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synced 2026-08-14 11:26:26 +00:00
Add basic instrumentation possibilities to pretix (#271)
* add basic instrumentation possibilities to pretix * make tabs to spaces * apply flake8 * implement upstreams suggestions, round 1 * adjust naming of redis-connection * address noredis * add view for metrics * implement HTTP basic auth in front of metrics-endpoint * rename labelset * make flake8-clean * implement upstreams suggestions, round 2 * correct minor slipups * fix missing return * let isort add an empty line * implement test for counter * implement upstream suggestions, round 3 * correct typo * implement first test for view * finish view-test * fix deprecated keyword * implement upstream-suggestions, round 4 * implement test for gauge * test exceptions as well * add db-decorator
This commit is contained in:
Jonas Große Sundrup
committed by
Raphael Michel
Raphael Michel
parent
d308821c4c
commit
d3327b1e45
@@ -174,6 +174,20 @@ Example::
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.. WARNING:: Never set this to ``True`` in production!
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Metrics
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-------
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If you want to fetch internally collected prometheus-style metrics you need to configure the credentials for the
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metrics endpoint and enable it::
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[metrics]
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enabled=true
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user=your_user
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passphrase=mysupersecretpassphrase
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Currently, metrics-collection requires a redis server to be available.
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Memcached
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---------
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Executable
+150
@@ -0,0 +1,150 @@
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from django.conf import settings
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if settings.HAS_REDIS:
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import django_redis
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redis = django_redis.get_redis_connection("redis")
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REDIS_KEY_PREFIX = "pretix_metrics_"
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class Metric(object):
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"""
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Base Metrics Object
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"""
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def __init__(self, name, helpstring, labelnames=None):
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self.name = name
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self.helpstring = helpstring
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self.labelnames = labelnames or []
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def __repr__(self):
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return self.name + "{" + ",".join(self.labelnames) + "}"
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def _check_label_consistency(self, labels):
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"""
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Checks if the given labels provides exactly the labels that are required.
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"""
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# test if every required label is provided
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for labelname in self.labelnames:
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if labelname not in labels:
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raise ValueError("Label {0} not specified.".format(labelname))
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# now test if no further labels are required
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if len(labels) != len(self.labelnames):
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raise ValueError("Unknown labels used: {}".format(", ".join(set(labels) - set(self.labelnames))))
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def _construct_metric_identifier(self, metricname, labels=None):
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"""
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Constructs the scrapable metricname usable in the output format.
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"""
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if not labels:
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return metricname
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else:
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named_labels = []
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for labelname in self.labelnames:
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named_labels.append('{}="{}",'.format(labelname, labels[labelname]))
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return metricname + "{" + ",".join(named_labels) + "}"
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def _inc_in_redis(self, key, amount):
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"""
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Increments given key in Redis.
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"""
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rkey = REDIS_KEY_PREFIX + key
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if settings.HAS_REDIS:
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redis.incrbyfloat(rkey, amount)
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def _set_in_redis(self, key, value):
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"""
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Sets given key in Redis.
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"""
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rkey = REDIS_KEY_PREFIX + key
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if settings.HAS_REDIS:
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redis.set(rkey, value)
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class Counter(Metric):
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"""
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Counter Metric Object
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Counters can only be increased, they can neither be set to a specific value
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nor decreased.
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"""
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def inc(self, amount=1, **kwargs):
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"""
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Increments Counter by given amount for the labels specified in kwargs.
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"""
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if amount < 0:
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raise ValueError("Counter cannot be increased by negative values.")
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self._check_label_consistency(kwargs)
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fullmetric = self._construct_metric_identifier(self.name, kwargs)
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self._inc_in_redis(fullmetric, amount)
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class Gauge(Metric):
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"""
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Gauge Metric Object
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Gauges can be set to a specific value, increased and decreased.
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"""
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def set(self, value=1, **kwargs):
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"""
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Sets Gauge to a specific value for the labels specified in kwargs.
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"""
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self._check_label_consistency(kwargs)
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fullmetric = self._construct_metric_identifier(self.name, kwargs)
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self._set_in_redis(fullmetric, value)
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def inc(self, amount=1, **kwargs):
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"""
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Increments Gauge by given amount for the labels specified in kwargs.
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"""
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if amount < 0:
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raise ValueError("Amount must be greater than zero. Otherwise use dec().")
