Merge pull request openlabs#12 from Traum-Ferienwohnungen/limit_possible_metric_labels

Create metrics only for specific endpoints to not flood prometheus

Author: madnight

src/app.py

@@ -17,7 +17,7 @@
 from prometheus import prometheus_metrics
 
 @Request.application
-@prometheus_metrics('/metrics')
+@prometheus_metrics('/metrics', ('/', '/healthz'))
 def application(request):
 
     if request.method == 'GET':

src/prometheus.py

@@ -14,12 +14,17 @@
     ['method', 'endpoint', 'code']
 )
 
-def prometheus_metrics(metrics_path):
+def prometheus_metrics(metrics_path, monitor_endpoints):
+    monitor_endpoints = set([metrics_path] + list(monitor_endpoints))
     def prometheus_metrics_decorator(f):
         @wraps(f)
         def f_wrapper(request):
-            start_time = time()
+            # Create metrics only for specific endpoints to not flood
+            # prometheus with dynamically created labels.
+            if request.path not in monitor_endpoints:
+                return f(request)
 
+            start_time = time()
             if request.method == 'GET' and request.path == metrics_path:
                 status = 200
                 REQUEST_LATENCIES.labels(