Add metrics for request/task counting

src/pretix/base/metrics.py

@@ -146,5 +146,7 @@ def metric_values():
 """
 Provided metrics
 """
-http_requests_total = Counter("http_requests_total", "Total number of HTTP requests made.", ["code", "handler", "method"])
+http_view_requests = Counter("http_view_requests", "Total number of HTTP requests made.",
-# usage: http_requests_total.inc(code="200", handler="/foo", method="GET")
+                             ["status_code", "method", "url_name"])
+celery_task_runs = Counter("celery_task_runs", "Total calls to a celery task",
+                           ["task_name", "status"])

src/pretix/base/services/async.py

@@ -15,12 +15,12 @@ import time
 from django.conf import settings
 from django.db import transaction
 
+from pretix.base.metrics import celery_task_runs
 from pretix.celery_app import app
 
 
 class ProfiledTask(app.Task):
     def __call__(self, *args, **kwargs):
-
         if settings.PROFILING_RATE > 0 and random.random() < settings.PROFILING_RATE / 100:
             profiler = cProfile.Profile()
             profiler.enable()
@@ -35,6 +35,23 @@ class ProfiledTask(app.Task):
         else:
             return super().__call__(*args, **kwargs)
 
+    def on_failure(self, exc, task_id, args, kwargs, einfo):
+        if settings.METRICS_ENABLED:
+            expected = False
+            for t in self.throws:
+                if isinstance(exc, t):
+                    expected = True
+                    break
+            celery_task_runs.inc(1, task_name=self.name, status="expected-error" if expected else "error")
+
+        return super().on_failure(exc, task_id, args, kwargs, einfo)
+
+    def on_success(self, retval, task_id, args, kwargs):
+        if settings.METRICS_ENABLED:
+            celery_task_runs.inc(1, task_name=self.name, status="success")
+
+        return super().on_success(retval, task_id, args, kwargs)
+
 
 class TransactionAwareTask(ProfiledTask):
     """

src/pretix/helpers/metrics/middleware.py

@@ -0,0 +1,30 @@
+from django.urls import resolve
+
+from pretix.base.metrics import http_view_requests
+
+
+class MetricsMiddleware(object):
+    blacklist = (
+        '/healthcheck/',
+        '/jsi18n/',
+        '/metrics',
+    )
+
+    def __init__(self, get_response):
+        self.get_response = get_response
+        # One-time configuration and initialization.
+
+    def __call__(self, request):
+        # Code to be executed for each request before
+        # the view (and later middleware) are called.
+        for b in self.blacklist:
+            if b in request.path:
+                return self.get_response(request)
+
+        url = resolve(request.path_info)
+
+        resp = self.get_response(request)
+        http_view_requests.inc(1, status_code=resp.status_code, method=request.method,
+                               url_name=url.namespace + ':' + url.url_name)
+
+        return resp

src/pretix/settings.py

@@ -261,6 +261,11 @@ except ImportError:
     pass
 
 
+if METRICS_ENABLED:
+    MIDDLEWARE.insert(MIDDLEWARE.index('pretix.multidomain.middlewares.MultiDomainMiddleware') + 1,
+                      'pretix.helpers.metrics.middleware.MetricsMiddleware')
+
+
 PROFILING_RATE = config.getfloat('django', 'profile', fallback=0)  # Percentage of requests to profile
 if PROFILING_RATE > 0:
     if not os.path.exists(PROFILE_DIR):