site/docs/install-compile-source.md - bazel - Git at Google


            
            ---

            
            layout: documentation

            
            title: Compiling Bazel from source

            
            category: getting-started

            
            ---


            <h1 id="compiling-from-source">Compiling Bazel from Source</h1>


            This page describes how to install Bazel from source and provides

            
            troubleshooting tips for common issues.


            To build Bazel from source, you can do one of the following:


            *   Build it [using an existing Bazel binary](#build-bazel-using-bazel)


            *   Build it [without an existing Bazel binary](#bootstrap-bazel) which is known

            
                as _bootstrapping_.


            <h2 id="build-bazel-using-bazel">Build Bazel using Bazel</h2>


            <h3 id="summary">Summary</h3>


            1.  Get the latest Bazel release from the

            
                [GitHub release page](https://github.com/bazelbuild/bazel/releases) or with

            
                [Bazelisk](https://github.com/bazelbuild/bazelisk).


            2.  [Download Bazel's sources from GitHub](https://github.com/bazelbuild/bazel/archive/master.zip)

            
                and extract somewhere.

            
                Alternatively you can git clone the source tree from https://github.com/bazelbuild/bazel


            3.  Install the same prerequisites as for bootstrapping (see

            
                [for Unix-like systems](#bootstrap-unix-prereq) or

            
                [for Windows](#bootstrap-windows-prereq))


            4.  Build a development build of Bazel using Bazel:

            
                `bazel build //src:bazel-dev` (or `bazel build //src:bazel-dev.exe` on

            
                Windows)


            5.  The resulting binary is at `bazel-bin/src/bazel-dev`

            
                (or `bazel-bin\src\bazel-dev.exe` on Windows). You can copy it wherever you

            
                like and use immediately without further installation.


            Detailed instructions follow below.


            <h3 id="build-bazel-install-bazel">Step 1: Get the latest Bazel release</h3>


            **Goal**: Install or download a release version of Bazel. Make sure you can run

            
            it by typing `bazel` in a terminal.


            **Reason**: To build Bazel from a GitHub source tree, you need a pre-existing

            
            Bazel binary. You can install one from a package manager or download one from

            
            GitHub. See <a href="install.html">Installing Bazel</a>. (Or you can [build from

            
            scratch (bootstrap)](#bootstrap-bazel).)


            **Troubleshooting**:


            *   If you cannot run Bazel by typing `bazel` in a terminal:


                *   Maybe your Bazel binary's directory is not on the PATH.


                    This is not a big problem. Instead of typing `bazel`, you will need to

            
                    type the full path.


                *   Maybe the Bazel binary itself is not called `bazel` (on Unixes) or

            
                    `bazel.exe` (on Windows).


                    This is not a big problem. You can either rename the binary, or type the

            
                    binary's name instead of `bazel`.


                *   Maybe the binary is not executable (on Unixes).


                    You must make the binary executable by running `chmod +x /path/to/bazel`.


            <h3 id="build-bazel-git">Step 2: Download Bazel's sources from GitHub</h3>


            If you are familiar with Git, then just git clone https://github.com/bazelbuild/bazel


            Otherwise:


            1.  Download the

            
                [latest sources as a zip file](https://github.com/bazelbuild/bazel/archive/master.zip).


            2.  Extract the contents somewhere.


                For example create a `bazel-src` directory under your home directory and

            
                extract there.


            <h3 id="build-bazel-prerequisites">Step 3: Install prerequisites</h3>


            Install the same prerequisites as for bootstrapping (see below) -- JDK, C++

            
            compiler, MSYS2 (if you are building on Windows), etc.


            <h3 id="build-bazel-on-unixes">Step 4: Build Bazel</h3>


            <h4 id="build-bazel-on-unixes">Ubuntu Linux, macOS, and other Unix-like systems</h4>


            ([Scroll down](#build-bazel-on-windows) for instructions for Windows.)


