feat: add optional Prometheus metrics endpoint

config.py.example

@@ -52,3 +52,7 @@
 #LOGIN_USERNAME_LABEL = "Username"
 #LOGIN_PASSWORD_LABEL = "Password"
 #LOGIN_SUBMIT_LABEL = "Sign in"
+
+### Metrics (optional)
+# Enable Prometheus metrics endpoint at /metrics
+#ENABLE_METRICS_ENDPOINT=True

lufa/__init__.py

@@ -115,6 +115,13 @@ def set_security_headers(response):
     csrf.exempt(api_v1.bp)
     app.register_blueprint(frontend.bp)
 
+    # Prometheus metrics
+    if app.config.get("ENABLE_METRICS_ENDPOINT", False):
+        from prometheus_flask_exporter import PrometheusMetrics
+
+        PrometheusMetrics(app, prefix="lufa")
+        app.logger.info("Prometheus metrics enabled at /metrics")
+
     login_manager = LoginManager(app)
     if str(app.config.get("AUTH")).upper().startswith("LOCAL"):
         user_manager = UserManager(app)

requirements.txt

@@ -1,6 +1,7 @@
 Flask==3.1.3
 flask-ldap3-login==1.0.2
 Flask-Login==0.6.3
+prometheus-flask-exporter==0.23.2
 psycopg2-binary==2.9.11
 uWSGI==2.0.31
 requests==2.32.5