Deprecate the `generate_short_term_login_token` method in favor of an async `create_login_token` method in the Module API. (#13842)

Signed-off-by: Quentin Gliech <quenting@element.io>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

3 files changed, 76 insertions, 0 deletions

diff --git a/changelog.d/13842.removal b/changelog.d/13842.removal
new file mode 100644
index 0000000000..cbcff38e91
--- /dev/null
+++ b/changelog.d/13842.removal
@@ -0,0 +1 @@
+Deprecate the `generate_short_term_login_token` method in favor of an async `create_login_token` method in the Module API.
diff --git a/docs/upgrade.md b/docs/upgrade.md
index 002ef70059..b81385b191 100644
--- a/docs/upgrade.md
+++ b/docs/upgrade.md
@@ -128,6 +128,39 @@ you may specify `enable_legacy_metrics: false` in your homeserver configuration.
 A list of affected metrics is available on the [Metrics How-to page](https://matrix-org.github.io/synapse/v1.69/metrics-howto.html?highlight=metrics%20deprecated#renaming-of-metrics--deprecation-of-old-names-in-12).
 
 
+## Deprecation of the `generate_short_term_login_token` module API method
+
+The following method of the module API has been deprecated, and is scheduled to
+be remove in v1.71.0:
+
+```python
+def generate_short_term_login_token(
+    self,
+    user_id: str,
+    duration_in_ms: int = (2 * 60 * 1000),
+    auth_provider_id: str = "",
+    auth_provider_session_id: Optional[str] = None,
+) -> str:
+    ...
+```
+
+It has been replaced by an asynchronous equivalent:
+
+```python
+async def create_login_token(
+    self,
+    user_id: str,
+    duration_in_ms: int = (2 * 60 * 1000),
+    auth_provider_id: Optional[str] = None,
+    auth_provider_session_id: Optional[str] = None,
+) -> str:
+    ...
+```
+
+Synapse will log a warning when a module uses the deprecated method, to help
+administrators find modules using it.
+
+
 # Upgrading to v1.68.0
 
 Two changes announced in the upgrade notes for v1.67.0 have now landed in v1.68.0.
diff --git a/synapse/module_api/__init__.py b/synapse/module_api/__init__.py
index b7b2d3b8c5..6a6ae208d1 100644
--- a/synapse/module_api/__init__.py
+++ b/synapse/module_api/__init__.py
@@ -748,6 +748,40 @@ class ModuleApi:
             )
         )
 
+    async def create_login_token(
+        self,
+        user_id: str,
+        duration_in_ms: int = (2 * 60 * 1000),
+        auth_provider_id: Optional[str] = None,
+        auth_provider_session_id: Optional[str] = None,
+    ) -> str:
+        """Create a login token suitable for m.login.token authentication
+
+        Added in Synapse v1.69.0.
+
+        Args:
+            user_id: gives the ID of the user that the token is for
+
+            duration_in_ms: the time that the token will be valid for
+
+            auth_provider_id: the ID of the SSO IdP that the user used to authenticate
+                to get this token, if any. This is encoded in the token so that
+                /login can report stats on number of successful logins by IdP.
+
+            auth_provider_session_id: The session ID got during login from the SSO IdP,
+                if any.
+        """
+        # The deprecated `generate_short_term_login_token` method defaulted to an empty
+        # string for the `auth_provider_id` because of how the underlying macaroon was
+        # generated. This will change to a proper NULL-able field when the tokens get
+        # moved to the database.
+        return self._hs.get_macaroon_generator().generate_short_term_login_token(
+            user_id,
+            auth_provider_id or "",
+            auth_provider_session_id,
+            duration_in_ms,
+        )
+
     def generate_short_term_login_token(
         self,
         user_id: str,
@@ -759,6 +793,9 @@ class ModuleApi:
 
         Added in Synapse v1.9.0.
 
+        This was deprecated in Synapse v1.69.0 in favor of create_login_token, and will
+        be removed in Synapse 1.71.0.
+
         Args:
             user_id: gives the ID of the user that the token is for
 
@@ -768,6 +805,11 @@ class ModuleApi:
                to get this token, if any. This is encoded in the token so that
                /login can report stats on number of successful logins by IdP.
         """
+        logger.warn(
+            "A module configured on this server uses ModuleApi.generate_short_term_login_token(), "
+            "which is deprecated in favor of ModuleApi.create_login_token(), and will be removed in "
+            "Synapse 1.71.0",
+        )
         return self._hs.get_macaroon_generator().generate_short_term_login_token(
             user_id,
             auth_provider_id,