.
--[no]verbose_test_summary
By default this option is enabled, causing test times and other additional
information (such as test attempts) to be printed to the test summary. If
--noverbose_test_summary
is specified, test summary will
include only test name, test status and cached test indicator and will
be formatted to stay within 80 characters when possible.
--test_tmpdir path
Specifies temporary directory for tests executed locally. Each test will be
executed in a separate subdirectory inside this directory. The directory will
be cleaned at the beginning of the each bazel test
command.
By default, Bazel will place this directory under Bazel output base directory.
Note that this is a directory for running tests, not storing test results
(those are always stored under the bazel-out
directory).
--test_timeout
seconds
OR
--test_timeout
seconds,seconds,seconds,seconds
Overrides the timeout value for all tests by using specified number of seconds as a new timeout value. If only one value is provided, then it will be used for all test timeout categories.
Alternatively, four comma-separated values may be provided, specifying individual timeouts for short, moderate, long and eternal tests (in that order). In either form, zero or a negative value for any of the test sizes will be substituted by the default timeout for the given timeout categories. By default, Bazel will use Test Encyclopedia timeouts for all tests by inferring the timeout limit from the test's size whether the size is implicitly or explicitly set.
Tests which explicitly state their timeout category as distinct from their size will receive the same value as if that timeout had been implicitly set by the size tag. So a test of size 'small' which declares a 'long' timeout will have the same effective timeout that a 'large' tests has with no explicit timeout.
--test_arg arg
Passes command-line options/flags/arguments to the test (not to the test runner). This
option can be used multiple times to pass several arguments, e.g.
--test_arg=--logtostderr --test_arg=--v=3
.
--test_env variable=value
OR
--test_env variable
Specifies additional variables that must be injected into the test
environment for each test. If value is not specified it will be
inherited from the shell environment used to start the bazel test
command.
The environment can be accessed from within a test by using
System.getenv("var")
(Java),
--test_sharding_strategy strategy
Specifies one of the following strategies to be used for
test sharding.
With test sharding, each shard will run as a separate process and will
execute approximately (1/N)
th of the total number of tests
methods. This can result in significant test latency improvements.
The default is explicit
.
explicit
will only use sharding if the
shard_count
BUILD attribute is present.
disabled
will never shard tests.
experimental_heuristic
(experimental) will enable sharding
on distributed tests without an explicit shard_count
attribute
which link in a supported framework. This option is considered experimental
primarily because there may be false positives: in certain pathological
circumstances, Bazel might attempt to shard a test that does not speak the
sharding protocol.
--run_under=command-prefix
This specifies a prefix that the test runner will insert in front of the test command before running it. The command-prefix is split into words using Bourne shell tokenization rules, and then the list of words is prepended to the command that will be executed.
If the first word is a fully qualified label (i.e. starts with
//
) it is built. Then the label is substituted by the
corresponding executable location that is prepended to the command
that will be executed along with the other words.
Some caveats apply:
--run_under
command (the first word in command-prefix).
stdin
is not connected, so --run_under
can't be used for interactive commands.
Examples:
--run_under=/usr/bin/valgrind --run_under=/usr/bin/strace --run_under='/usr/bin/strace -c' --run_under='/usr/bin/valgrind --quiet --num-callers=20' --run_under=//testing/valgrind:tsan --run_under='//testing/valgrind:memcheck --gen-suppressions=all -v'
As documented under Output selection options, you can filter tests by size, timeout, tag, or language. A convenience general name filter can forward particular filter args to the test runner.
bazel test
The syntax and the remaining options are exactly like bazel build.
tags
attribute keywords and other
common attributes
Bazel modifies test behavior if it finds the following keywords in the
tags
attribute of the test rule:
exclusive
keyword will force test to be run in the
"exclusive" mode, ensuring that no other tests are running at the
same time. Such tests will be executed in serial fashion after all build
activity and non-exclusive tests have been completed.
manual
keyword will force test to be ignored by all command
line wildcards (...
, :*
, :all
, etc).
