Update FastAPI 0.87.0 → 0.95.1

dearmep/main.py

@@ -1,8 +1,11 @@
 import logging
 from typing import Optional
+
 from fastapi import FastAPI
-from prometheus_fastapi_instrumentator import Instrumentator
 from pydantic import ValidationError
+from starlette_exporter import PrometheusMiddleware, handle_metrics
+from starlette_exporter.optional_metrics import request_body_size, \
+    response_body_size
 from yaml.parser import ParserError
 
 from . import __version__, static_files
@@ -49,13 +52,15 @@ def create_app(config_dict: Optional[dict] = None) -> FastAPI:
         version=__version__,
     )
 
-    @app.on_event("startup")
-    def prometheus_instrument():
-        Instrumentator(
-            should_group_status_codes=False,
-        ).instrument(app).expose(app)
-
     app.include_router(api_v1.router, prefix="/api/v1")
     static_files.mount_if_configured(app, "/static")
 
+    app.add_middleware(
+        PrometheusMiddleware,
+        app_name=APP_NAME,
+        group_paths=True,
+        optional_metrics=[request_body_size, response_body_size],
+    )
+    app.add_route("/metrics", handle_metrics)
+
     return app

pyproject.toml

@@ -12,8 +12,7 @@ dearmep = "dearmep.cli:run"
 
 [tool.poetry.dependencies]
 python = "^3.8"
-fastapi = "^0.87"
-prometheus-fastapi-instrumentator = "^5.9.1"
+fastapi = "^0.95.1"
 PyYAML = "^6.0"
 limits = "^3.3.1"
 lzip = "^1.2.0"
@@ -23,6 +22,7 @@ defusedxml = "^0.7.1"
 httpx = ">=0.23"
 uvicorn = {extras = ["standard"], version = "^0.21.1"}
 python-geoacumen = ">=2023"
+starlette-exporter = "^0.15.1"
 
 [tool.poetry.group.dev.dependencies]
 flake8 = "^4.0.1"

tests/test_metrics.py

@@ -4,36 +4,19 @@
 from fastapi.testclient import TestClient
 import pytest
 
-from conftest import fastapi_app_func, fastapi_factory_func
+from dearmep.config import APP_NAME
 
 
-# If we initialize the Prometheus instrumentator more than once, it will create
-# duplicate timeseries, which is not allowed. Therefore, we only get to call
-# this once.
-@pytest.fixture(scope="session")
-def prom_client():
-    # We can't simply use the fastapi_app fixture because its scope is
-    # per-function, not per-session.
-    with fastapi_factory_func() as start:
-        with fastapi_app_func(start) as app:
-            client = TestClient(app)
-
-    with client as client_with_events:
-        # The `with` causes `@app.on_event("startup")` code to run.
-        # <https://fastapi.tiangolo.com/advanced/testing-events/>
-        yield client_with_events
-
-
-def metrics_lines_func(prom_client: TestClient) -> Iterable[str]:
-    res = prom_client.get("/metrics")
+def metrics_lines_func(client: TestClient) -> Iterable[str]:
+    res = client.get("/metrics")
     assert res.status_code == status.HTTP_200_OK
     for line in res.iter_lines():
         yield str(line).rstrip("\r\n")
 
 
 @pytest.fixture
-def metrics_lines(prom_client: TestClient):
-    yield list(metrics_lines_func(prom_client))
+def metrics_lines(client: TestClient):
+    yield list(metrics_lines_func(client))
 
 
 def test_python_info_in_metrics(metrics_lines: Iterable[str]):
@@ -45,14 +28,15 @@ def test_python_info_in_metrics(metrics_lines: Iterable[str]):
     ]
 
 
-def test_non_grouped_status_codes(prom_client: TestClient):
+def test_non_grouped_status_codes(client: TestClient):
     # Do a throwaway request in order to have at least one request in the
     # metrics when doing the actual test.
-    assert prom_client.get("/metrics").status_code == status.HTTP_200_OK
+    assert client.get("/metrics").status_code == status.HTTP_200_OK
 
-    mark = 'http_requests_total{handler="/metrics",method="GET",status="200"} '
+    mark = f'starlette_requests_total{{app_name="{APP_NAME}",method="GET",' \
+        + 'path="/metrics",status_code="200"} '
     assert [
         line
-        for line in metrics_lines_func(prom_client)
+        for line in metrics_lines_func(client)
         if line.startswith(mark)
     ]