            **Goal**: Run Bazel to build a custom Bazel binary (`bazel-bin/src/bazel-dev`).


            **Instructions**:


            1.  Start a Bash terminal


            2.  `cd` into the directory where you extracted (or cloned) Bazel's sources.


                For example if you extracted the sources under your home directory, run:


                    cd ~/bazel-src


            3.  Build Bazel from source:


                    bazel build //src:bazel-dev


                Alternatively you can run `bazel build //src:bazel --compilation_mode=opt`

            
                to yield a smaller binary but it's slower to build.


            4.  The output will be at `bazel-bin/src/bazel-dev` (or `bazel-bin/src/bazel`).


            <h4 id="build-bazel-on-windows">Windows</h4>


            ([Scroll up](#build-bazel-on-unixes) for instructions for Linux, macOS, and other

            
            Unix-like systems.)


            **Goal**: Run Bazel to build a custom Bazel binary

            
            (`bazel-bin\src\bazel-dev.exe`).


            **Instructions**:


            1.  Start Command Prompt (Start Menu &gt; Run &gt; "cmd.exe")


            2.  `cd` into the directory where you extracted (or cloned) Bazel's sources.


                For example if you extracted the sources under your home directory, run:


                    cd %USERPROFILE%\bazel-src


            3.  Build Bazel from source:


                    bazel build //src:bazel-dev.exe


                Alternatively you can run `bazel build //src:bazel.exe

            
                --compilation_mode=opt` to yield a smaller binary but it's slower to build.


            4.  The output will be at `bazel-bin\src\bazel-dev.exe` (or

            
                `bazel-bin\src\bazel.exe`).


            <h3 id="build-bazel-install">Step 5: Install the built binary</h3>


            Actually, there's nothing to install.


            The output of the previous step is a self-contained Bazel binary. You can copy

            
            it to any directory and use immediately. (It's useful if that directory is on

            
            your PATH so that you can run "bazel" everywhere.)


            ---


            <h2 id="bootstrap-bazel">Build Bazel from scratch (bootstrapping)</h2>


            You can also build Bazel from scratch, without using an existing Bazel binary.


            <h3 id="download-distfile">Step 1: Download Bazel's sources (distribution archive)</h3>


            (This step is the same for all platforms.)


            1.  Download `bazel-<version>-dist.zip` from

            
                [GitHub](https://github.com/bazelbuild/bazel/releases), for example

            
                `bazel-0.28.1-dist.zip`.


                **Attention**:


                -   There is a **single, architecture-independent** distribution archive.

            
                    There are no architecture-specific or OS-specific distribution archives.

            
                -   These sources are **not the same as the GitHub source tree**. You

            
                    have to use the distribution archive to bootstrap Bazel. You cannot

            
                    use a source tree cloned from GitHub. (The distribution archive contains

            
                    generated source files that are required for bootstrapping and are not part

            
                    of the normal Git source tree.)


            2.  Unpack the distribution archive somewhere on disk.


                You should verify the signature made by Bazel's

            
                [release key](https://bazel.build/bazel-release.pub.gpg) 3D5919B448457EE0.


            <h3 id="bootstrap-unix">Step 2a: Bootstrap Bazel on Ubuntu Linux, macOS, and other Unix-like systems</h3>


            ([Scroll down](#bootstrap-windows) for instructions for Windows.)


            <h4 id="bootstrap-unix-prereq">2.1. Install the prerequisites</h4>


            *   **Bash**


            *   **zip, unzip**


            *   **C++ build toolchain**


            *   **JDK.** Versions 8 and 11 are supported.


            *   **Python**. Versions 2 and 3 are supported, installing one of them is

            
                enough.


            For example on Ubuntu Linux you can install these requirements using the

            
            following command:


            ```sh

            
            sudo apt-get install build-essential openjdk-11-jdk python zip unzip

            
            ```


            <h4 id="bootstrap-unix-bootstrap">2.2. Bootstrap Bazel</h4>


            1.  Open a shell or Terminal window.


            3.  `cd` to the directory where you unpacked the distribution archive.


