chore(ci-visibility): fix git temp dir (#5992)

CI Visibility: If there is an exception while using the temporary dir to
unpack git commits, use cwd instead.

This is an issue that happens on certain CI environments, not just for
Python.

## Checklist
- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines)
are followed.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.

Author: gnufede

ddtrace/ext/git.py

@@ -227,8 +227,28 @@ def extract_user_git_metadata(env=None):
 def build_git_packfiles(revisions, cwd=None):
     # type: (str, Optional[str]) -> Generator
     basename = str(random.randint(1, 1000000))
-    with TemporaryDirectory() as tempdir:
-        prefix = "{tempdir}/{basename}".format(tempdir=tempdir, basename=basename)
+    try:
+        with TemporaryDirectory() as tempdir:
+            prefix = "{tempdir}/{basename}".format(tempdir=tempdir, basename=basename)
+            _git_subprocess_cmd(
+                "pack-objects --compression=9 --max-pack-size=3m %s" % prefix, cwd=cwd, std_in=revisions.encode("utf-8")
+            )
+            yield prefix
+    except ValueError:
+        # The generation of pack files in the temporary folder (`TemporaryDirectory()`)
+        # sometimes fails in certain CI setups with the error message
+        # `unable to rename temporary pack file: Invalid cross-device link`.
+        # The reason why is unclear.
+        #
+        # A workaround is to attempt to generate the pack files in `cwd`.
+        # While this works most of the times, it's not ideal since it affects the git status.
+        # This workaround is intended to be temporary.
+        #
+        # TODO: fix issue and remove workaround.
+        if not cwd:
+            cwd = os.getcwd()
+
+        prefix = "{tempdir}/{basename}".format(tempdir=cwd, basename=basename)
         _git_subprocess_cmd(
             "pack-objects --compression=9 --max-pack-size=3m %s" % prefix, cwd=cwd, std_in=revisions.encode("utf-8")
         )

tests/ci_visibility/test_ci_visibility.py

@@ -340,6 +340,31 @@ def test_git_client_build_packfiles(git_repo):
     assert not os.path.isdir(directory)
 
 
+@mock.patch("ddtrace.ext.git.TemporaryDirectory")
+def test_git_client_build_packfiles_temp_dir_value_error(_temp_dir_mock, git_repo):
+    _temp_dir_mock.side_effect = ValueError("Invalid cross-device link")
+    found_rand = found_idx = found_pack = False
+    with CIVisibilityGitClient._build_packfiles("%s\n" % TEST_SHA, cwd=git_repo) as packfiles_path:
+        assert packfiles_path
+        parts = packfiles_path.split("/")
+        directory = "/".join(parts[:-1])
+        rand = parts[-1]
+        assert os.path.isdir(directory)
+        for filename in os.listdir(directory):
+            if rand in filename:
+                found_rand = True
+                if filename.endswith(".idx"):
+                    found_idx = True
+                elif filename.endswith(".pack"):
+                    found_pack = True
+            if found_rand and found_idx and found_pack:
+                break
+        else:
+            pytest.fail()
+    # CWD is not a temporary dir, so no deleted after using it.
+    assert os.path.isdir(directory)
+
+
 def test_git_client_upload_packfiles(git_repo):
     serializer = CIVisibilityGitClientSerializerV1("foo", "bar")
     remote_url = "[email protected]:test-repo-url.git"