minimal fastapi prom metrics (#1426)

* minimal fastapi prom metrics

inference/server/main.py

@@ -9,10 +9,18 @@ import websockets.exceptions
 from fastapi.middleware.cors import CORSMiddleware
 from loguru import logger
 from oasst_shared.schemas import inference, protocol
+from prometheus_fastapi_instrumentator import Instrumentator
 from sse_starlette.sse import EventSourceResponse
 
 app = fastapi.FastAPI()
 
+
+# add prometheus metrics at /metrics
+@app.on_event("startup")
+async def enable_prom_metrics():
+    Instrumentator().instrument(app).expose(app)
+
+
 # Allow CORS
 app.add_middleware(
     CORSMiddleware,

inference/server/requirements.txt

@@ -1,5 +1,6 @@
 fastapi[all]
 loguru
+prometheus-fastapi-instrumentator==5.9.1
 pydantic
 redis
 sse-starlette