            3.  Run the compilation script: `env EXTRA_BAZEL_ARGS="--host_javabase=@local_jdk//:jdk" bash ./compile.sh`.


            The compiled output is placed into `output/bazel`. This is a self-contained

            
            Bazel binary, without an embedded JDK. You can copy it anywhere or use it

            
            in-place. For convenience, copy this binary to a directory that's on your

            
            `PATH` (such as `/usr/local/bin` on Linux).


            To build the `bazel` binary in a reproducible way, also set

            
            [`SOURCE_DATE_EPOCH`](https://reproducible-builds.org/specs/source-date-epoch/)

            
            in the "Run the compilation script" step.


            <h3 id="bootstrap-windows">Step 2b: Bootstrap Bazel on Windows</h3>


            ([Scroll up](#bootstrap-unix) for instructions for Linux, macOS, and other

            
            Unix-like systems.)


            <h4 id="bootstrap-windows-prereq">2.1. Install the prerequisites</h4>


            *   [MSYS2 shell](https://msys2.github.io/)


            *   **The MSYS2 packages for zip and unzip.** Run the following command in the MSYS2 shell:


                ```

            
                pacman -S zip unzip patch

            
                ```


            *   **The Visual C++ compiler.** Install the Visual C++ compiler either as part

            
                of Visual Studio 2015 or newer, or by installing the latest [Build Tools

            
                for Visual Studio 2017](https://aka.ms/BuildTools).


            *   **JDK 8.** You must install version 8 of the JDK. Versions other than 8 are

            
                *not* supported.


            *   **Python**. Versions 2 and 3 are supported, installing one of them is

            
                enough. You need the Windows-native version (downloadable from

            
                [https://www.python.org](https://www.python.org)).  Versions installed via

            
                pacman in MSYS2 will not work.


            <h4 id="bootstrap-windows-bootstrap">2.2. Bootstrap Bazel</h4>


            1.  Open the MSYS2 shell.


            2.  Set the following environment variables:

            
                *   Either `BAZEL_VS` or `BAZEL_VC` (they are *not* the same): Set to the

            
                    path to the Visual Studio directory (BAZEL\_V<b>S</b>) or to the Visual

            
                    C++ directory (BAZEL\_V<b>C</b>). Setting one of them is enough.

            
                *   `BAZEL_SH`: Path of the MSYS2 `bash.exe`. See the command in the

            
                    examples below.


                    Do not set this to `C:\Windows\System32\bash.exe`. (You have that file

            
                    if you installed Windows Subsystem for Linux.) Bazel does not support

            
                    this version of `bash.exe`.

            
                *   `PATH`: Add the Python directory.

            
                *   `JAVA_HOME`: Set to the JDK directory.


                **Example** (using BAZEL\_V<b>S</b>):


                    export BAZEL_VS="C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools"

            
                    export BAZEL_SH="$(cygpath -m $(realpath $(which bash)))"

            
                    export PATH="/c/python27:$PATH"

            
                    export JAVA_HOME="C:/Program Files/Java/jdk1.8.0_112"


                or (using BAZEL\_V<b>C</b>):


                    export BAZEL_VC="C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC"

            
                    export BAZEL_SH="$(cygpath -m $(realpath $(which bash)))"

            
                    export PATH="/c/python27:$PATH"

            
                    export JAVA_HOME="C:/Program Files/Java/jdk1.8.0_112"


            3.  `cd` to the directory where you unpacked the distribution archive.


            4.  Run the compilation script: `env EXTRA_BAZEL_ARGS="--host_javabase=@local_jdk//:jdk" ./compile.sh`


            The compiled output is placed into `output/bazel.exe`. This is a self-contained

            
            Bazel binary, without an embedded JDK. You can copy it anywhere or use it

            
            in-place. For convenience, copy this binary to a directory that's on

            
            your `PATH`.


