Add Prometheus metrics

Makefile

@@ -14,4 +14,4 @@ serve-uwsgi:
 	SIMPLE_WEBFINGER_CONFIG_FILE="examples/example-config.yaml" python3 -m poetry run uwsgi -w "simple_webfinger.app:create_app()" --master --http 0.0.0.0:8000
 
 serve:
-	SIMPLE_WEBFINGER_CONFIG_FILE="examples/example-config.yaml" FLASK_DEBUG=1 FLASK_APP="simple_webfinger.app:create_app()" python3 -m poetry run flask run 
+	DEBUG_METRICS=1 SIMPLE_WEBFINGER_CONFIG_FILE="examples/example-config.yaml" FLASK_DEBUG=1 FLASK_APP="simple_webfinger.app:create_app()" python3 -m poetry run flask run 

poetry.lock

@@ -203,6 +203,35 @@ files = [
 dev = ["pre-commit", "tox"]
 testing = ["pytest", "pytest-benchmark"]
 
+[[package]]
+name = "prometheus-client"
+version = "0.20.0"
+description = "Python client for the Prometheus monitoring system."
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "prometheus_client-0.20.0-py3-none-any.whl", hash = "sha256:cde524a85bce83ca359cc837f28b8c0db5cac7aa653a588fd7e84ba061c329e7"},
+    {file = "prometheus_client-0.20.0.tar.gz", hash = "sha256:287629d00b147a32dcb2be0b9df905da599b2d82f80377083ec8463309a4bb89"},
+]
+
+[package.extras]
+twisted = ["twisted"]
+
+[[package]]
+name = "prometheus-flask-exporter"
+version = "0.23.1"
+description = "Prometheus metrics exporter for Flask"
+optional = false
+python-versions = "*"
+files = [
+    {file = "prometheus_flask_exporter-0.23.1-py3-none-any.whl", hash = "sha256:ab49b2c40b57cd35cd51e91e59b3c306b3754477095c4f3cf679034c5122398c"},
+    {file = "prometheus_flask_exporter-0.23.1.tar.gz", hash = "sha256:587c770a1061e93d72c5cbcdefbd7b633fb764e39dffd7dd16932c9124559244"},
+]
+
+[package.dependencies]
+flask = "*"
+prometheus-client = "*"
+
 [[package]]
 name = "pydantic"
 version = "2.8.2"
@@ -526,4 +555,4 @@ watchdog = ["watchdog (>=2.3)"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.11"
-content-hash = "b042304154f4d2a7ccbe9fffcebc6db3c38549d73e080d317b7d039c33a28fa3"
+content-hash = "b221de707ffd32f063004ac38e899c2065608fbd7717d0e8885e42fb554e4b14"

pyproject.toml

@@ -12,6 +12,7 @@ Flask = "^3.0.3"
 PyYAML = "^6.0.2"
 uwsgi = "^2.0.26"
 pydantic = "^2.8.2"
+prometheus-flask-exporter = "^0.23.1"
 
 [tool.poetry.group.dev.dependencies]
 pytest = "^8.0.0"

simple_webfinger/app.py

@@ -2,6 +2,8 @@ from urllib.parse import urlparse
 
 import yaml
 from flask import Flask, abort, request
+from prometheus_flask_exporter import PrometheusMetrics
+
 from simple_webfinger.models.webfinger import JSONResourceDefinition
 
 
@@ -62,6 +64,10 @@ def filter_links(links: dict[str, str], rel: list[str]) -> list:
 
 def create_app(config={}):
     app = Flask("simple_webfinger")
+
+    metrics = PrometheusMetrics(app)
+    metrics.info('app_info', 'Application info', version='0.1.0')
+    
     app.webfinger_config = {
         "domain": None,
         "accounts": {},