1 files changed, 38 insertions, 0 deletions
diff --git a/synapse/metrics/_twisted_exposition.py b/synapse/metrics/_twisted_exposition.py
new file mode 100644
index 0000000000..0abcd14953
--- /dev/null
+++ b/synapse/metrics/_twisted_exposition.py
@@ -0,0 +1,38 @@
+# Copyright 2015-2019 Prometheus Python Client Developers
+# Copyright 2019 Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from prometheus_client import REGISTRY, CollectorRegistry, generate_latest
+
+from twisted.web.resource import Resource
+from twisted.web.server import Request
+
+CONTENT_TYPE_LATEST = "text/plain; version=0.0.4; charset=utf-8"
+
+
+class MetricsResource(Resource):
+    """
+    Twisted ``Resource`` that serves prometheus metrics.
+    """
+
+    isLeaf = True
+
+    def __init__(self, registry: CollectorRegistry = REGISTRY):
+        self.registry = registry
+
+    def render_GET(self, request: Request) -> bytes:
+        request.setHeader(b"Content-Type", CONTENT_TYPE_LATEST.encode("ascii"))
+        response = generate_latest(self.registry)
+        request.setHeader(b"Content-Length", str(len(response)))
+        return response