            To build the `bazel.exe` binary in a reproducible way, also set

            
            [`SOURCE_DATE_EPOCH`](https://reproducible-builds.org/specs/source-date-epoch/)

            
            in the "Run the compilation script" step.


            You don't need to run Bazel from the MSYS2 shell. You can run Bazel from the

            
            Command Prompt (`cmd.exe`) or PowerShell.
	---
	layout: documentation
	title: Compiling Bazel from source
	category: getting-started
	---

	<h1 id="compiling-from-source">Compiling Bazel from Source</h1>

	This page describes how to install Bazel from source and provides
	troubleshooting tips for common issues.

	To build Bazel from source, you can do one of the following:

	* Build it [using an existing Bazel binary](#build-bazel-using-bazel)

	* Build it [without an existing Bazel binary](#bootstrap-bazel) which is known
	as _bootstrapping_.

	<h2 id="build-bazel-using-bazel">Build Bazel using Bazel</h2>

	<h3 id="summary">Summary</h3>

	1. Get the latest Bazel release from the
	[GitHub release page](https://github.com/bazelbuild/bazel/releases) or with
	[Bazelisk](https://github.com/bazelbuild/bazelisk).

	2. [Download Bazel's sources from GitHub](https://github.com/bazelbuild/bazel/archive/master.zip)
	and extract somewhere.
	Alternatively you can git clone the source tree from https://github.com/bazelbuild/bazel

	3. Install the same prerequisites as for bootstrapping (see
	[for Unix-like systems](#bootstrap-unix-prereq) or
	[for Windows](#bootstrap-windows-prereq))

	4. Build a development build of Bazel using Bazel:
	`bazel build //src:bazel-dev` (or `bazel build //src:bazel-dev.exe` on
	Windows)

	5. The resulting binary is at `bazel-bin/src/bazel-dev`
	(or `bazel-bin\src\bazel-dev.exe` on Windows). You can copy it wherever you
	like and use immediately without further installation.

	Detailed instructions follow below.

	<h3 id="build-bazel-install-bazel">Step 1: Get the latest Bazel release</h3>

	Goal: Install or download a release version of Bazel. Make sure you can run
	it by typing `bazel` in a terminal.

	Reason: To build Bazel from a GitHub source tree, you need a pre-existing
	Bazel binary. You can install one from a package manager or download one from
	GitHub. See <a href="install.html">Installing Bazel</a>. (Or you can [build from
	scratch (bootstrap)](#bootstrap-bazel).)

	Troubleshooting:

	* If you cannot run Bazel by typing `bazel` in a terminal:

	* Maybe your Bazel binary's directory is not on the PATH.

	This is not a big problem. Instead of typing `bazel`, you will need to
	type the full path.

	* Maybe the Bazel binary itself is not called `bazel` (on Unixes) or
	`bazel.exe` (on Windows).

	This is not a big problem. You can either rename the binary, or type the
	binary's name instead of `bazel`.

	* Maybe the binary is not executable (on Unixes).

	You must make the binary executable by running `chmod +x /path/to/bazel`.

	<h3 id="build-bazel-git">Step 2: Download Bazel's sources from GitHub</h3>

	If you are familiar with Git, then just git clone https://github.com/bazelbuild/bazel

	Otherwise:

	1. Download the
	[latest sources as a zip file](https://github.com/bazelbuild/bazel/archive/master.zip).

	2. Extract the contents somewhere.

	For example create a `bazel-src` directory under your home directory and
	extract there.

	<h3 id="build-bazel-prerequisites">Step 3: Install prerequisites</h3>

	Install the same prerequisites as for bootstrapping (see below) -- JDK, C++
	compiler, MSYS2 (if you are building on Windows), etc.

	<h3 id="build-bazel-on-unixes">Step 4: Build Bazel</h3>

	<h4 id="build-bazel-on-unixes">Ubuntu Linux, macOS, and other Unix-like systems</h4>

	([Scroll down](#build-bazel-on-windows) for instructions for Windows.)

