We welcome contributions! This page covers setting up your machine to develop Bazel and, when you've made a patch, how to submit it.
In general, we prefer contributions that fix bugs or add features (as opposed to stylistic, refactoring, or “cleanup” changes).
Please check with us on the dev list before investing a lot of time in a patch. Meet Bazel maintainers and other contributors on Slack (get an invite here).
If your change has user-visible effects, consider adding release notes. If it is an incompatible change, read the guide for rolling out breaking changes.
For now we have support for IntelliJ. We don’t have IDE support for other languages in Bazel right now.
git clone https://github.com/bazelbuild/bazel.gitOn Linux/macOS, in Bash/Terminal:
cd bazel
bazel build //src:bazel
On Windows, in the Command Prompt:
cd bazel
bazel --output_user_root=c:\tmp build //src:bazel.exe
bazel-bin/src/bazel (or bazel-bin/src/bazel.exe on Windows).To work with IntelliJ:
Preferences > Other Settings > Bazel Settings).File > Import Bazel Project...) with the following settings:
Import from workspace and choose the scripts/ij.bazelproject
file as the Project view.Preferences > Editor > Code Style > Java, click Manage, then Import)
and use it when working on Bazel’s code.To test out Bazel, you need to compile it. To compile a development version of Bazel, you need a the latest released version of Bazel, which can be compiled from source.
bazel build //src:bazel builds the Bazel binary using bazel from your PATH
and the resulting binary can be found at bazel-bin/src/bazel. This is the
recommended way of rebuilding Bazel once you have bootstrapped it.
In addition to the Bazel binary, you might want to build the various tools Bazel
uses. They are located in //src/java_tools/..., //src/objc_tools/... and
//src/tools/... and their directories contain README files describing their
respective utility.
When modifying Bazel, you want to make sure that the following still works:
bazel build //:bazel-distfile. After
unzipping it in a new empty directory, run bash compile.sh all there.
It rebuilds Bazel with ./compile.sh, Bazel with the
compile.sh Bazel and Bazel with the Bazel-built binary. It compares if the
constructed Bazel builts are identical and then runs all Bazel tests with
bazel test //src/... //third_party/ijar/.... This is what we use at Google
to ensure that we don’t break Bazel when pushing new commits, too.Start creating a debug configuration for both C++ and Java in your .bazelrc
with the following:
build:debug -c dbg
build:debug --javacopt="-g"
build:debug --copt="-g"
build:debug --strip="never"
Then you can rebuild Bazel with bazel build --config debug //src:bazel and use
your favorite debugger to start debugging.
For debugging the C++ client you can just run it from gdb or lldb as you normally would. But if you want to debug the Java code, you must attach to the server using the following:
--host_jvm_debug before the
command (e.g., bazel --host_jvm_debug build //src:bazel).jdb for instance,
run jdb -attach localhost:5005.Bazel is organized in several parts:
src/main/cpp provides the command-line interface.src/main/protobuf.src/main/java and src/test/java.
tools/build_rules. If
you want to add rules, use Starlark.com.google.devtools.build.lib.rules and in
com.google.devtools.build.lib.bazel.rules. You might want to read about
the Challenges of Writing Rules first.src/main/native.To quickly search through Bazel’s source code, use Bazel Code Search. You can navigate Bazel’s repositories, branches, and files. You can also view history, diffs, and blame information. To learn more, see the Bazel Code Search User Guide.
To get started with the Bazel CI system, see Bazel Continuous Integration. To monitor the tests and builds of your Bazel contributions, use the Bazel CI Dashboard.