feat: add an option to update certain metadata files when signing tar…

…get files, even if no targets were modified

taf/api/targets.py

@@ -329,6 +329,7 @@ def register_target_files(
     no_commit_warning: Optional[bool] = True,
     reset_updated_targets_on_error: Optional[bool] = False,
     commit_msg: Optional[str] = None,
+    force_update_of_roles: Optional[str] = None,
 ):
     """
     Register all files found in the target directory as targets - update the targets
@@ -338,12 +339,14 @@ def register_target_files(
         path: Authentication repository's path.
         keystore: Location of the keystore files.
         roles_key_infos: A dictionary whose keys are role names, while values contain information about the keys.
-    scheme (optional): Signing scheme. Set to rsa-pkcs1v15-sha256 by default.
+        scheme (optional): Signing scheme. Set to rsa-pkcs1v15-sha256 by default.
         auth_repo (optional): If auth repository is already initialized, it can be passed and used.
         write (optional): Write metadata updates to disk if set to True
         commit (optional): Indicates if the changes should be committed and pushed automatically.
         prompt_for_keys (optional): Whether to ask the user to enter their key if it is not located inside the keystore directory.
         push (optional): Flag specifying whether to push to remote
+        force_update_of_roles (optional): A list of roles whose version should be updated, even
+        if no other changes are made
     Side Effects:
        Updates metadata files, writes changes to disk and optionally commits changes.
 
@@ -376,9 +379,14 @@ def register_target_files(
         roles_key_infos, keystore, enter_info=False
     )
 
+    roles_to_load = list(roles_and_targets.keys())
+    if force_update_of_roles:
+        for role in force_update_of_roles:
+            if role not in roles_to_load:
+                roles_to_load.append(role)
     with manage_repo_and_signers(
         auth_repo,
-        list(roles_and_targets.keys()),
+        roles_to_load,
         keystore,
         scheme,
         prompt_for_keys,
@@ -394,6 +402,11 @@ def register_target_files(
     ):
         for role, targets in roles_and_targets.items():
             auth_repo.update_target_role(role, targets)
+        if force_update_of_roles:
+            for role in force_update_of_roles:
+                if role not in roles_and_targets:
+                    auth_repo.update_target_role(role, None, True)
+
         if update_snapshot_and_timestamp:
             auth_repo.update_snapshot_and_timestamp()
 

taf/tuf/repository.py

@@ -1608,29 +1608,35 @@ def sync_snapshot_with_roles(self, roles: List[str]) -> None:
             for role in roles:
                 sn.meta[f"{role}.json"].version = sn.meta[f"{role}.json"].version + 1
 
-    def update_target_role(self, role: str, target_paths: Dict):
+    def update_target_role(self, role: str, target_paths: Dict, force=False):
         """
         Update the specified target role by adding or removing
         target files and target objects for the specified target paths
+        If false is True, update the metadata files even if no target
+        paths are specified
         """
         if not self.check_if_role_exists(role):
             raise TAFError(f"Role {role} does not exist")
         self.verify_signers_loaded([role])
         removed_paths = []
         target_files = []
-        for target_path in target_paths:
-            full_path = self.path / TARGETS_DIRECTORY_NAME / target_path
-            # file removed, removed from te role
-            if not full_path.is_file():
-                removed_paths.append(target_path)
-            else:
-                custom_data = self.get_target_file_custom_data(target_path)
-                target_file = self._create_target_object(
-                    full_path, target_path, custom_data
-                )
-                target_files.append(target_file)
+        if target_paths:
+            for target_path in target_paths:
+                full_path = self.path / TARGETS_DIRECTORY_NAME / target_path
+                # file removed, removed from te role
+                if not full_path.is_file():
+                    removed_paths.append(target_path)
+                else:
+                    custom_data = self.get_target_file_custom_data(target_path)
+                    target_file = self._create_target_object(
+                        full_path, target_path, custom_data
+                    )
+                    target_files.append(target_file)
 
-        self._modify_targets_role(target_files, removed_paths, role)
+            self._modify_targets_role(target_files, removed_paths, role)
+        elif force:
+            with self.edit(role) as _:
+                pass
 
     def update_snapshot_and_timestamp(self, force: Optional[bool] = True):
         """