Add basic HTTP metrics

battleship/server/app.py

@@ -18,6 +18,10 @@
     PlayerSubscriptionHandler,
     SessionSubscriptionHandler,
 )
+from battleship.server.metrics import (
+    MetricsMiddleware,
+    MetricsScraperAuthenticationHandler,
+)
 from battleship.server.pubsub import (
     IncomingChannel,
     IncomingRedisChannel,
@@ -82,7 +86,11 @@ async def sentry_context_middleware(
 
     if identity and identity.is_authenticated():
         sentry_sdk.set_user(
-            {"id": identity.sub, "username": identity["nickname"], "email": identity["email"]}
+            {
+                "id": identity.sub,
+                "username": identity.get("nickname"),
+                "email": identity.get("email"),
+            }
         )
 
     return await handler(request)
@@ -115,6 +123,10 @@ def create_app() -> Any:
         )
     )
 
+    app.use_authentication().add(
+        MetricsScraperAuthenticationHandler(scraper_secret=config.METRICS_SCRAPER_SECRET)
+    )
+
     app.use_authorization().with_default_policy(
         Policy("authenticated", AuthenticatedRequirement()),
     )
@@ -124,7 +136,16 @@ def create_app() -> Any:
 
     app.middlewares.append(client_version_middleware)
     app.middlewares.append(sentry_context_middleware)
+    app_router = app.router
 
     if config.SENTRY_DSN:
-        return configure_sentry(app, config.SENTRY_DSN, config.SERVER_VERSION)
+        app = configure_sentry(
+            app,
+            config.SENTRY_DSN,
+            config.SERVER_VERSION,
+        )  # type: ignore[assignment]
+
+    if config.METRICS_SCRAPER_SECRET:
+        app = MetricsMiddleware(app, router=app_router)  # type: ignore[assignment]
+
     return app

battleship/server/config.py

@@ -12,6 +12,7 @@ class Config(BaseSettings):
     BROKER_URL: RedisDsn
     SERVER_VERSION: str
     SENTRY_DSN: str
+    METRICS_SCRAPER_SECRET: str
 
     @property
     def auth0_audience(self) -> str:

battleship/server/metrics.py

@@ -0,0 +1,72 @@
+from typing import Any
+
+from aioprometheus.asgi.middleware import MetricsMiddleware as _MetricsMiddleware
+from aioprometheus.asgi.middleware import Receive, Scope, Send
+from aioprometheus.collectors import REGISTRY
+from aioprometheus.renderer import render
+from blacksheep import Request, Router
+from guardpost import AuthenticationHandler, Identity
+
+__all__ = [
+    "MetricsMiddleware",
+    "MetricsScraperAuthenticationHandler",
+    "render_metrics",
+]
+
+
+class MetricsScraperAuthenticationHandler(AuthenticationHandler):
+    def __init__(self, scraper_secret: str):
+        self._secret = scraper_secret.encode()
+
+    def authenticate(self, context: Request) -> Identity | None:
+        header_value = context.get_first_header(b"Authorization")
+
+        try:
+            type_, secret = header_value.split()  # type: ignore[union-attr]
+        except Exception:
+            context.identity = None
+        else:
+            if type_ == b"Bearer" and secret == self._secret:
+                context.identity = Identity({"id": "scraper"}, authentication_mode="Bearer")
+            else:
+                context.identity = None
+
+        return context.identity
+
+
+class MetricsMiddleware(_MetricsMiddleware):
+    """
+    ioprometheus.MetricsMiddleware that doesn't fail on WebSocket connections
+    and extracts template paths from Blacksheep.
+    """
+
+    def __init__(self, *args: Any, router: Router, **kwargs: Any):
+        super().__init__(*args, **kwargs)
+        self.router = router
+
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
+        if scope["type"] == "websocket":
+            await self.asgi_callable(scope, receive, send)
+            return
+
+        await super().__call__(scope, receive, send)
+
+    def get_full_or_template_path(self, scope: Scope) -> str:
+        root_path = scope.get("root_path", "")
+        path = scope.get("path", "")
+        full_path = f"{root_path}{path}"
+        method = scope.get("method", "").upper()
+
+        if self.use_template_urls:
+            match = self.router.get_match_by_method_and_path(method, path)
+
+            if match is not None:
+                return match.pattern.decode()
+        return full_path
+
+
+def render_metrics(accept_headers: list[bytes]) -> tuple[str, dict[bytes, bytes]]:
+    accept_headers_decoded = [value.decode() for value in accept_headers]
+    content, headers = render(REGISTRY, accept_headers_decoded)
+    headers = {k.encode(): v.encode() for k, v in headers.items()}
+    return content.decode(), headers

