Add support for collecting prometheus metrics

ooniapi/common/src/common/config.py

@@ -17,3 +17,4 @@ class Settings(BaseSettings):
     statsd_port: int = 8125
     statsd_prefix: str = "ooniapi"
     jwt_encryption_key: str = "CHANGEME"
+    prometheus_metrics_password: str = "CHANGEME"

ooniapi/common/src/common/metrics.py

@@ -0,0 +1,42 @@
+import secrets
+
+from typing import Annotated
+
+from fastapi import FastAPI, Response, Depends, HTTPException, status
+from fastapi.security import HTTPBasic, HTTPBasicCredentials
+
+from .dependencies import get_settings
+from prometheus_client import (
+    CONTENT_TYPE_LATEST,
+    CollectorRegistry,
+    generate_latest,
+)
+
+security = HTTPBasic()
+
+
+def mount_metrics(app: FastAPI, registry: CollectorRegistry):
+    def metrics(
+        credentials: Annotated[HTTPBasicCredentials, Depends(security)],
+        settings=Depends(get_settings),
+    ):
+        is_correct_username = secrets.compare_digest(
+            credentials.username.encode("utf8"), b"prom"
+        )
+        is_correct_password = secrets.compare_digest(
+            credentials.password.encode("utf8"),
+            settings.prometheus_metrics_password.encode("utf-8"),
+        )
+        if not (is_correct_username and is_correct_password):
+            raise HTTPException(
+                status_code=status.HTTP_401_UNAUTHORIZED,
+                detail="Incorrect username or password",
+                headers={"WWW-Authenticate": "Basic"},
+            )
+
+        resp = Response(content=generate_latest(registry))
+        resp.headers["Content-Type"] = CONTENT_TYPE_LATEST
+        return resp
+
+    endpoint = "/metrics"
+    app.get(endpoint, include_in_schema=True, tags=None)(metrics)

ooniapi/services/oonirun/pyproject.toml

@@ -21,6 +21,8 @@ dependencies = [
   "httpx ~= 0.26.0",
   "pyjwt ~= 2.8.0",
   "alembic ~= 1.13.1",
+  "prometheus-fastapi-instrumentator ~= 6.1.0",
+  "prometheus-client",
 ]
 
 readme = "README.md"

ooniapi/services/oonirun/src/oonirun/main.py

@@ -1,12 +1,14 @@
-from functools import lru_cache
 from fastapi import FastAPI
 
 from .routers import oonirun
 
 from .dependencies import get_settings
 from .common.version import get_build_label, get_pkg_version
+from .common.metrics import mount_metrics
 from fastapi.middleware.cors import CORSMiddleware
 
+from prometheus_fastapi_instrumentator import Instrumentator
+
 from contextlib import asynccontextmanager
 
 import logging
@@ -21,11 +23,16 @@
 async def lifespan(app: FastAPI):
     settings = get_settings()
     logging.basicConfig(level=getattr(logging, settings.log_level.upper()))
+    mount_metrics(app, instrumentor.registry)
     yield
 
 
 app = FastAPI(lifespan=lifespan)
 
+instrumentor = Instrumentator().instrument(
+    app, metric_namespace="ooniapi", metric_subsystem="oonirun"
+)
+
 # TODO: temporarily enable all
 origins = ["*"]
 app.add_middleware(

ooniapi/services/oonirun/src/oonirun/routers/oonirun.py

@@ -5,9 +5,7 @@
 """
 
 from datetime import datetime, timedelta, timezone, date
-from os import urandom
-from sys import byteorder
-from typing import Dict, Any, List, Optional, Tuple
+from typing import Dict, List, Optional, Tuple
 import logging
 
 import sqlalchemy as sa
@@ -17,7 +15,6 @@
 from pydantic import BaseModel as PydandicBaseModel
 from typing_extensions import Annotated
 
-
 from .. import models
 
 from ..common.dependencies import get_settings, role_required
@@ -28,7 +25,6 @@
 )
 from ..dependencies import get_postgresql_session
 
-
 ISO_FORMAT_DATETIME = "%Y-%m-%dT%H:%M:%S.%fZ"
 ISO_FORMAT_DATE = "%Y-%m-%d"