fix(backend): determine active branch on startup (#9056)

* fix(backend): Determine active branch on startup

* add more warnings and document them

* extend expected errors

* fix typos

docs/docs/settings/error_codes.md

@@ -25,6 +25,24 @@ You probably have a reference to invoke or a directory with invoke in your PATH
 ### INVE-W (InvenTree Warning)
 Warnings - These are non-critical errors which should be addressed when possible.
 
+#### INVE-W1
+**Current branch could not be detected - Backend**
+
+During startup of the backend InvenTree tries to detect branch, commit hash and commit date to surface on various points in the UI, through tags and in the API.
+This information is not needed for operation but very helpful for debugging and support. These issues might be caused by running a deployment version that delivers without git information, not having git installed or not having dulwich installed.
+You can ignore this warning if you are not interested in the git information.
+
+#### INVE-W2
+**Dulwich module not found - Backend**
+
+See [INVE-W1](#inve-w1)
+
+#### INVE-W3
+**Could not detect git information - Backend**
+
+See [INVE-W1](#inve-w1)
+
+
 ### INVE-I (InvenTree Information)
 Information — These are not errors but information messages. They might point out potential issues or just provide information.
 

src/backend/InvenTree/InvenTree/version.py

@@ -26,19 +26,28 @@ logger = logging.getLogger('inventree')
 
 # Discover git
 try:
+    from dulwich.porcelain import active_branch
     from dulwich.repo import Repo
 
     main_repo = Repo(pathlib.Path(__file__).parent.parent.parent.parent.parent)
     main_commit = main_repo[main_repo.head()]
+    try:
+        main_branch = active_branch(main_repo)
+    except (KeyError, IndexError):
+        logger.warning('INVE-W1: Current branch could not be detected.')
+        main_branch = None
 except ImportError:
     logger.warning(
-        'Warning: Dulwich module not found, git information will not be available.'
+        'INVE-W2: Dulwich module not found, git information will not be available.'
     )
     main_repo = None
     main_commit = None
-except Exception:
+    main_branch = None
+except Exception as exc:
+    logger.warning('INVE-W3: Could not detect git information.', exc_info=exc)
     main_repo = None
     main_commit = None
+    main_branch = None
 
 
 def checkMinPythonVersion():
@@ -270,14 +279,9 @@ def inventreeBranch():
     if branch:
         return branch
 
-    if main_commit is None:
+    if main_branch is None:
         return None
-
-    try:
-        branch = main_repo.refs.follow(b'HEAD')[0][1].decode()
-        return branch.removeprefix('refs/heads/')
-    except IndexError:
-        return None  # pragma: no cover
+    return main_branch.decode('utf-8')
 
 
 def inventreeTarget():