battleship/server/routes.py

@@ -2,6 +2,7 @@
 
 from blacksheep import (
     FromJSON,
+    Request,
     Response,
     Router,
     WebSocket,
@@ -22,6 +23,7 @@
     PlayerSubscriptionHandler,
     SessionSubscriptionHandler,
 )
+from battleship.server.metrics import render_metrics
 from battleship.server.pubsub import IncomingChannel, OutgoingChannel
 from battleship.server.repositories import (
     ClientRepository,
@@ -41,7 +43,7 @@
     SignupCredentials,
 )
 
-router = Router()  # type: ignore[no-untyped-call]
+router = Router()
 
 
 @router.ws("/ws")
@@ -231,3 +233,12 @@ async def get_player_statistics(
         statistics = await statistics_repository.create(user_id)
 
     return ok(statistics.to_dict())
+
+
+@router.get("/metrics")
+async def get_metrics(request: Request) -> Response:
+    accept_headers = request.get_headers(b"Accept")
+    content, headers = render_metrics(accept_headers)
+    response = ok(content)
+    response.headers.add_many(headers)
+    return response

pyproject.toml

@@ -47,10 +47,11 @@ textual-dev = { version = "^1.2.1", optional = true }
 async-timeout = { version = "^4.0.3", optional = true, markers = "python_version < '3.11'" }
 backports-strenum = { version = "^1.2.8", markers = "python_version < '3.11'" }
 sentry-sdk = { version = "^1.38.0", optional = true }
+aioprometheus = {version = "^23.3.0", optional = true}
 
 
 [tool.poetry.extras]
-server = ["blacksheep", "uvicorn", "auth0-python", "pyjwt", "uvloop", "redis", "sentry-sdk"]
+server = ["blacksheep", "uvicorn", "auth0-python", "pyjwt", "uvloop", "redis", "sentry-sdk", "aioprometheus"]
 client = ["textual", "typer", "pyee", "async-timeout"]
 dev = ["textual-dev"]
 

requirements-server.txt

@@ -1,4 +1,5 @@
 aiohttp==3.9.1 ; python_version >= "3.10" and python_version < "4.0"
+aioprometheus==23.3.0 ; python_version >= "3.10" and python_version < "4.0"
 aiosignal==1.3.1 ; python_version >= "3.10" and python_version < "4.0"
 annotated-types==0.6.0 ; python_version >= "3.10" and python_version < "4.0"
 anyio==4.1.0 ; python_version >= "3.10" and python_version < "4.0"
@@ -30,6 +31,7 @@ itsdangerous==2.1.2 ; python_version >= "3.10" and python_version < "4.0"
 loguru==0.7.2 ; python_version >= "3.10" and python_version < "4.0"
 markupsafe==2.1.3 ; python_version >= "3.10" and python_version < "4.0"
 multidict==6.0.4 ; python_version >= "3.10" and python_version < "4.0"
+orjson==3.9.10 ; python_version >= "3.10" and python_version < "4.0"
 pycparser==2.21 ; python_version >= "3.10" and python_version < "4.0"
 pydantic-core==2.14.5 ; python_version >= "3.10" and python_version < "4.0"
 pydantic-settings==2.1.0 ; python_version >= "3.10" and python_version < "4.0"
@@ -40,6 +42,7 @@ pyopenssl==23.3.0 ; python_version >= "3.10" and python_version < "4.0"
 python-dateutil==2.8.2 ; python_version >= "3.10" and python_version < "4.0"
 python-dotenv==1.0.0 ; python_version >= "3.10" and python_version < "4.0"
 pyyaml==6.0.1 ; python_version >= "3.10" and python_version < "4.0"
+quantile-python==1.1 ; python_version >= "3.10" and python_version < "4.0"
 redis==5.0.1 ; python_version >= "3.10" and python_version < "4.0"
 requests==2.31.0 ; python_version >= "3.10" and python_version < "4.0"
 rodi==2.0.6 ; python_version >= "3.10" and python_version < "4.0"