	Goal: Run Bazel to build a custom Bazel binary (`bazel-bin/src/bazel-dev`).

	Instructions:

	1. Start a Bash terminal

	2. `cd` into the directory where you extracted (or cloned) Bazel's sources.

	For example if you extracted the sources under your home directory, run:

	cd ~/bazel-src

	3. Build Bazel from source:

	bazel build //src:bazel-dev

	Alternatively you can run `bazel build //src:bazel --compilation_mode=opt`
	to yield a smaller binary but it's slower to build.

	4. The output will be at `bazel-bin/src/bazel-dev` (or `bazel-bin/src/bazel`).

	<h4 id="build-bazel-on-windows">Windows</h4>

	([Scroll up](#build-bazel-on-unixes) for instructions for Linux, macOS, and other
	Unix-like systems.)

	Goal: Run Bazel to build a custom Bazel binary
	(`bazel-bin\src\bazel-dev.exe`).

	Instructions:

	1. Start Command Prompt (Start Menu > Run > "cmd.exe")

	2. `cd` into the directory where you extracted (or cloned) Bazel's sources.

	For example if you extracted the sources under your home directory, run:

	cd %USERPROFILE%\bazel-src

	3. Build Bazel from source:

	bazel build //src:bazel-dev.exe

	Alternatively you can run `bazel build //src:bazel.exe
	--compilation_mode=opt` to yield a smaller binary but it's slower to build.

	4. The output will be at `bazel-bin\src\bazel-dev.exe` (or
	`bazel-bin\src\bazel.exe`).

	<h3 id="build-bazel-install">Step 5: Install the built binary</h3>

	Actually, there's nothing to install.

	The output of the previous step is a self-contained Bazel binary. You can copy
	it to any directory and use immediately. (It's useful if that directory is on
	your PATH so that you can run "bazel" everywhere.)

	---

	<h2 id="bootstrap-bazel">Build Bazel from scratch (bootstrapping)</h2>

	You can also build Bazel from scratch, without using an existing Bazel binary.

	<h3 id="download-distfile">Step 1: Download Bazel's sources (distribution archive)</h3>

	(This step is the same for all platforms.)

	1. Download `bazel-<version>-dist.zip` from
	[GitHub](https://github.com/bazelbuild/bazel/releases), for example
	`bazel-0.28.1-dist.zip`.

	Attention:

	- There is a single, architecture-independent distribution archive.
	There are no architecture-specific or OS-specific distribution archives.
	- These sources are not the same as the GitHub source tree. You
	have to use the distribution archive to bootstrap Bazel. You cannot
	use a source tree cloned from GitHub. (The distribution archive contains
	generated source files that are required for bootstrapping and are not part
	of the normal Git source tree.)

	2. Unpack the distribution archive somewhere on disk.

	You should verify the signature made by Bazel's
	[release key](https://bazel.build/bazel-release.pub.gpg) 3D5919B448457EE0.

	<h3 id="bootstrap-unix">Step 2a: Bootstrap Bazel on Ubuntu Linux, macOS, and other Unix-like systems</h3>

	([Scroll down](#bootstrap-windows) for instructions for Windows.)

	<h4 id="bootstrap-unix-prereq">2.1. Install the prerequisites</h4>

	* Bash

	* zip, unzip

	* C++ build toolchain

	* JDK. Versions 8 and 11 are supported.

	* Python. Versions 2 and 3 are supported, installing one of them is
	enough.

	For example on Ubuntu Linux you can install these requirements using the
	following command:

	```sh
	sudo apt-get install build-essential openjdk-11-jdk python zip unzip
	```

	<h4 id="bootstrap-unix-bootstrap">2.2. Bootstrap Bazel</h4>

	1. Open a shell or Terminal window.

	3. `cd` to the directory where you unpacked the distribution archive.