It will also be ignored by the test_suite
rules that do not
mention this test explicitly. The only way
to run such test is to specify it explicitly on the command line.
external
keyword will force test to be unconditionally
executed (regardless of --cache_test_results
value).
There are also several other attributes that affect test behavior:
flaky=1
attribute are considered
to be flaky and will be automatically retried up to 3 times unless larger
--flaky_test_attempts
value has been specified.
obsolete=1
attribute will be
ignored by the test_suite
rules and by all command line
wildcards - this behavior is identical to the manual
keyword
described above.
The bazel run
command is similar to bazel build
, except
it is used to build and run a single target. Here is a typical session:
% bazel run -- java/myapp:myapp --arg1 --arg2 Welcome to Bazel INFO: Loading package: java/myapp INFO: Loading package: foo/bar INFO: Loading complete. Analyzing... INFO: Building 1 target... [0%] Building java/myapp/myapp [0%] Creating runfiles directory java/myapp/myapp.runfiles ... Target //java/myapp:myappp up-to-date: bazel-bin/java/myapp:myapp INFO: Elapsed time: 5.072s Hello there $EXEC_ROOT/java/myapp/myapp --arg1 --arg2
Note the use of the --
. This is needed so that Bazel
does not interpret --arg1
and --arg2
as
Bazel options, but rather as part of the command line for running the binary.
bazel run
--run_under=command-prefix
This has the same effect as the --run_under
option for
bazel test
(see above),
except that it applies to the command being run by bazel
run
rather than to the tests being run by bazel test
and cannot run under label.
Bazel includes a query language for asking questions about the dependency graph used during the build. The query tool is an invaluable aid to many software engineering tasks.
The query language is based on the idea of algebraic operations over graphs; it is documented in detail in Bazel Query Language, revision 2. Please refer to that document for reference, for examples, and for query-specific command-line options.
The query tool accepts several command-line
option. --output
selects the output format.
--[no]keep_going
(disabled by default) causes the query
tool to continue to make progress upon errors; this behavior may be
disabled if an incomplete result is not acceptable in case of errors.
The --[no]implicit_deps
option, enabled by default, causes
implicit dependencies
to be included in the dependency graph over which the query operates. An
implicit dependency is one that is not explicitly specified in the BUILD file
but added by Bazel.
Example: "Show the locations of the definitions (in BUILD files) of all genrules required to build all the tests in the ABC tree."
bazel query --output location 'kind(genrule, deps(kind(".*_test rule", foo/bar/pebl/...)))'
help
command
The help
command provides on-line help. By default, it
shows a summary of available commands and help topics, as shown in
the Bazel Concepts section above.
Specifying an argument displays detailed help for a particular
topic. Most topics are Bazel commands, e.g. build
or query
, but there are some additional help topics
that do not correspond to commands.
--[no]long
(-l)
By default, bazel help [topic]
prints only a
summary of the relevant options for a topic. If
the --long
option is specified, the type, default value
and full description of each option is also printed.
shutdown
command
Bazel server processes (see Client/server
implementation) may be stopped by using the shutdown
command. This command causes the Bazel server to exit as soon as it
becomes idle (i.e. after the completion of any builds or other
commands that are currently in progress).
Bazel servers stop themselves after an idle timeout, so this command
is rarely necessary; however, it can be useful in scripts when it is
known that no further builds will occur in a given workspace.
shutdown
accepts one
option, --iff_heap_size_greater_than n
, which
requires an integer argument. If specified, this makes the shutdown
conditional on the amount of memory already consumed. This is
useful for scripts that initiate a lot of builds, as any memory
leaks in the Bazel server could cause it to crash spuriously on
occasion; performing a conditional restart preempts this condition.
info
command
The info
command prints various values associated with
the Bazel server instance, or with a specific build configuration.
(These may be used by scripts that drive a build.)
The info
command also permits a single (optional)
argument, which is the name of one of the keys in the list below.
