Repository: matrix-org/synapse

Issue:
prometheus metrics to track registration/login success rates
If we had prometheus metrics to track numbers of new registrations and numbers of successful logins (ideally broken down by identity provider), it might provide good early warning of problems in this fragile area.


Discussion:
this should be really easy. est 0.5d.

Resolving patch:
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -18,6 +18,8 @@
 import logging
 from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple
 
+from prometheus_client import Counter
+
 from synapse import types
 from synapse.api.constants import MAX_USERID_LENGTH, EventTypes, JoinRules, LoginType
 from synapse.api.errors import AuthError, Codes, ConsentNotGivenError, SynapseError
@@ -41,6 +43,19 @@
 logger = logging.getLogger(__name__)
 
 
+registration_counter = Counter(
+    "synapse_user_registrations_total",
+    "Number of new users registered (since restart)",
+    ["guest", "shadow_banned", "auth_provider"],
+)
+
+login_counter = Counter(
+    "synapse_user_logins_total",
+    "Number of user logins (since restart)",
+    ["guest", "auth_provider"],
+)
+
+
 class RegistrationHandler(BaseHandler):
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
@@ -156,6 +171,7 @@ async def register_user(
         bind_emails: Iterable[str] = [],
         by_admin: bool = False,
         user_agent_ips: Optional[List[Tuple[str, str]]] = None,
+        auth_provider_id: Optional[str] = None,
     ) -> str:
         """Registers a new client on the server.
 
@@ -181,8 +197,10 @@ async def register_user(
               admin api, otherwise False.
             user_agent_ips: Tuples of IP addresses and user-agents used
                 during the registration process.
+            auth_provider_id: The SSO IdP the user used, if any (just used for the
+                prometheus metrics).
         Returns:
-            The registere user_id.
+            The registered user_id.
         Raises:
             SynapseError if there was a problem registering.
         """
@@ -280,6 +298,12 @@ async def register_user(
                     # if user id is taken, just generate another
                     fail_count += 1
 
+        registration_counter.labels(
+            guest=make_guest,
+            shadow_banned=shadow_banned,
+            auth_provider=(auth_provider_id or ""),
+        ).inc()
+
         if not self.hs.config.user_consent_at_registration:
             if not self.hs.config.auto_join_rooms_for_guests and make_guest:
                 logger.info(
@@ -638,6 +662,7 @@ async def register_device(
         initial_display_name: Optional[str],
         is_guest: bool = False,
         is_appservice_ghost: bool = False,
+        auth_provider_id: Optional[str] = None,
     ) -> Tuple[str, str]:
         """Register a device for a user and generate an access token.
 
@@ -648,7 +673,8 @@ async def register_device(
             device_id: The device ID to check, or None to generate a new one.
             initial_display_name: An optional display name for the device.
             is_guest: Whether this is a guest account
-
+            auth_provider_id: The SSO IdP the user used, if any (just used for the
+                prometheus metrics).
         Returns:
             Tuple of device ID and access token
         """
@@ -687,6 +713,11 @@ async def register_device(
                 is_appservice_ghost=is_appservice_ghost,
             )
 
+        login_counter.labels(
+            guest=is_guest,
+            auth_provider=(auth_provider_id or ""),
+        ).inc()
+
         return (registered_device_id, access_token)
 
     async def post_registration_actions(
diff --git a/synapse/handlers/sso.py b/synapse/handlers/sso.py
--- a/synapse/handlers/sso.py
+++ b/synapse/handlers/sso.py
@@ -606,6 +606,7 @@ async def _register_mapped_user(
             default_display_name=attributes.display_name,
             bind_emails=attributes.emails,
             user_agent_ips=[(user_agent, ip_address)],
+            auth_provider_id=auth_provider_id,
         )
 
         await self._store.record_user_external_id(
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -219,6 +219,7 @@ async def _complete_login(
         callback: Optional[Callable[[Dict[str, str]], Awaitable[None]]] = None,
         create_non_existent_users: bool = False,
         ratelimit: bool = True,
+        auth_provider_id: Optional[str] = None,
     ) -> Dict[str, str]:
         """Called when we've successfully authed the user and now need to
         actually login them in (e.g. create devices). This gets called on
@@ -234,6 +235,8 @@ async def _complete_login(
             create_non_existent_users: Whether to create the user if they don't
                 exist. Defaults to False.
             ratelimit: Whether to ratelimit the login request.
+            auth_provider_id: The SSO IdP the user used, if any (just used for the
+                prometheus metrics).
 
         Returns:
             result: Dictionary of account information after successful login.
@@ -256,7 +259,7 @@ async def _complete_login(
         device_id = login_submission.get("device_id")
         initial_display_name = login_submission.get("initial_device_display_name")
         device_id, access_token = await self.registration_handler.register_device(
-            user_id, device_id, initial_display_name
+            user_id, device_id, initial_display_name, auth_provider_id=auth_provider_id
         )
 
         result = {
@@ -286,7 +289,10 @@ async def _do_token_login(self, login_submission: JsonDict) -> Dict[str, str]:
         res = await auth_handler.validate_short_term_login_token(token)
 
         return await self._complete_login(
-            res.user_id, login_submission, self.auth_handler._sso_login_callback
+            res.user_id,
+            login_submission,
+            self.auth_handler._sso_login_callback,
+            auth_provider_id=res.auth_provider_id,
         )
 
     async def _do_jwt_login(self, login_submission: JsonDict) -> Dict[str, str]:


Test patch: