fix: check git env vars before using the command on the source code integration [backport 3.12] (#14619)

Backport d2812f2 from #14613 to 3.12.

The sourcecode integration was using git to retrieve the commit hash and
repository url. However, we already have defined `DD_GIT_COMMIT_HASH`
and `DD_GIT_REPOSITORY_URL` for these cases, so check these vars before.

## Checklist
- [X] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Signed-off-by: Juanjo Alvarez <juanjo.alvarezmartinez@datadoghq.com>
Co-authored-by: Juanjo Alvarez Martinez <juanjo.alvarezmartinez@datadoghq.com>

Author: dd-octo-sts[bot]

ddtrace/sourcecode/_utils.py

@@ -1,5 +1,5 @@
+import os
 import re
-import subprocess
 from urllib import parse
 
 
@@ -56,15 +56,23 @@ def normalize_repository_url(url):
 
 
 def _query_git(args):
+    import subprocess  # don't import subprocess (and maybe activate the integration) if not needed
+
     ver = subprocess.Popen(["git"] + args, stdout=subprocess.PIPE).communicate()[0]
     return ver.strip().decode("utf-8")
 
 
 def get_commit_sha():
+    commit_sha = os.environ.get("DD_GIT_COMMIT_SHA")
+    if commit_sha:
+        return commit_sha
     return _query_git(["rev-parse", "HEAD"])
 
 
 def get_repository_url():
+    repository_url = os.environ.get("DD_GIT_REPOSITORY_URL")
+    if repository_url:
+        return repository_url
     return _query_git(["config", "--get", "remote.origin.url"])
 
 

releasenotes/notes/sourcecode-check-env-vars-cab3d9b6311c2695.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    source code integration: check that ``DD_GIT_COMMIT_SHA`` and ``DD_GIT_REPOSITORY_URL`` are defined before
+    using the git command.

tests/sourcecode/test_source_code_env_vars.py

@@ -0,0 +1,55 @@
+import os
+from unittest import mock
+
+from ddtrace.sourcecode._utils import get_commit_sha
+from ddtrace.sourcecode._utils import get_repository_url
+
+
+class TestSourceCodeEnvVars:
+    def test_get_commit_sha_uses_env_var_when_present(self):
+        test_sha = "abc123def456"
+        with mock.patch.dict(os.environ, {"DD_GIT_COMMIT_SHA": test_sha}):
+            with mock.patch("ddtrace.sourcecode._utils._query_git") as mock_git:
+                result = get_commit_sha()
+                assert result == test_sha
+                mock_git.assert_not_called()
+
+    def test_get_commit_sha_calls_git_when_env_var_not_present(self):
+        test_sha = "git_result_sha"
+        with mock.patch.dict(os.environ, {}, clear=True):
+            with mock.patch("ddtrace.sourcecode._utils._query_git", return_value=test_sha) as mock_git:
+                result = get_commit_sha()
+                assert result == test_sha
+                mock_git.assert_called_once_with(["rev-parse", "HEAD"])
+
+    def test_get_commit_sha_calls_git_when_env_var_empty(self):
+        test_sha = "git_result_sha"
+        with mock.patch.dict(os.environ, {"DD_GIT_COMMIT_SHA": ""}):
+            with mock.patch("ddtrace.sourcecode._utils._query_git", return_value=test_sha) as mock_git:
+                result = get_commit_sha()
+                assert result == test_sha
+                mock_git.assert_called_once_with(["rev-parse", "HEAD"])
+
+    def test_get_repository_url_uses_env_var_when_present(self):
+        test_url = "https://github.com/user/repo.git"
+        with mock.patch.dict(os.environ, {"DD_GIT_REPOSITORY_URL": test_url}):
+            with mock.patch("ddtrace.sourcecode._utils._query_git") as mock_git:
+                result = get_repository_url()
+                assert result == test_url
+                mock_git.assert_not_called()
+
+    def test_get_repository_url_calls_git_when_env_var_not_present(self):
+        test_url = "git_result_url"
+        with mock.patch.dict(os.environ, {}, clear=True):
+            with mock.patch("ddtrace.sourcecode._utils._query_git", return_value=test_url) as mock_git:
+                result = get_repository_url()
+                assert result == test_url
+                mock_git.assert_called_once_with(["config", "--get", "remote.origin.url"])
+
+    def test_get_repository_url_calls_git_when_env_var_empty(self):
+        test_url = "git_result_url"
+        with mock.patch.dict(os.environ, {"DD_GIT_REPOSITORY_URL": ""}):
+            with mock.patch("ddtrace.sourcecode._utils._query_git", return_value=test_url) as mock_git:
+                result = get_repository_url()
+                assert result == test_url
+                mock_git.assert_called_once_with(["config", "--get", "remote.origin.url"])