In this case, bazel info key
will print only
the value for that one key. (This is especially convenient when
scripting Bazel, as it avoids the need to pipe the result
through sed -ne /key:/s/key://p
:
release
: the release label for this Bazel
instance, or "development version" if this is not a released
binary.
workspace
the absolute path to this Baze;
workspace.
install_base
: the absolute path to the installation
directory used by this Bazel instance for the current user. Bazel
installs its internally required executables below this directory.
output_base
: the absolute path to the base output
directory used by this Bazel instance for the current user and
workspace combination. Bazel puts all of its scratch and build
output below this directory.
execution_root
: the absolute path to the execution
root directory under output_base. This directory is the root for all files
accessible to commands executed during the build, and is the working
directory for those commands. If the workspace directory is writable, a
symlink is placed there pointing to this
directory.
output_path
: the absolute path to the output
directory beneath the execution root used for all files actually
generated as a result of build commands. If the workspace directory is
writable, a symlink named bazel-out
is placed there pointing
to this directory.
server_pid
: the process ID of the Bazel server
process. command_log
: the absolute path to the command log file;
this contains the interleaved stdout and stderr streams of the most recent
Bazel command. Note that running bazel info
will overwrite the
contents of this file, since it then becomes the most recent Bazel command.
However, the location of the command log file will not change unless you
change the setting of the --output_base
or
--output_user_root
options.
server_log
: the absolute path to the Bazel server's
log file; this contains useful information for debugging Bazel.
used-heap-size
,
committed-size
,
max-heap-size
: reports various JVM heap size
parameters. Respectively: memory currently used, memory currently
guaranteed to be available to the JVM from the system, maximum
possible allocation.
gc-count
, gc-time
: The cumulative count of
garbage collections since the start of this Bazel server and the time spent
to perform them. Note that these values are not reset at the start of every
build.
package_path
: A colon-separated list of paths which would be
searched for packages by Bazel. Has the same format as the
--package_path
build command line argument.
Example: the process ID of the Bazel server.
% bazel info server_pid 1285
These data may be affected by the configuration options passed
to bazel info
, for
example --define
.
The info
command accepts all
the options that control dependency
analysis, since some of these determine the location of the
output directory of a build, the choice of compiler, etc.
bazel-bin
, bazel-testlogs
,
bazel-genfiles
: reports the absolute path to
the bazel-*
directories in which programs generated by the
build are located. This is usually, though not always, the same as
the bazel-*
symlinks created in the bazel workspace after a
successful build. However, if the workspace directory is read-only,
no bazel-*
symlinks can be created. Scripts that use
the value reported by bazel info
, instead of assuming the
existence of the symlink, will be more robust.
--show_make_env
flag is
specified, all variables in the current configuration's "Make" environment
are also displayed (e.g. JAVABASE
).
These are the variables accessed using the $(JAVABASE)
or varref("JAVABASE")
syntax inside BUILD files.
version
commandThe version command prints version details about the built Bazel binary, including the changelist at which it was built and the date. These are particularly useful in determining if you have the latest Bazel. Some of the interesting values are:
label
: the release label for this Bazel
instance, or "development version" if this is not a released
binary.
analyze-profile
command
The analyze-profile
command analyzes data previously gathered
during the build using --profile
option. It provides several
options to either perform analysis of the build execution or export data in
the specified format.
canonicalize-flags
command
The canonicalize-flags
command, which takes a list of options for
a Bazel command and returns a list of options that has the same effect. The
new list of options is canonical, i.e., two lists of options with the same
effect are canonicalized to the same new list.
The --for_command
option can be used to select between different
commands. At this time, only build
and test
are
supported. Options that the given command does not support cause an error.
Note that a small number of options cannot be reordered, because Bazel cannot ensure that the effect is identical.
The options described in this section affect the startup of the Java virtual machine used by Bazel server process, and they apply to all subsequent commands handled by that server. If there is an already running Bazel server and the startup options do not match, it will be restarted.
All of the options described in this section must be specified using the
--key=value
or --key value
syntax. Also, these options must appear before the name of the Bazel
command.
--output_base=dir
This option requires a path argument, which must specify a writable directory. Bazel will use this location to write all its output. The output base is also the key by which the client locates the Bazel server. By changing the output base, you change the server which will handle the command.
