fix: use explicit commit hash for docker package versioning (#856)

version.py

@@ -3,6 +3,7 @@ SPDX-FileCopyrightText: © Sebastian Thomschke and contributors
 SPDX-License-Identifier: AGPL-3.0-or-later
 SPDX-ArtifactOfProjectHomePage: https://github.com/Second-Hand-Friends/kleinanzeigen-bot/
 """
+import os
 import shutil
 import subprocess
 from datetime import datetime, timezone
@@ -10,14 +11,21 @@ from datetime import datetime, timezone
 
 # used in pyproject.toml [tool.pdm.version]
 def get_version() -> str:
+    commit_hash = os.environ.get("GIT_COMMIT_HASH", "").strip()
+    if commit_hash:
+        return f"{datetime.now(timezone.utc).year}+{commit_hash}"
+
     git = shutil.which("git")
     if git is None:
-        raise RuntimeError("git executable not found, unable to compute version")
-    result = subprocess.run(  # noqa: S603 running git is safe here
-        [git, "rev-parse", "--short", "HEAD"],
-        check=True,
-        capture_output=True,
-        text=True,
-    )
+        raise RuntimeError("unable to compute version: set GIT_COMMIT_HASH or build from a valid git checkout")
+    try:
+        result = subprocess.run(  # noqa: S603 running git is safe here
+            [git, "rev-parse", "--short", "HEAD"],
+            check=True,
+            capture_output=True,
+            text=True,
+        )
+    except subprocess.CalledProcessError as ex:
+        raise RuntimeError("unable to compute version: set GIT_COMMIT_HASH or build from a valid git checkout") from ex
     commit_hash = result.stdout.strip()
     return f"{datetime.now(timezone.utc).year}+{commit_hash}"