After this PR is merged, maintainers no longer need to update .bazelrc
file, toolchain and platform related flags for RBE builds and tests
(unless there is a breaking change in Bazel related to those flags).
Maintainers just need to update the pin of @bazel-toolchains repo
regularly in the packages/bazel/package.bzl file according to
https://releases.bazel.build/bazel-toolchains.html to include the
latest checked-in toolchain configs. If rbe_autoconfig() cannot find
appropriate toolchain configs for the version of Bazel in the version of
@bazel_toolchains repo that is currently used by this project, it will pull
down the container and generate the configs on the fly as the beginning
of the build/test.
PR Close#29336
Xin Gao
Alex Eagle
Greg Magolan
Alex Eagle