By default, the output base is derived from the user's login name,
and the name of the workspace directory (actually, its MD5 digest),
so a typical value looks
like: /usr/local/_bazel_myname/d41d8cd98f00b204e9800998ecf8427e
.
Note that the client uses the output base to find the Bazel server
instance, so if you specify a different output base in a Bazel
command, a different server will be found (or started) to handle the
request. It's possible to perform two concurrent builds in the same
bazel workspace by varying the output base:
% bazel --output_base /tmp/1 build //foo & bazel --output_base /tmp/2 build //bar
In this command, the two Bazel commands run concurrently (because of
the shell &
operator), each using a different Bazel
server instance (because of the different output bases).
In contrast, if the default output base was used in both commands,
then both requests would be sent to the same server, which would
handle them sequentially: a foo
build first, followed
by an incremental build of bar
.
We recommend you do not use NFS locations for the output base, as the higher access latency of NFS will cause noticeably slower builds. Also, this places unnecessary loads on the NFS filers.
--output_user_root=dir
By default, the output_base
value is chosen to as to
avoid conflicts between multiple users building in the same client.
In some situations, though, it is desirable to build from a client
shared between multiple users; release engineers may do this. In
those cases it may be useful to deliberately override the default so
as to ensure "conflicts" (i.e., sharing) between multiple users.
Use the --output_user_root
option to achieve this: the
output base is placed in a subdirectory of the output user root,
with a unique name based on the workspace, so the result of using an
output user root that is not a function of $USER
is
sharing. Of course, it is important to ensure (via umask and group
membership) that all the cooperating users can read/write each
others files.
If the --output_base
option is specified, it overrides
using --output_user_root
to calculate the output base.
The install base location is also calculated based on
--output_user_root
, plus the MD5 identity of the Bazel embedded
binaries.
You can also use the --output_user_root
option to choose an
alternate base location for all of Bazel's output (install base and output
base) if there is a better location in your filesystem layout.
--host_jvm_args=string
Specifies a space-separated list of startup options to be passed to the Java virtual machine in which Bazel itself runs. This can be used to set the stack size, for example:
% bazel --host_jvm_args="-Xss256K" build //base
This option can be used multiple times with individual arguments. Note that
setting this flag should rarely be needed. Default heap size values passed
to the JVM from Bazel are set aggressively in both the 32-bit and 64-bit
case (3000MB
and 10GB
, respectively).
(Please note that this does not affect any JVMs used by
subprocesses of Bazel: applications, tests, tools, etc. To pass
JVM options to executable Java programs, whether run by bazel
run
or on the command-line, you should use
the --jvm_flags
argument which
all java_binary
and java_test
programs
support. Alternatively for tests, use bazel
test --test_arg=--jvm_flags=foo ...
.)
--host_jvm_debug
This option causes the Java virtual machine to wait for a connection from a JDWP-compliant debugger (such as jdb or Eclipse) before calling the main method of Bazel itself. This is primarily intended for use by Bazel developers.
(Please note that this does not affect any JVMs used by subprocesses of Bazel: applications, tests, tools, etc.)
--batch
This switch will cause Bazel to be run in batch mode, instead of the standard client/server mode described above. Doing so provides more predictable semantics with respect to signal handling, job control, and environment variable inheritance.
Batch mode retains proper queueing semantics within the same output_base. That is, simultaneous invocations will be processed in order, without overlap. If a batch mode Bazel is run on a client with a running server, it first kills the server before processing the command.
Bazel will run slower in batch mode, compared to client/server mode. Among other things, the build file cache is memory-resident, so it is not preserved between sequential batch invocations. Therefore, using batch mode often makes more sense in cases where performance is less critical, such as continuous builds.
--max_idle_secs n
This option specifies how long, in seconds, the Bazel server process should wait after the last client request, before it exits. The default value is 10800 (3 hours).
This option may be used by scripts that invoke Bazel to ensure that
they do not leave Bazel server processes on a user's machine when they
would not be running otherwise.
