Evaluate a bazel build patch in CI

[wrowe]

Title: Evaluate a bazel build patch in CI

Description:
Need a mechanism to test a new bazel feature in the GCP RBE CI pipeline without resorting to rebuilding the envoy-toolchain for the unreleased commit to bazel/master.

In evaluating the proposed patch committed to /bazelbuild/bazel bazelbuild/rules_cc#94 we find ourselves unable to use the commit id for bazelisk in the .bazelversion resource file of the PR fork, without lots of extra noise.

In some cases such patches can be tested locally. But in cases like this, we are testing within the context of RBE collecting build outputs on a component level, so local execution doesn't tell us anything useful.

Note that the test PR #16043 touches .bazelversion and a corresponding fix in rules_cc (the rules_cc fix alone was a no-op.)

# ci/windows_ci_steps.sh
disk space at beginning of build:
Filesystem       Size  Used Avail Use% Mounted on
C:/tools/msys64   20G  478M   20G   3% /
No remote cache is set, skipping setup remote cache.
2021/05/18 11:25:00 Using unreleased version at commit c7d26166be6c5c75ac691124154af73ecefd0931
$TEST_TMPDIR defined: output root default is 'c:\build\tmp' and max_idle_secs default is '15'.
Starting local Bazel server and connecting to it...
WARNING: Option 'experimental_strict_action_env' is deprecated: Use --incompatible_strict_action_env instead
WARNING: Option 'host_javabase' is deprecated
WARNING: Option 'javabase' is deprecated
DEBUG: C:/build/tmp/external/bazel_toolchains/rules/rbe_repo/version_check.bzl:59:14:
Current running Bazel is not a release version and one was not defined explicitly in rbe_autoconfig target. Falling back to '3.7.2'
DEBUG: C:/build/tmp/external/bazel_toolchains/rules/rbe_repo/version_check.bzl:59:14:
Current running Bazel is not a release version and one was not defined explicitly in rbe_autoconfig target. Falling back to '3.7.2'
DEBUG: C:/build/tmp/external/bazel_toolchains/rules/rbe_repo/version_check.bzl:59:14:
Current running Bazel is not a release version and one was not defined explicitly in rbe_autoconfig target. Falling back to '3.7.2'
DEBUG: C:/build/tmp/external/bazel_toolchains/rules/rbe_repo/version_check.bzl:59:14:
Current running Bazel is not a release version and one was not defined explicitly in rbe_autoconfig target. Falling back to '3.7.2'
DEBUG: C:/build/tmp/external/bazel_toolchains/rules/rbe_repo/version_check.bzl:59:14:
Current running Bazel is not a release version and one was not defined explicitly in rbe_autoconfig target. Falling back to '3.7.2'
DEBUG: C:/build/tmp/external/rules_foreign_cc/for_workspace/bazel_version.bzl:4:14: You're using development build of Bazel, make sure it's recent - version check is disabled.

[wrowe]

@lizan @moderation @sunjayBhatia @yanavlasov for thoughts and observations on handling offbeat versions of bazel without bazel-build-tools regeneration?

[lizan]

You can generate the build-tools and push to a fork, then point Envoy to use them?

[lizan]

Or, since you're maintainer you can have RBE access locally, ping me on Slack.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as "help wanted" or "no stalebot". Thank you for your contributions.