Disable _created metrics via dedicated built-in function

Added in prometheus/client_python#973

Author: MadLittleMods

-v

@@ -0,0 +1,9 @@
+HTTP/2 200 
+content-type: text/html
+etag: "84238dfc8092e5d9c0dac8ef93371a07:1736799080.121134"
+last-modified: Mon, 13 Jan 2025 20:11:20 GMT
+cache-control: max-age=702
+date: Fri, 20 Jun 2025 18:37:37 GMT
+alt-svc: h3=":443"; ma=93600,h3-29=":443"; ma=93600,quic=":443"; ma=93600; v="43"
+content-length: 1256
+

synapse/app/_base.py

@@ -283,28 +283,6 @@ async def wrapper() -> None:
     reactor.callWhenRunning(lambda: defer.ensureDeferred(wrapper()))
 
 
-def _set_prometheus_client_use_created_metrics(new_value: bool) -> None:
-    """
-    Sets whether prometheus_client should expose `_created`-suffixed metrics for
-    all gauges, histograms and summaries.
-    There is no programmatic way to disable this without poking at internals;
-    the proper way is to use an environment variable which prometheus_client
-    loads at import time.
-
-    The motivation for disabling these `_created` metrics is that they're
-    a waste of space as they're not useful but they take up space in Prometheus.
-    """
-
-    import prometheus_client.metrics
-
-    if hasattr(prometheus_client.metrics, "_use_created"):
-        prometheus_client.metrics._use_created = new_value
-    else:
-        logger.error(
-            "Can't disable `_created` metrics in prometheus_client (brittle hack broken?)"
-        )
-
-
 def listen_manhole(
     bind_addresses: StrCollection,
     port: int,

synapse/metrics/_twisted_exposition.py

@@ -20,13 +20,25 @@
 #
 #
 
-from prometheus_client import REGISTRY, CollectorRegistry, generate_latest
+from prometheus_client import (
+    REGISTRY,
+    CollectorRegistry,
+    generate_latest,
+    disable_created_metrics,
+)
 
 from twisted.web.resource import Resource
 from twisted.web.server import Request
 
 CONTENT_TYPE_LATEST = "text/plain; version=0.0.4; charset=utf-8"
 
+# Sets whether `prometheus_client` should expose `_created`-suffixed metrics for all
+# gauges, histograms and summaries.
+#
+# The motivation for disabling these `_created` metrics is that they're a waste of space
+# as they're not useful but they take up space in Prometheus.
+disable_created_metrics()
+
 
 class MetricsResource(Resource):
     """