[CI][Fix] cmake: fix 'str' object has no attribute 'removeprefix' by sergiitk · Pull Request #42513 · grpc/grpc

sergiitk · 2026-05-28T00:24:39Z

The str.removeprefix method was introduced in Python 3.9. Some CI environments still use older versions of Python, causing template rendering to fail. Replacing it with a slice-based approach for compatibility.

We should revert this once we upgrade grpc-ubuntu20-large Kokoro base VM image.

The issue was introduced in #42172 - but it's a CI tech debt issue. Normally we should be assuming that we run a modern python.

The `str.removeprefix` method was introduced in Python 3.9. Some CI environments still use older versions of Python, causing template rendering to fail. Replacing it with a slice-based approach for compatibility. We should revert this once we upgrade `grpc-ubuntu20-large` Kokoro base VM image.

sergiitk · 2026-05-28T00:25:08Z

/gemini review

gemini-code-assist

Code Review

This pull request replaces the use of Python's str.removeprefix in templates/CMakeLists.txt.template with a slice-based alternative to support Python versions older than 3.9. The reviewer pointed out that this fix is incomplete because removeprefix is still used elsewhere in the same template file (on line 40), which will continue to cause generation failures in CI environments running older Python versions.

gemini-code-assist · 2026-05-28T00:25:41Z

    download_archive(
      <%text>${CMAKE_CURRENT_SOURCE_DIR}</%text>/${external_proto_library.destination}
-      https://storage.googleapis.com/grpc-bazel-mirror/${download_url.removeprefix("https://")}
+      https://storage.googleapis.com/grpc-bazel-mirror/${download_url[8:] if download_url.startswith("https://") else download_url}


The fix is incomplete because removeprefix is still used on line 40 of this template:

path = path.removeprefix(lib.strip_path_prefix)

Since third_party_proto_import_path is called during template rendering (e.g., on line 49 and line 720), the generation will still fail with 'str' object has no attribute 'removeprefix' in CI environments running Python < 3.9.

Please also update line 40 to a compatible alternative, such as:

if path.startswith(lib.strip_path_prefix): path = path[len(lib.strip_path_prefix):]

I saw that, but I AFAIK unlike bazel download, we don't run that particular piece of code in environments with outdated python. But if we do, I'd be happy to fix it in a follow-up PR.

sergiitk · 2026-05-28T18:11:50Z

Without this change grpc/core/master/linux/grpc_build_abseil-cpp_at_head is failing with

Traceback (most recent call last):
  File "tools/buildgen/_mako_renderer.py", line 60, in render_template
    template.render_context(context)
  File "/usr/local/lib/python3.8/dist-packages/mako/template.py", line 451, in render_context
    runtime._render_context(self, self.callable_, context, *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 916, in _render_context
    _exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 943, in _exec_template
    callable_(context, *args, **kwargs)
  File "./templates/CMakeLists.txt.template", line 517, in render_body
    [https://storage.googleapis.com/grpc-bazel-mirror/${download_url.removeprefix(](https://www.google.com/url?q=https://storage.googleapis.com/grpc-bazel-mirror/$%7Bdownload_url.removeprefix(&sa=D)"https://")}
AttributeError: 'str' object has no attribute 'removeprefix'

Traceback (most recent call last):
  File "tools/buildgen/_mako_renderer.py", line 179, in <module>
    main(sys.argv[1:])
  File "tools/buildgen/_mako_renderer.py", line 130, in main
    render_template(
  File "tools/buildgen/_mako_renderer.py", line 60, in render_template
    template.render_context(context)
  File "/usr/local/lib/python3.8/dist-packages/mako/template.py", line 451, in render_context
    runtime._render_context(self, self.callable_, context, *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 916, in _render_context
    _exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 943, in _exec_template
    callable_(context, *args, **kwargs)
  File "__templates_CMakeLists_txt_template", line 493, in render_body
AttributeError: 'str' object has no attribute 'removeprefix'