	3. Run the compilation script: `env EXTRA_BAZEL_ARGS="--host_javabase=@local_jdk//:jdk" bash ./compile.sh`.

	The compiled output is placed into `output/bazel`. This is a self-contained
	Bazel binary, without an embedded JDK. You can copy it anywhere or use it
	in-place. For convenience, copy this binary to a directory that's on your
	`PATH` (such as `/usr/local/bin` on Linux).

	To build the `bazel` binary in a reproducible way, also set
	[`SOURCE_DATE_EPOCH`](https://reproducible-builds.org/specs/source-date-epoch/)
	in the "Run the compilation script" step.

	<h3 id="bootstrap-windows">Step 2b: Bootstrap Bazel on Windows</h3>

	([Scroll up](#bootstrap-unix) for instructions for Linux, macOS, and other
	Unix-like systems.)

	<h4 id="bootstrap-windows-prereq">2.1. Install the prerequisites</h4>

	* [MSYS2 shell](https://msys2.github.io/)

	* The MSYS2 packages for zip and unzip. Run the following command in the MSYS2 shell:

	```
	pacman -S zip unzip patch
	```

	* The Visual C++ compiler. Install the Visual C++ compiler either as part
	of Visual Studio 2015 or newer, or by installing the latest [Build Tools
	for Visual Studio 2017](https://aka.ms/BuildTools).

	* JDK 8. You must install version 8 of the JDK. Versions other than 8 are
	not supported.

	* Python. Versions 2 and 3 are supported, installing one of them is
	enough. You need the Windows-native version (downloadable from
	[https://www.python.org](https://www.python.org)). Versions installed via
	pacman in MSYS2 will not work.

	<h4 id="bootstrap-windows-bootstrap">2.2. Bootstrap Bazel</h4>

	1. Open the MSYS2 shell.

	2. Set the following environment variables:
	* Either `BAZEL_VS` or `BAZEL_VC` (they are not the same): Set to the
	path to the Visual Studio directory (BAZEL\_V<b>S</b>) or to the Visual
	C++ directory (BAZEL\_V<b>C</b>). Setting one of them is enough.
	* `BAZEL_SH`: Path of the MSYS2 `bash.exe`. See the command in the
	examples below.

	Do not set this to `C:\Windows\System32\bash.exe`. (You have that file
	if you installed Windows Subsystem for Linux.) Bazel does not support
	this version of `bash.exe`.
	* `PATH`: Add the Python directory.
	* `JAVA_HOME`: Set to the JDK directory.

	Example (using BAZEL\_V<b>S</b>):

	export BAZEL_VS="C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools"
	export BAZEL_SH="$(cygpath -m $(realpath $(which bash)))"
	export PATH="/c/python27:$PATH"
	export JAVA_HOME="C:/Program Files/Java/jdk1.8.0_112"

	or (using BAZEL\_V<b>C</b>):

	export BAZEL_VC="C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC"
	export BAZEL_SH="$(cygpath -m $(realpath $(which bash)))"
	export PATH="/c/python27:$PATH"
	export JAVA_HOME="C:/Program Files/Java/jdk1.8.0_112"

	3. `cd` to the directory where you unpacked the distribution archive.

	4. Run the compilation script: `env EXTRA_BAZEL_ARGS="--host_javabase=@local_jdk//:jdk" ./compile.sh`

	The compiled output is placed into `output/bazel.exe`. This is a self-contained
	Bazel binary, without an embedded JDK. You can copy it anywhere or use it
	in-place. For convenience, copy this binary to a directory that's on
	your `PATH`.

	To build the `bazel.exe` binary in a reproducible way, also set
	[`SOURCE_DATE_EPOCH`](https://reproducible-builds.org/specs/source-date-epoch/)
	in the "Run the compilation script" step.

	You don't need to run Bazel from the MSYS2 shell. You can run Bazel from the
	Command Prompt (`cmd.exe`) or PowerShell.