For example, an automated script might wish to
invoke bazel query
to ensure that a user's pending
change does not introduce unwanted dependencies. However, if the
user has not done a recent build in that workspace, it would be
undesirable for the script to start a Bazel server just
for it to remain idle for the rest of the day.
By specifying a small value of --max_idle_secs
in the
query request, the script can ensure that if it caused a new
server to start, that server will exit promptly, but if instead
there was already a server running, that server will continue to run
until it has been idle for the usual time. Of course, the existing
server's idle timer will be reset.
--[no]block_for_lock
If enabled, Bazel will wait for other Bazel commands holding the server lock to complete before progressing. If disabled, Bazel will exit in error if it cannot immediately acquire the lock and proceed. Developers might use this to avoid long waits caused by another Bazel command in the same client.
--io_nice_level n
Sets a level from 0-7 for best-effort IO scheduling. 0 is highest priority, 7 is lowest. The anticipatory scheduler may only honor up to priority 4. Negative values are ignored.
--batch_cpu_scheduling
Use batch
CPU scheduling for Bazel. This policy is useful for
workloads that are non-interactive, but do not want to lower their nice value.
See 'man 2 sched_setscheduler'. This policy may provide for better system
interactivity at the expense of Bazel throughput.
--[no]announce_rc
Controls whether Bazel announces the options read from the bazelrc file when starting up.
--color (yes|no|auto)
This option determines whether Bazel will use colors to highlight its output on the screen.
If this option is set to yes
, color output is enabled.
If this option is set to auto
, Bazel will use color output only if
the output is being sent to a terminal and the TERM environment variable
is set to a value other than dumb
, emacs
, or xterm-mono
.
If this option is set to no
, color output is disabled,
regardless of whether the output is going to a terminal and regardless
of the setting of the TERM environment variable.
--config name
Selects additional config sections from the rc files; for the current
command
, it also pulls in the options from
command:name
if such a section exists. Note that it is currently
only possible to provide these options on the command line, not in the rc
files.
--curses (yes|no|auto)
This option determines whether Bazel will use cursor controls
in its screen output. This results in less scrolling data, and a more
compact, easy-to-read stream of output from Bazel. This works well with
--color
.
If this option is set to yes
, use of cursor controls is enabled.
If this option is set to no
, use of cursor controls is disabled.
If this option is set to auto
, use of cursor controls will be
enabled under the same conditions as for --color=auto
.
--logging n
This option controls the level of logging output produced by Bazel. The default level of logging is 3 (INFO log level); higher numbers mean more output. The most detailed output is produced at level = 6. A value of 0 turns logging off.
Note, the logging output is highly technical and not intended for consumption by Bazel users. Instead, we recommend using one of the following more user-friendly options to control the diagnostic information printed by Bazel.
bazel query
.
--verbose_failures
.
--subcommands
.
--explain
.
--profile
.
--noshow_progress
.
--show_result n
.
--show_timestamps
.
--show_package_location
.
--[no]show_timestamps
If specified, a timestamp is added to each message generated by Bazel specifying the time at which the message was displayed.
Bazel can be called from scripts in order to perform a build, run tests or query the dependency graph. Bazel has been designed to enable effective scripting, but this section lists some details to bear in mind to make your scripts more robust.
The --output_base
option controls where the Bazel process should
write the outputs of a build to, as well as various working files used
internally by Bazel, one of which is a lock that guards against
concurrent mutation of the output base by multiple Bazel processes.
Choosing the correct output base directory for your script depends
on several factors. If you need to put the build outputs in a
specific location, this will dictate the output base you need to
use. If you are making a "read only" call to Bazel
(e.g. bazel query
), the locking factors will be more important.
In particular, if you need to run multiple instances of your script
concurrently, you will need to give each one a different (or random) output
base.
If you use the default output base value, you will be contending for the same lock used by the user's interactive Bazel commands. If the user issues long-running commands such as builds, your script will have to wait for those commands to complete before it can continue.
By default, Bazel uses a long-running server process as an optimization; this
behavior can be disabled using the --batch
option. There's no hard and
fast rule about whether or not your script should use a server, but
in general, the trade-off is between performance and reliability.
