This repository provides the implementation to build ChromeOS with Bazel.
For building ChromeOS with Bazel, use the following repo
command to check out with a few additional repositories.
$ mkdir ~/chromiumos $ cd ~/chromiumos $ repo init -u https://chrome-internal.googlesource.com/chromeos/manifest-internal -g default,bazel -b main $ repo sync -c -j 4 $ cd src
Unless otherwise specified, examples in this doc assume that your current directory is ~/chromiumos/src
.
Now you're ready to start building. To build a single Portage package, e.g. sys-apps/attr:
$ BOARD=amd64-generic bazel build @portage//sys-apps/attr
To build all packages included in the ChromeOS base image:
$ BOARD=amd64-generic bazel build @portage//virtual/target-os:package_set
which bazel
prints a path under your depot_tools checkout. The wrapper script provided by depot_tools performs additional tasks besides running the real bazel
executable.Inside CrOS SDK chroot (i.e. the build environment you enter with cros_sdk
command), you should be able to run the same command except that you need to use /mnt/host/source/chromite/bin/bazel
instead of bazel
.
For example:
$ BOARD=amd64-generic /mnt/host/source/chromite/bin/bazel build @portage//sys-apps/attr
You can also run build_packages --bazel --board=$BOARD
to run build_packages
with Bazel.
We have the following targets to build images:
//bazel/images:chromiumos_minimal_image
: Minimal image that contains sys-apps/baselayout
and sys-kernel/chromeos-kernel
only.//bazel/images:chromiumos_base_image
: Base image.//bazel/images:chromiumos_dev_image
: Dev image.//bazel/images:chromiumos_test_image
: Test image.As of June 2023, we primarily test our builds for amd64-generic and arm64-generic. Please file bugs if images don't build for these two boards. Other boards may or may not work (yet).
Building a ChromeOS image takes several hours. Most packages build in a few minutes, but there are several known heavy packages, such as chromeos-base/chromeos-chrome
that takes 2-3 hours. You can inject prebuilt binary packages to bypass building those packages. See Injecting prebuilt binary packages for more details.
After building an image, you can use cros_vm
command available in CrOS SDK to run a VM locally. Make sure to copy an image out from bazel-bin
as it's not writable by default.
$ cp bazel-bin/bazel/images/chromiumos_base_image.bin /tmp/ $ chmod +w /tmp/chromiumos_base_image.bin $ chromite/bin/cros_vm --start --board=amd64-generic --image-path /tmp/chromiumos_base_image.bin
You can use VNC viewer to view the VM.
$ vncviewer localhost:5900
You can also use cros_vm
command to stop the VM.
$ chromite/bin/cros_vm --stop
The run_tests.sh
script runs currently available tests:
$ portage/tools/run_tests.sh
Optionally, you can skip running some tests by specifying some of the following environment variables when running run_tests.sh
: SKIP_CARGO_TESTS=1
, SKIP_BAZEL_TESTS=1
, SKIP_PORTAGE_TESTS=1
.
portage/
... for building Portage packages (aka Alchemy)bin/
... executablescommon/
... common Rust/Go librariesbuild_defs/
... build rule definitions in Starlarkrepo_defs/
... additional repository definitionsprebuilts/
... defines prebuilt binariessdk/
... defines the base SDKtools/
... misc small tools for developmentimages/
... defines ChromeOS image targetsworkspace_root/
... contains various files to be symlinked to the workspace root, including WORKSPACE.bazel
and BUILD.bazel
If a package is failing to build, it‘s sometimes useful to view the package’s work directory. To do this run:
bazel build --sandbox_debug //your/ebuild
In the build output you will see a cd
into the execroot
:
cd /home/rrangel/.cache/bazel/_bazel_rrangel/ca19c0757f7accdebe9bbcbd2cb0838e/sandbox/linux-sandbox/842/execroot/__main__
This directory will contain a directory called build_package.*
. It contains all the artifacts that were generated while building the package.
Build logs can be found in:
scratch/diff/build/arm64-generic/tmp/portage/logs/
The package work dir can be found in:
scratch/diff/build/<board>/tmp/portage/<category>/<package>-<version>
Sometimes you want to enter an ephemeral CrOS chroot where a package build is failing to inspect the environment interactively.
To enter an ephemeral CrOS chroot, run the following command:
$ BOARD=arm64-generic bazel run @portage//sys-apps/attr:debug -- --login=after
This command will give you an interactive shell after building a package. You can also specify other values to --login
to choose the timing to enter an interactive console:
--login=before
: before building the package--login=after
: after building the package--login=after-fail
: after failing to build the packageIn the case your work is blocked by some package build failures, you can workaround them by injecting prebuilt binary packages via command line flags.
For every ebuild
target under @portage//internal/packages/...
, an associated string flag target is defined. You can set a gs://
URL of a prebuilt binary package to inject it.
For example, to inject a prebuilt binary packages for chromeos-chrome
, you can set this option:
--@portage//internal/packages/stage1/target/board/chromiumos/chromeos-base/chromeos-chrome:114.0.5715.0_rc-r2_prebuilt=gs://chromeos-prebuilt/board/amd64-generic/postsubmit-R114-15427.0.0-49533-8783437624917045025/packages/chromeos-base/chromeos-chrome-114.0.5715.0_rc-r2.tbz2
You can run generate_chrome_prebuilt_config.py to generate the prebuilt config for the current version of chromeos-chrome.
% BOARD=amd64-generic portage/tools/generate_chrome_prebuilt_config.py
We have several named config groupings in prebuilts.bazelrc that define typical options to inject prebuilts. You can specify --config
to use them.
--config=prebuilts/arm64-generic
: Injects prebuilt binary packages needed to build arm64-generic images.In case you need to extract the contents of a binary package so you can easily inspect it, you can use the xpak split
CLI.
bazel run //bazel/portage/bin/xpak:xpak -- split --extract libffi-3.1-r8.tbz2 libusb-0-r2.tbz2
If you'd like to run the tests every time you commit, add the following. You can skip it with git commit --no-verify
.
cd ~/chromiumos/src/bazel ln -s ../../../../../src/bazel/portage/tools/run_tests.sh .git/hooks/pre-commit