Sync from v0.13

vllm/entrypoints/serve/instrumentator/metrics.py

@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+
+import prometheus_client
+import regex as re
+from fastapi import FastAPI, Response
+from prometheus_client import make_asgi_app
+from prometheus_fastapi_instrumentator import Instrumentator
+from starlette.routing import Mount
+
+from vllm.v1.metrics.prometheus import get_prometheus_registry
+
+
+class PrometheusResponse(Response):
+    media_type = prometheus_client.CONTENT_TYPE_LATEST
+
+
+def attach_router(app: FastAPI):
+    """Mount prometheus metrics to a FastAPI app."""
+
+    registry = get_prometheus_registry()
+
+    # `response_class=PrometheusResponse` is needed to return an HTTP response
+    # with header "Content-Type: text/plain; version=0.0.4; charset=utf-8"
+    # instead of the default "application/json" which is incorrect.
+    # See https://github.com/trallnag/prometheus-fastapi-instrumentator/issues/163#issue-1296092364
+    Instrumentator(
+        excluded_handlers=[
+            "/metrics",
+            "/health",
+            "/load",
+            "/ping",
+            "/version",
+            "/server_info",
+        ],
+        registry=registry,
+    ).add().instrument(app).expose(app, response_class=PrometheusResponse)
+
+    # Add prometheus asgi middleware to route /metrics requests
+    metrics_route = Mount("/metrics", make_asgi_app(registry=registry))
+
+    # Workaround for 307 Redirect for /metrics
+    metrics_route.path_regex = re.compile("^/metrics(?P<path>.*)$")
+    app.routes.append(metrics_route)