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self._check_label_consistency(kwargs)
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fullmetric = self._construct_metric_identifier(self.name, kwargs)
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self._inc_in_redis(fullmetric, amount)
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def dec(self, amount=1, **kwargs):
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"""
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Decrements Gauge by given amount for the labels specified in kwargs.
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"""
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if amount < 0:
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raise ValueError("Amount must be greater than zero. Otherwise use inc().")
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self._check_label_consistency(kwargs)
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fullmetric = self._construct_metric_identifier(self.name, kwargs)
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self._inc_in_redis(fullmetric, amount * -1)
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def metric_values():
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"""
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Produces the scrapable textformat to be presented to the monitoring system
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"""
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if not settings.HAS_REDIS:
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return ""
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metrics = {}
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for key in redis.scan_iter(match=REDIS_KEY_PREFIX + "*"):
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dkey = key.decode("utf-8")
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_, _, output_key = dkey.split("_", 2)
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value = float(redis.get(dkey).decode("utf-8"))
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metrics[output_key] = value
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return metrics
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"""
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Provided metrics
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"""
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http_requests_total = Counter("http_requests_total", "Total number of HTTP requests made.", ["code", "handler", "method"])
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# usage: http_requests_total.inc(code="200", handler="/foo", method="GET")
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@@ -0,0 +1,43 @@
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from django.conf import settings
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from django.http import HttpResponse
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from .. import metrics
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def unauthed_response():
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content = "<html><title>Forbidden</title><body>You are not authorized to view this page.</body></html>"
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response = HttpResponse(content, content_type="text/html")
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response["WWW-Authenticate"] = 'Basic realm="metrics"'
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response.status_code = 401
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return response
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def serve_metrics(request):
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if not settings.METRICS_ENABLED:
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return unauthed_response()
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# check if the user is properly authorized:
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if "HTTP_AUTHORIZATION" not in request.META:
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return unauthed_response()
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method, credentials = request.META["HTTP_AUTHORIZATION"].split(" ", 1)
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if method.lower() != "basic":
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return unauthed_response()
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user, passphrase = credentials.strip().decode("base64").split(":", 1)
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if user != settings.METRICS_USER:
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return unauthed_response()
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if passphrase != settings.METRICS_PASSPHRASE:
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return unauthed_response()
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# ok, the request passed the authentication-barrier, let's hand out the metrics:
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m = metrics.metric_values()
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output = []
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for metric, value in m:
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output.append("{} {}".format(metric, str(value)))
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content = "\n".join(output)
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return HttpResponse(content)
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@@ -90,6 +90,10 @@ EMAIL_SUBJECT_PREFIX = '[pretix] '
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ADMINS = [('Admin', n) for n in config.get('mail', 'admins', fallback='').split(",") if n]
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METRICS_ENABLED = config.get('metrics', 'enabled', fallback=False)
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METRICS_USER = config.get('metrics', 'user', fallback="metrics")
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METRICS_PASSPHRASE = config.get('metrics', 'passphrase', fallback="")
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CACHES = {
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'default': {
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'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
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+3
-1
@@ -4,7 +4,7 @@ from django.conf.urls import include, url
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import pretix.control.urls
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import pretix.presale.urls
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from .base.views import cachedfiles, health, js_catalog, redirect
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from .base.views import cachedfiles, health, js_catalog, metrics, redirect
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base_patterns = [
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url(r'^download/(?P<id>[^/]+)/$', cachedfiles.DownloadView.as_view(),
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@@ -13,6 +13,8 @@ base_patterns = [
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name='healthcheck'),
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url(r'^redirect/$', redirect.redir_view, name='redirect'),
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url(r'^jsi18n/(?P<lang>[a-zA-Z-_]+)/$', js_catalog.js_catalog, name='javascript-catalog'),
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url(r'^metrics$', metrics.serve_metrics,
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name='metrics'),
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]
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control_patterns = [
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@@ -0,0 +1,140 @@
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# pytest
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import base64
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import pytest
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from django.test import override_settings
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from pretix.base import metrics
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from pretix.base.views import metrics as metricsview
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class FakeRedis(object):
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def __init__(self):
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self.storage = {}
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def incrbyfloat(self, rkey, amount):
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if rkey in self.storage:
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self.storage[rkey] += amount
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else:
