Improved key-finding ability for Repository.initialize (#103)

* reproduce issue 102 and fix using extra_key_dirs

* make Keys.find_private_key() recursive

* use old-style typing for python 3.8 support

src/tufup/repo/__init__.py

@@ -260,16 +260,28 @@ def roles(self):
         return roles_map
 
     @classmethod
-    def find_private_key(cls, key_name: str, key_dirs: List[Union[pathlib.Path, str]]):
-        private_key_path = None
+    def find_private_key(
+        cls, key_name: str, key_dirs: List[Union[pathlib.Path, str]]
+    ) -> Optional[pathlib.Path]:
+        """
+        recursively search key_dirs for a private key with specified key_name
+
+        returns path to first matching file (or None)
+        """
         private_key_filename = cls.filename_pattern.format(key_name=key_name)
         for key_dir in key_dirs:
             key_dir = pathlib.Path(key_dir)  # ensure Path
             for path in key_dir.iterdir():
                 if path.is_file() and path.name == private_key_filename:
-                    private_key_path = path
-                    break
-        return private_key_path
+                    # base case
+                    return path
+                elif path.is_dir():
+                    # recursive case
+                    private_key_path = cls.find_private_key(
+                        key_name=key_name, key_dirs=[path]
+                    )
+                    if private_key_path:
+                        return private_key_path
 
 
 class Roles(Base):
@@ -614,7 +626,7 @@ def from_config(cls):
         instance._load_keys_and_roles(create_keys=False)
         return instance
 
-    def initialize(self):
+    def initialize(self, extra_key_dirs: Optional[List[pathlib.Path]] = None):
         """
         Initialize (or update) the local repository.
 
@@ -627,6 +639,8 @@ def initialize(self):
 
         Safe to call for existing keys and roles.
         """
+        extra_key_dirs = extra_key_dirs or []
+
         # Ensure dirs exist
         for path in [self.keys_dir, self.metadata_dir, self.targets_dir]:
             path.mkdir(parents=True, exist_ok=True)
@@ -636,7 +650,7 @@ def initialize(self):
 
         # Publish root metadata (save 1.root.json and copy to root.json)
         if not self.roles.file_path('root').exists():
-            self.publish_changes(private_key_dirs=[self.keys_dir])
+            self.publish_changes(private_key_dirs=[self.keys_dir] + extra_key_dirs)
 
     def refresh_expiration_date(self, role_name: str, days: Optional[int] = None):
         if days is None:

tests/test_repo.py

@@ -257,21 +257,22 @@ def test_find_private_key(self):
         # create dummy private key files in separate folders
         key_names = [
             ('online', [Snapshot.type, Timestamp.type]),
-            ('offline', [Root.type, Targets.type]),
+            ('offline/subdir', [Root.type, Targets.type]),  # subdir tests recursion
         ]
-        key_dirs = []
         for dir_name, role_names in key_names:
             dir_path = self.temp_dir_path / dir_name
-            dir_path.mkdir()
-            key_dirs.append(dir_path)
+            dir_path.mkdir(parents=True)
             for role_name in role_names:
                 filename = Keys.filename_pattern.format(key_name=role_name)
                 (dir_path / filename).touch()
         # test
+        key_dirs = list(self.temp_dir_path.iterdir())  # ['online', 'offline']
         for role_name in TOP_LEVEL_ROLE_NAMES:
             key_path = Keys.find_private_key(key_name=role_name, key_dirs=key_dirs)
+            self.assertTrue(key_path)
             self.assertIn(role_name, str(key_path))
             self.assertTrue(key_path.exists())
+        self.assertIsNone(Keys.find_private_key(key_name='missing', key_dirs=key_dirs))
 
 
 class RolesTests(TempDirTestCase):
@@ -611,6 +612,35 @@ def test_initialize(self):
             repo.roles.root.signed.expires.date(),
         )
 
+    def test_initialize_extra_key_dirs(self):
+        # prepare
+        repo = Repository(
+            app_name='test',
+            keys_dir=self.temp_dir_path / 'keystore',
+            repo_dir=self.temp_dir_path / 'repo',
+            expiration_days=DUMMY_EXPIRATION_DAYS,
+        )
+        repo.initialize()
+        # move private keys to separate dir
+        private_key_dir = self.temp_dir_path / 'private_keys'
+        private_key_dir.mkdir()
+        for path in repo.keys_dir.iterdir():
+            if path.is_file() and not path.suffix:
+                path.rename(target=private_key_dir / path.name)
+        # remove metadata files
+        for path in repo.metadata_dir.iterdir():
+            if path.suffix == '.json':
+                path.unlink()
+        # reproduce issue #102
+        with self.assertRaises(Exception) as context:
+            repo.initialize()
+        self.assertIn('no private keys found', str(context.exception).lower())
+        # test fix
+        try:
+            repo.initialize(extra_key_dirs=[private_key_dir])
+        except Exception as e:
+            self.fail(msg=f'unexpected exception: {e}')
+
     def test_refresh_expiration_date(self):
         repo = Repository(
             app_name='test',