[tasks] add back comments to test_infra_version.yaml (#32344)

Co-authored-by: Célian Raimbault <[email protected]>

tasks/buildimages.py

@@ -46,13 +46,23 @@ def update_test_infra_definitions(ctx: Context, commit_sha: str, go_mod_only: bo
     """
     Update the test-infra-definition image version in the Gitlab CI as well as in the e2e go.mod
     """
-    if not go_mod_only:
-        update_test_infra_def(".gitlab/common/test_infra_version.yml", commit_sha[:12], is_dev_image)
-
+    print(f"Updating test-infra-definitions to {commit_sha}")
     with ctx.cd("test/new-e2e"):
         ctx.run(f"go get github.com/DataDog/test-infra-definitions@{commit_sha}")
         ctx.run("go mod tidy")
 
+    if not go_mod_only:
+        prefix_comment = """# File generated by inv buildimages.update-test-infra-definitions
+# Please do not edit this file manually
+# To update the test-infra-definitions version, run `inv buildimages.update-test-infra-definitions --commit-sha <commit_sha>` [--is-dev-image]
+"""
+        update_test_infra_def(
+            file_path=".gitlab/common/test_infra_version.yml",
+            image_tag=commit_sha[:12],
+            is_dev_image=is_dev_image,
+            prefix_comment=prefix_comment,
+        )
+
 
 @task(
     help={

tasks/libs/ciproviders/gitlab_api.py

@@ -1258,12 +1258,10 @@ def full_config_get_all_stages(full_config: dict) -> set[str]:
     return all_stages
 
 
-def update_test_infra_def(file_path, image_tag, is_dev_image=False):
+def update_test_infra_def(file_path, image_tag, is_dev_image=False, prefix_comment=""):
     """
     Updates TEST_INFRA_DEFINITIONS_BUILDIMAGES in `.gitlab/common/test_infra_version.yml` file
     """
-    import yaml
-
     test_infra_def = {}
     with open(file_path) as test_infra_version_file:
         try:
@@ -1276,6 +1274,7 @@ def update_test_infra_def(file_path, image_tag, is_dev_image=False):
         except yaml.YAMLError as e:
             raise Exit(f"Error while loading {file_path}: {e}") from e
     with open(file_path, "w") as test_infra_version_file:
+        test_infra_version_file.write(prefix_comment + ('\n\n' if prefix_comment else ''))
         # Add explicit_start=True to keep the document start marker ---
         # See "Document Start" in https://www.yaml.info/learn/document.html for more details
         yaml.dump(test_infra_def, test_infra_version_file, explicit_start=True)