codespaces: try codespaces system config if we can't get committer identity

src/scmrepo/git/backend/dulwich/__init__.py

@@ -291,12 +291,36 @@ def commit(self, msg: str, no_verify: bool = False):
             try:
                 commit(self.root_dir, message=msg, no_verify=no_verify)
             except InvalidUserIdentity as exc:
-                raise SCMError(
-                    "Git username and email must be configured"
-                ) from exc
+                identity = self._get_codespaces_identity()
+                if identity is not None:
+                    commit(
+                        self.root_dir,
+                        message=msg,
+                        no_verify=no_verify,
+                        committer=identity,
+                        author=identity,
+                    )
+                else:
+                    raise SCMError(
+                        "Git username and email must be configured"
+                    ) from exc
             except TimezoneFormatError as exc:
                 raise SCMError("Invalid Git timestamp") from exc
 
+    def _get_codespaces_identity(self) -> Optional[bytes]:
+        from dulwich.config import ConfigFile, StackedConfig
+        from dulwich.repo import get_user_identity
+
+        if "CODESPACES" not in os.environ:
+            return None
+        try:
+            config = StackedConfig(
+                [ConfigFile.from_path("/usr/local/etc/gitconfig")]
+            )
+            return get_user_identity(config)
+        except Exception:  # pylint: disable=broad-except
+            return None
+
     def checkout(
         self,
         branch: str,

src/scmrepo/git/backend/pygit2.py

@@ -15,7 +15,7 @@
     Union,
 )
 
-from funcy import cached_property
+from funcy import cached_property, first
 
 from scmrepo.exceptions import (
     CloneError,
@@ -32,6 +32,8 @@
 
 
 if TYPE_CHECKING:
+    from pygit2 import Signature
+
     from scmrepo.progress import GitProgressEvent
 
 
@@ -123,14 +125,32 @@ def _resolve_refish(self, refish: str):
         return commit, ref
 
     @property
-    def default_signature(self):
+    def default_signature(self) -> "Signature":
         try:
             return self.repo.default_signature
         except KeyError as exc:
+            signature = self._get_codespaces_signature()
+            if signature is not None:
+                return signature
             raise SCMError(
                 "Git username and email must be configured"
             ) from exc
 
+    def _get_codespaces_signature(self) -> Optional["Signature"]:
+        from pygit2 import Config, Signature
+
+        if "CODESPACES" not in os.environ:
+            return None
+        try:
+            config = Config("/usr/local/etc/gitconfig")
+            name = first(config.get_multivar("user.name"))
+            email = first(config.get_multivar("user.email"))
+            if name and email:
+                return Signature(name, email)
+        except Exception:  # pylint: disable=broad-except
+            pass
+        return None
+
     @staticmethod
     def _get_checkout_strategy(strategy: Optional[int] = None):
         from pygit2 import (