Bazel in Apollo¶
Overview¶
Apollo uses Bazel as its underlying build system. Bazel
is an open-source build and test tool with a human-readable, high-level build
language suitable for medium and large projects. You may notice the WORKSPACE
file under the root directory, and many BUILD, *.BUILD, workspace.bzl
files in sub-directories (e.g. third_party). They are all Bazel files.
Bazel Settings in Apollo¶
bazelrc¶
The content of .bazelrc (Apollo’s overall Bazel configuration) under the root
directory is as follows as of this writing:
try-import %workspace%/tools/bazel.rc
try-import %workspace%/.apollo.bazelrc
tools/bazel.rc is for general settings, while .apollo.bazelrc was generated
with the config sub-command of apollo.sh:
You can run
./apollo.sh config --interactive
to configure it interactively, or
./apollo.sh config --noninteractive
should be run to configure it non-interactively.
.bazelignore¶
Besides .bazelrc, the .bazelignore file under Apollo workspace also governs
Bazel’s behavior. Similar to .gitignore, .bazelignore is used to specify
directories for Bazel to ignore. Currently, the scripts, docker, docs
directories were specified.
Bazel Distribution Files Directory¶
Within .apollo.bazelrc, two directories were specified for Bazel:
startup --output_user_root="/apollo/.cache/bazel"
common --distdir="/apollo/.cache/distdir"
The startup option --output_user_root was used to specify Bazel output
directories (Ref:
Bazel Docs: Output Directory Layout).
We specify it within Apollo root directory so that it can be mounted into Docker
container by docker/scripts/dev_start.sh together with Apollo root directory
on the host.
According to Bazel Docs: Distribution Files Directories,
Using the
--distdir=/path/to/directoryoption, you can specify additional read-only directories to look for files instead of fetching them. A file is taken from such a directory if the file name is equal to the base name of the URL and additionally the hash of the file is equal to the one specified in the download request.
Since this option is especially useful for users with not-stable-enough network
connection, Apollo enabled a specific environment variable for that:
APOLLO_BAZEL_DIST_DIR. You can configure it in cyber/setup.bash, and then
run the following command for it to take effect.
source cyber/setup.bash
./apollo.sh config --noninteractive
Bazel Build, Test and Coverage¶
Please refer to Apollo Build and Test Explained.
Apollo’s Special¶
Proto Files¶
In Apollo 6.0, we recommend that proto files for each module be placed under
some separate directory, say, modules/a/proto.
Then you can run the following command to generate C++ and Python targets for all the proto files under that directory:
scripts/proto_build_generator.py modules/a/proto/BUILD
[Breaking Change] Python Files¶
Starting from Apollo 6.0, Python libraries/binaries were also managed by Bazel.
What you do in previous Apollo releases, say,
python3 modules/tools/mapshow/mapshow.py
, now should be done in either of the following approaches:
./bazel-bin/modules/tools/mapshow/mapshow # Approach #1
bazel run modules/tools/mapshow:mapshow # Approach #2