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self.set(rkey, amount)
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def set(self, rkey, value):
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self.storage[rkey] = value
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def get(self, rkey):
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# bytes-conversion here for emulating redis behavior without making incr too hard
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return bytes(self.storage[rkey], encoding='utf-8')
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@override_settings(HAS_REDIS=True)
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def test_counter(monkeypatch):
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fake_redis = FakeRedis()
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monkeypatch.setattr(metrics, "redis", fake_redis, raising=False)
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# now test
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fullname_GET = metrics.http_requests_total._construct_metric_identifier('http_requests_total', {"code": "200", "handler": "/foo", "method": "GET"})
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fullname_POST = metrics.http_requests_total._construct_metric_identifier('http_requests_total', {"code": "200", "handler": "/foo", "method": "POST"})
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metrics.http_requests_total.inc(code="200", handler="/foo", method="GET")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_GET] == 1
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metrics.http_requests_total.inc(code="200", handler="/foo", method="GET")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_GET] == 2
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metrics.http_requests_total.inc(7, code="200", handler="/foo", method="GET")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_GET] == 9
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metrics.http_requests_total.inc(7, code="200", handler="/foo", method="POST")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_GET] == 9
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_POST] == 7
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with pytest.raises(ValueError):
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metrics.http_requests_total.inc(-4, code="200", handler="/foo", method="POST")
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with pytest.raises(ValueError):
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metrics.http_requests_total.inc(-4, code="200", handler="/foo", method="POST", too="much")
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# test dimensionless counters
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dimless_counter = metrics.Counter("dimless_counter", "this is a helpstring")
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fullname_dimless = dimless_counter._construct_metric_identifier('dimless_counter')
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dimless_counter.inc(20)
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_dimless] == 20
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@override_settings(HAS_REDIS=True)
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def test_gauge(monkeypatch):
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fake_redis = FakeRedis()
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monkeypatch.setattr(metrics, "redis", fake_redis, raising=False)
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test_gauge = metrics.Gauge("my_gauge", "this is a helpstring", ["dimension"])
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# now test
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fullname_one = test_gauge._construct_metric_identifier('my_gauge', {"dimension": "one"})
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fullname_two = test_gauge._construct_metric_identifier('my_gauge', {"dimension": "two"})
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fullname_three = test_gauge._construct_metric_identifier('my_gauge', {"dimension": "three"})
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test_gauge.inc(dimension="one")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 1
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test_gauge.inc(7, dimension="one")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 8
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test_gauge.dec(2, dimension="one")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 6
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test_gauge.set(3, dimension="two")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 6
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_two] == 3
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test_gauge.set(4, dimension="two")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 6
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_two] == 4
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test_gauge.dec(7, dimension="three")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 6
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_two] == 4
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_three] == -7
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test_gauge.inc(14, dimension="three")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 6
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_two] == 4
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_three] == 7
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test_gauge.set(17, dimension="three")
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_one] == 6
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_two] == 4
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_three] == 17
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with pytest.raises(ValueError):
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test_gauge.inc(-17, dimension="three")
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with pytest.raises(ValueError):
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test_gauge.dec(-17, dimension="three")
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with pytest.raises(ValueError):
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test_gauge.set(7, unknown_label="foo")
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with pytest.raises(ValueError):
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test_gauge.set(7, dimension="one", too="much")
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# test dimensionless gauges
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dimless_gauge = metrics.Gauge("dimless_gauge", "this is a helpstring")
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fullname_dimless = dimless_gauge._construct_metric_identifier('dimless_gauge')
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dimless_gauge.set(20)
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assert fake_redis.storage[metrics.REDIS_KEY_PREFIX + fullname_dimless] == 20
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@pytest.mark.django_db
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@override_settings(HAS_REDIS=True, METRICS_USER="foo", METRICS_PASSPHRASE="bar")
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def test_metrics_view(monkeypatch, client):
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fake_redis = FakeRedis()
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monkeypatch.setattr(metricsview.metrics, "redis", fake_redis, raising=False)
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counter_value = 3
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fullname = metrics.http_requests_total._construct_metric_identifier('http_requests_total', {"code": "200", "handler": "/foo", "method": "GET"})
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metricsview.metrics.http_requests_total.inc(counter_value, code="200", handler="/foo", method="GET")
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# test unauthorized-page
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assert "You are not authorized" in metricsview.serve_metrics(None).content.decode('utf-8')
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assert "You are not authorized" in client.get('/metrics').content.decode('utf-8')
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assert "{} {}".format(fullname, counter_value) not in client.get('/metrics')
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# test metrics-view
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basic_auth = {"HTTP_AUTHORIZATION": base64.b64encode(bytes("foo:bar", "utf-8"))}
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assert "{} {}".format(fullname, counter_value) not in client.get("/metrics", headers=basic_auth)
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