build: Bump build image to a4bc794b2b

[phlax]

Signed-off-by: Ryan Northey ryan@synca.io

Commit Message: build: Bump build image to b51ac7a0f
Additional Description:
Risk Level:
Testing:
Docs Changes:
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Platform Specific Features:
[Optional Runtime guard:]
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[phlax]

removing pyyaml from the env has broken llvm's clang_tidy_diff script which checks for it being installed and works differently accordingly

as the script is not run from a bazel task, and has no other way of depending on yaml, the easiest is to put it back for now...

[phlax]

envoyproxy/envoy-build-tools#146

[repokitteh-read-only]

CC @envoyproxy/dependency-shepherds: Your approval is needed for changes made to (bazel/.*repos.*\.bzl)|(bazel/dependency_imports\.bzl)|(api/bazel/.*\.bzl)|(.*/requirements\.txt)|(.*\.patch).

🐱

Caused by: #18041 was synchronize by phlax.

see: more, trace.

[wrowe]

Holler when this is ready for review.

[phlax]

tracking issue added here envoyproxy/envoy-build-tools#147

[wrowe]

I think you want to do one more bump here to catch up with @yanavlasov

https://github.com/envoyproxy/envoy-build-tools/commits/main

b6bc66636f16870b8390b400c2d2bc0160c71f73

[wrowe]

We now understand why this is the correct tag, for now, and this patch is comprehensive.

However, we are still fighting the missing versions.bzl with or without @yanavlasov's last updated toolchain fix. That toolchain fix does (mostly) work on the older May 6 build container.

Starting local Bazel server and connecting to it...
ERROR: error loading package '': in C:/source/bazel/dependency_imports.bzl: in C:/build/tmp/external/envoy_build_tools/toolchains/rbe_toolchains_config.bzl: cannot load '@envoy_build_tools//toolchains:configs/windows/versions.bzl': no such file

Are we missing other related bazel bumps here to function without versions.bzl? Or did we need to regenerate the build images with the new build-tools refactoring?

[yanavlasov]

My change to use RBE generator has removed the command that created that version.bzl

If we can disable clang-cl in CI if we can commit PR #17716 I'll leave this decision up to the Windows team
If we can not we need to rollback my two changes in envoy-build-tools so we can start using new build images.

[wrowe]

My change to use RBE generator has removed the command that created that version.bzl

We should be able to proceed on the clang-cl issue, updating llvm to 12.0.1 to get around the optimizer crash.

What's more concerning, please fix the resulting chaos from dropping versions.bzl (which should cause the build images to be regenerated for re-testing) here;

https://github.com/envoyproxy/envoy-build-tools/blob/b6bc66636f16870b8390b400c2d2bc0160c71f73/toolchains/rbe_toolchains_config.bzl#L4-L5

[phlax]

closing this as it has been superseded by #18220