2026-05-28 01:47:19,534 FAILED: ./CMakeLists.txt [ret=1, pid=23436, time=0.3sec]
2026-05-28 01:47:19,534 WAITING: ETA 0.0 sec; 0 queued, 1 jobs running, 21 complete, 1 failed (load 1.00)

Adhoc run grpc/core/master/linux/grpc_build_abseil-cpp_at_head to verify the fix:
https://source.cloud.google.com/results/invocations/7da888f1-583d-4edd-82ac-511bb3835f8f

sergiitk · 2026-05-28T18:13:26Z

Last adhoc failed with

Traceback (most recent call last):
  File "tools/buildgen/_mako_renderer.py", line 60, in render_template
    template.render_context(context)
  File "/usr/local/lib/python3.8/dist-packages/mako/template.py", line 451, in render_context
    runtime._render_context(self, self.callable_, context, *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 916, in _render_context
    _exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 943, in _exec_template
    callable_(context, *args, **kwargs)
  File "./templates/CMakeLists.txt.template", line 729, in render_body
    ${src} ${third_party_proto_import_path(src)}
  File "./templates/CMakeLists.txt.template", line 38, in third_party_proto_import_path
    path = path.removeprefix(lib.strip_path_prefix)
AttributeError: 'str' object has no attribute 'removeprefix'

Traceback (most recent call last):
  File "tools/buildgen/_mako_renderer.py", line 179, in <module>
    main(sys.argv[1:])
  File "tools/buildgen/_mako_renderer.py", line 130, in main
    render_template(
  File "tools/buildgen/_mako_renderer.py", line 60, in render_template
    template.render_context(context)
  File "/usr/local/lib/python3.8/dist-packages/mako/template.py", line 451, in render_context
    runtime._render_context(self, self.callable_, context, *args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 916, in _render_context
    _exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
  File "/usr/local/lib/python3.8/dist-packages/mako/runtime.py", line 943, in _exec_template
    callable_(context, *args, **kwargs)
  File "__templates_CMakeLists_txt_template", line 623, in render_body
  File "__templates_CMakeLists_txt_template", line 137, in third_party_proto_import_path
AttributeError: 'str' object has no attribute 'removeprefix'

Meaning we need to fix another removeprefix usage

sergiitk · 2026-05-28T22:30:48Z

Adhoc run: https://source.cloud.google.com/results/invocations/47547d11-037c-433f-b5a9-58fdf6e4d571

sergiitk · 2026-05-29T04:34:25Z

Adhoc failed (expected), but the build advanced past the python syntax error.

…pc#42513) The `str.removeprefix` method was introduced in Python 3.9. Some CI environments still use older versions of Python, causing template rendering to fail. Replacing it with a slice-based approach for compatibility. We should revert this once we upgrade `grpc-ubuntu20-large` Kokoro base VM image. The issue was introduced in grpc#42172 - but it's a CI tech debt issue. Normally we should be assuming that we run a modern python. Closes grpc#42513 COPYBARA_INTEGRATE_REVIEW=grpc#42513 from sergiitk:fix/ci/cmake-old-python-removeprefix eefdf17 PiperOrigin-RevId: 923156519

sergiitk requested a review from murgatroid99 May 28, 2026 00:24

sergiitk added the release notes: no Indicates if PR should not be in release notes label May 28, 2026

sergiitk self-assigned this May 28, 2026

gemini-code-assist Bot reviewed May 28, 2026

View reviewed changes

minor: use mako comment so that we don't update template output

7bea3ba

Replace str.removeprefix with a custom helper in CMakeLists template

eefdf17

murgatroid99 approved these changes May 28, 2026

View reviewed changes

copybara-service Bot closed this in 00f1021 May 29, 2026

sergiitk deleted the fix/ci/cmake-old-python-removeprefix branch May 29, 2026 04:36

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[CI][Fix] cmake: fix 'str' object has no attribute 'removeprefix'#42513

[CI][Fix] cmake: fix 'str' object has no attribute 'removeprefix'#42513
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