Bazel is a native Windows binary.
Bazel runs on 64 bit Windows 7 or higher, and on equivalent Windows Server versions. Check Microsoft's Operating System Version table to see if your OS is supported.
We mark Windows-related Bazel issues on GitHub with the “multi-platform > windows” label. You can see the open issues here.
It's best to run Bazel from the Command Prompt (cmd.exe) or from PowerShell.
You can also run Bazel from the MSYS2 shell, but you need to disable MSYS2's automatic path conversion. See this StackOverflow answer for details.
Python 2.7 or later.
Use the Windows-native Python version. Do not use Python that comes with the MSYS2 shell or that you installed in MSYS using Pacman because it doesn't work with Bazel.
You also need to set the BAZEL_SH environment variable to point to bash.exe. For example in the Windows Command Prompt (cmd.exe):
set BAZEL_SH=C:\tools\msys64\usr\bin\bash.exe
Note: do not use quotes (") around the path like you would on Unixes. Windows doesn't need them and it may confuse Bazel.
Several MSYS2 packages.
Run the following command in the MSYS2 shell to install them:
pacman -Syuu git curl zip unzip
Java JDK 8.
JDK 7 and 9 are not supported.
This step is not required if you downloaded a binary distribution of Bazel because it has JDK 8 embedded.
If you built Bazel from source: set the JAVA_HOME environment variable to the JDK's directory.
For example in the Windows Command Prompt (cmd.exe):
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_112
Note: do not use quotes (") around the path like you would on Unix. Windows doesn't need them and they may confuse Bazel.
This step is not required if you downloaded a binary distribution of Bazel or installed Bazel using Chocolatey. See installing Bazel on Windows.
Microsoft Visual C++ Redistributable for Visual Studio 2015
This may already be installed on your system.
Environment variables you set in the Windows Command Prompt (cmd.exe) are only set in that command prompt session. If you start a new cmd.exe, you need to set the variables again. To always set the variables when cmd.exe starts, you can add them to the User variables or System variables in the Control Panel > System Properties > Advanced > Environment Variables... dialog box.
See Install Bazel on Windows for installation instructions.
The first time you build any target, Bazel auto-configures the location of Python and the Visual C++ compiler. If you need to auto-configure again, run bazel clean then build a target.
You can also tell Bazel where to find the Python binary and the C++ compiler:
--python_path=c:\path\to\python.exe flag for PythonBAZEL_VC or BAZEL_VS environment variable. See the Build C++ section below.To build C++ targets, you need:
The Visual C++ compiler.
You can install it in one of the following ways:
Install Visual Studio 2015 or later (Community Edition is enough) with Visual C++.
Make sure to also install the Visual C++ > Common Tools for Visual C++ and Visual C++ > Microsoft Foundation Classes for C++ features. These features are not installed by default.
Install the Visual C++ Build Tools 2015 or later.
Due to a known issue with Bazel's support for the Build Tools for Visual Studio 2017, we currently recommend using the 2015 version instead.
The BAZEL_VS or BAZEL_VC environment variable.
Bazel tries to locate the C++ compiler the first time you build any target. To tell Bazel where the compiler is, you can set one of the following environment variables:
BAZEL_VS storing the Visual Studio installation directory
BAZEL_VC storing the Visual C++ Build Tools installation directory
Setting one of these variables is enough. For example:
set BAZEL_VS=C:\Program Files (x86)\Microsoft Visual Studio 14.0
or
set BAZEL_VC=C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC
The Windows SDK.
The Windows SDK contains header files and libraries you need when building Windows applications, including Bazel itself.
If everything is set up, you can build a C++ target now!
Try building a target from one of our sample projects:
C:\projects\bazel> bazel build //examples/cpp:hello-world C:\projects\bazel> bazel-bin\examples\cpp\hello-world.exe
There's no setup necessary.
On Windows, Bazel builds two output files for java_binary rules:
.jar file.exe file that can set up the environment for the JVM and run the binaryTry building a target from one of our sample projects:
C:\projects\bazel> bazel build //examples/java-native/src/main/java/com/example/myproject:hello-world C:\projects\bazel> bazel-bin\examples\java-native\src\main\java\com\example\myproject\hello-world.exe
To build Python targets, you need:
Both Python 2 and Python 3 are supported.
To tell Bazel where Python is, you can use --python_path=<path/to/python>. For example:
bazel build --python_path=C:/Python27/python.exe ...
If --python_path is not specified, Bazel uses python.exe as the interpreter and the binary looks for it in $PATH during runtime. If it is not in $PATH(for example, when you use py_binary as an action's executable, Bazel will sanitize $PATH), then the execution will fail.
On Windows, Bazel builds two output files for py_binary rules:
You can either run the executable file (it has a .exe extension) or you can run Python with the self-extracting zip file as the argument.
Try building a target from one of our sample projects:
C:\projects\bazel> bazel build //examples/py_native:bin C:\projects\bazel> bazel-bin\examples\py_native\bin.exe C:\projects\bazel> python bazel-bin\examples\py_native\bin.zip
If you are interested in details about how Bazel builds Python targets on Windows, check out this design doc.