Remove metrics listener type in favor of http listener with metrics resource

docs/metrics-howto.md

@@ -53,15 +53,17 @@
         type: http
         x_forwarded: true
         bind_addresses: ['::1', '127.0.0.1']
-
         resources:
           - names: [client, federation]
             compress: false
 
       # beginning of the new metrics listener
       - port: 9000
-        type: metrics
+        type: http
         bind_addresses: ['::1', '127.0.0.1']
+        resources:
+          - names: [metrics]
+            compress: false
     ```
 
 1.  Restart Synapse.

docs/usage/configuration/config_documentation.md

@@ -513,8 +513,6 @@ See the docs [request log format](../administration/request_log.md).
 
    * `manhole`: (see the docs [here](../../manhole.md)),
 
-   * `metrics`: (see the docs [here](../../metrics-howto.md)),
-
 * `tls`: set to true to enable TLS for this listener. Will use the TLS key/cert specified in tls_private_key_path / tls_certificate_path.
 
 * `x_forwarded`: Only valid for an 'http' listener. Set to true to use the X-Forwarded-For header as the client IP. Useful when Synapse is

synapse/app/_base.py

@@ -283,20 +283,6 @@ def register_start(
     reactor.callWhenRunning(lambda: defer.ensureDeferred(wrapper()))
 
 
-def listen_metrics(bind_addresses: StrCollection, port: int) -> None:
-    """
-    Start Prometheus metrics server.
-    """
-    from prometheus_client import start_http_server as start_http_server_prometheus
-
-    from synapse.metrics import RegistryProxy
-
-    for host in bind_addresses:
-        logger.info("Starting metrics listener on %s:%d", host, port)
-        _set_prometheus_client_use_created_metrics(False)
-        start_http_server_prometheus(port, addr=host, registry=RegistryProxy)
-
-
 def _set_prometheus_client_use_created_metrics(new_value: bool) -> None:
     """
     Sets whether prometheus_client should expose `_created`-suffixed metrics for

synapse/app/generic_worker.py

@@ -49,7 +49,7 @@ from synapse.config.server import ListenerConfig, TCPListenerConfig
 from synapse.federation.transport.server import TransportLayerServer
 from synapse.http.server import JsonResource, OptionsResource
 from synapse.logging.context import LoggingContext
-from synapse.metrics import METRICS_PREFIX, MetricsResource, RegistryProxy
+from synapse.metrics import METRICS_PREFIX, MetricsResource
 from synapse.replication.http import REPLICATION_PREFIX, ReplicationRestResource
 from synapse.rest import ClientRestResource, admin
 from synapse.rest.health import HealthResource
@@ -186,7 +186,9 @@ class GenericWorkerServer(HomeServer):
         for res in listener_config.http_options.resources:
             for name in res.names:
                 if name == "metrics":
-                    resources[METRICS_PREFIX] = MetricsResource(RegistryProxy)
+                    resources[METRICS_PREFIX] = MetricsResource(
+                        self.metrics_collector_registry
+                    )
                 elif name == "client":
                     resource: Resource = ClientRestResource(self)
 
@@ -284,23 +286,6 @@ class GenericWorkerServer(HomeServer):
                         "Can not using a unix socket for manhole at this time."
                     )
 
-            elif listener.type == "metrics":
-                if not self.config.metrics.enable_metrics:
-                    logger.warning(
-                        "Metrics listener configured, but "
-                        "enable_metrics is not True!"
-                    )
-                else:
-                    if isinstance(listener, TCPListenerConfig):
-                        _base.listen_metrics(
-                            listener.bind_addresses,
-                            listener.port,
-                        )
-                    else:
-                        raise ConfigError(
-                            "Can not use a unix socket for metrics at this time."
-                        )
-
             else:
                 logger.warning("Unsupported listener type: %s", listener.type)
 

synapse/app/homeserver.py

@@ -288,22 +288,6 @@ class SynapseHomeServer(HomeServer):
                     raise ConfigError(
                         "Can not use a unix socket for manhole at this time."
                     )
-            elif listener.type == "metrics":
-                if not self.config.metrics.enable_metrics:
-                    logger.warning(
-                        "Metrics listener configured, but "
-                        "enable_metrics is not True!"
-                    )
-                else:
-                    if isinstance(listener, TCPListenerConfig):
-                        _base.listen_metrics(
-                            listener.bind_addresses,
-                            listener.port,
-                        )
-                    else:
-                        raise ConfigError(
-                            "Can not use a unix socket for metrics at this time."
-                        )
 
             else:
                 # this shouldn't happen, as the listener type should have been checked

synapse/metrics/__init__.py

@@ -67,21 +67,6 @@ all_gauges: Dict[str, Collector] = {}
 HAVE_PROC_SELF_STAT = os.path.exists("/proc/self/stat")
 
 
-class _RegistryProxy:
-    @staticmethod
-    def collect() -> Iterable[Metric]:
-        for metric in REGISTRY.collect():
-            if not metric.name.startswith("__"):
-                yield metric
-
-
-# A little bit nasty, but collect() above is static so a Protocol doesn't work.
-# _RegistryProxy matches the signature of a CollectorRegistry instance enough
-# for it to be usable in the contexts in which we use it.
-# TODO Do something nicer about this.
-RegistryProxy = cast(CollectorRegistry, _RegistryProxy)
-
-
 @attr.s(slots=True, hash=True, auto_attribs=True)
 class LaterGauge(Collector):
     """A Gauge which periodically calls a user-provided callback to produce metrics."""