The server mode makes a sequence of builds, especially incremental
builds, faster, but its behavior is more complex and prone to
failure. We recommend in most cases that you use batch mode unless
the performance advantage is critical.
If you do use the server, don't forget to call shutdown
when you're finished with it, or, specify
--max_idle_secs=5
so that idle servers shut themselves
down promptly.
Bazel attempts to differentiate failures due to the source code under consideration from external errors that prevent Bazel from executing properly. Bazel execution can result in following exit codes:
Exit Codes common to all commands:0
- Success2
- Command Line Problem, Bad or Illegal flags or command
combination, or Bad Environment Variables. Your command line must be
modified.8
- Build Interrupted but we terminated with an orderly shutdown.33
- OOM failure. You need to modify your command line.36
- Local Environmental Issue, suspected permanent.37
- Unhandled Exception / Internal Bazel Error.40-44
- Reserved for errors in Bazel's command line launcher,
bazel.cc
that are not command line
related. Typically these are related to Bazel server
being unable to launch itself.bazel build
, bazel test
.
1
- Build failed.3
- Build OK, but some tests failed or timed out.4
- Build successful but no tests were found even though
testing was requested.bazel run
:
1
- Build failed.6
- Run command failure. The executed subprocess returned a
non-zero exit code. The actual subprocess exit code is
given in stderr.bazel query
:
3
- Partial success, but the query encountered 1 or more
errors in the input BUILD file set and therefore the
results of the operation are not 100% reliable.
This is likely due to a --keep_going
option
on the command line.
7
- Analyze or Query command failure.
Future Bazel versions may add additional exit codes, replacing generic failure
exit code 1
with a different non-zero value with a particular
meaning. However, all non-zero exit values will always constitute an error.
By default, Bazel will read the .bazelrc
file from the workspace
directory or the user's home directory. Whether or not this is
desirable is a choice for your script; if your script needs to be
perfectly hermetic (e.g. when doing release builds), you should
disable reading the .bazelrc file by using the option
--bazelrc=/dev/null
. If you want to perform a build
using the user's preferred settings, the default behavior is better.
On each build, test, analyze, or coverage command, Bazel will write a readily-parseable summary log. The output is in the form of a line-based grammar, familiar to standard unix tools (grep, sed, sort, awk, etc.).
The master log contains information on the result of each target and test. You'll be able to determine, for instance, if a given target passed the loading phase, but not the analysis phase. We also provide references to test log files and test time information. You can find the master log file with the following command:
% bazel info master-log
Say you were interested in seeing the three longest-running tests in your most recent test command. Here's how you could do it:
% grep '^test ' $(bazel info master-log 2>/dev/null) | awk '{print $5,$2}' | sort -nr | head -n 3 2404 //foo:foo_test 713 //bar:bar_test 624 //baz:baz_test
Line ordering is generally unspecified (exceptions are handled on a case-by-case basis), but the file will contain the following contents:
startup_options
.bazelrc
options.
cmd_line
.bazelrc
options, but not the
startup options, command, or target patterns specified on the command line.
build_id uuid
version_num number
pattern pattern ...
bazel build foo //bar:*
,
the line would read: pattern foo //bar:*
.
command command_name
bazel_version version string
log_starting log_name log_path
start_time time
stop_time time
output_fs filesystem_type
runs_per_test runs
working_directory cwd
symlink_prefix string
--symlink_prefix
flag.
See --symlink_prefix
.
target label kind
target //foo:foo java_library rule target //bar:t1 source file target //bar:t2 generated fileIf a
test_suite
target is specified in the pattern, just one
target
line will appear for it, but no target
lines
will appear for the test targets it expands to. If the test targets build
successfully, you can use the
test_target
lines to determine target language.
test_target label kind shards
One line for each test target that Bazel will attempt to execute.
These targets have been successfully loaded, analyzed, and have not been
filtered via size,
timeout,
tag, or
language. Note that these tests may not
be executed if the execution phase is not entered, is interrupted, or fails.
These lines will appear before any status
,
test
, test_status
lines.
If a test_suite
target is specified in the pattern, a
test_target
line will appear for each test target it expands to.
make_var key value
Available make variables may be displayed with:
bazel info --show_make_env
status label result
time cached
One status line for each target
line. In the
--keep_going
case, different targets may reach
different phases (e.g. loading vs. analysis) before failing.
However, in the default case, all result values will be
identical, because the build stops as soon as the first error is
encountered. This line strictly reports build statuses; for test status
reporting, see test_status
.
result may be one of:
parsing-failed
: the target could not be parsed (due to the
architecture of Bazel, this is sometimes also emitted when the target
simply does not exist). Also see
parsing_failedtarget-filtered
: the target got filtered out by a negative
target specifier that came later in the command line.loading-failed
: the target contained
a loading phase error.analysis-failed
: the target contained
an analysis phase error.test-filtered
: the target was loaded and analyzed
successfully, but was not built or run because it did not match the
current
size,
timeout,
tag, or
language test
filter settings.not-built
: the target was loaded and analyzed successfully,
but was not built or run because Bazel did not perform the
execution phase;
e.g. if the --nobuild flag was specified.build-failed
: the target could not be built
because of an error during
the execution phase.built
: the target was built successfully.action_executed target type outcome
stdout stderr primary_input
primary_output
<none>
if the action does not belong to any target.success
or failure
depending
on whether the action succeeded or failed./dev/null
if the action did not write anything there./dev/null
if the action did not write anything there.null
if the action has no input artifacts.null
if the action has no output artifacts.
root_cause target cause
root_cause
line is added. Such a line means that the
reason why target could not be built is that there was a
problem with building one of its dependencies, cause. Note
that there can be multiple root_cause
lines for a single
target when that target has multiple faulty dependencies which do not
depend on each other. Also note that a target can be its own root cause.
Root cause lines are most meaningful in the presence of --keep_going; in
builds lacking -k, only the first failing target will report root causes
(and because actions are executed in parallel, which target fails first is
not deterministic).
bazel_crashed description
OutOfMemoryError
.
bazel_catastrophe
keep_going
is set. One example of this is unexpected IO failure
when writing to local disk, whether due to physical failure or filesystem corruption.
parsing_failed pattern “description”
output_file label path tags
executable
, which is
printed if and only if the file is the target's executable
output. Each target may have at most one executable.
test label
shard_num/total_shards result time
log_file
test_status
.
Multiple runs and flaky attempts will appear on different lines. Targets which failed to build or were filtered out due to language or tags will appear as soon as the failure or filtering occurs.
shard_num: The zero-based shard index, or zero if sharding is disabled.no_status
, passed
,
failed
, timeout
or flaky
.test label failed_to_build
(deprecated) test_status label
result
Reports the final testing status of each test target as soon as it
becomes available.
For individual shard and run results, refer to
test
. The status codes roughly
mirror the status lines output to the console. Possible status codes are:
passed
: the target passed testing.failed
: the target failed in testing.timeout
: the target timed out in testing.flaky
: the target produced flaky results in testing.incomplete
: the target began testing but never completed,
most likely due to an interrupt.failed-to-build
: the target couldn't be tested because it
failed to build.no-status
: the target was scheduled to be tested but
testing was never actually performed on it, most likely due to an interrupt
or failure while building an earlier target.
baseline_coverage label filename
build_interrupted
eof
The Bazel output is also available in a command log file which you can find with the following command:
% bazel info command_log
The command log file contains the interleaved stdout and stderr streams
of the most recent Bazel command. Note that running bazel info
will overwrite the contents of this file, since it then becomes the most
recent Bazel command. However, the location of the command log file will
not change unless you change the setting of the --output_base
or --output_user_root
options.
The Bazel output is quite easy to parse for many purposes. Two
options that may be helpful for your script are
--noshow_progress
which suppresses progress messages,
and --show_result n
, which controls whether
or not "build up-to-date" messages are printed; these messages may
be parsed to discover which targets were successfully built, and the
location of the output files they created. Be sure to specify a
very large value of n if you rely on these messages.
Note that it often makes sense to use the master log instead of parsing Bazel output directly.