70 lines
2.6 KiB
Go
70 lines
2.6 KiB
Go
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// Copyright 2014 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package prometheus_test
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import (
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"net/http"
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"github.com/prometheus/client_golang/prometheus"
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)
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var (
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// apiRequestDuration tracks the duration separate for each HTTP status
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// class (1xx, 2xx, ...). This creates a fair amount of time series on
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// the Prometheus server. Usually, you would track the duration of
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// serving HTTP request without partitioning by outcome. Do something
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// like this only if needed. Also note how only status classes are
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// tracked, not every single status code. The latter would create an
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// even larger amount of time series. Request counters partitioned by
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// status code are usually OK as each counter only creates one time
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// series. Histograms are way more expensive, so partition with care and
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// only where you really need separate latency tracking.
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apiRequestDuration = prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Name: "api_request_duration_seconds",
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Help: "Histogram for the request duration of the public API, partitioned by status class.",
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Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
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},
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[]string{"status_class"},
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)
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)
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func handler(w http.ResponseWriter, r *http.Request) {
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status := http.StatusOK
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// The ObserverFunc gets called by the deferred ObserveDuration and
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// decides wich Histogram's Observe method is called.
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timer := prometheus.NewTimer(prometheus.ObserverFunc(func(v float64) {
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switch {
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case status >= http.StatusInternalServerError:
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apiRequestDuration.WithLabelValues("5xx").Observe(v)
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case status >= http.StatusBadRequest:
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apiRequestDuration.WithLabelValues("4xx").Observe(v)
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case status >= http.StatusMultipleChoices:
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apiRequestDuration.WithLabelValues("3xx").Observe(v)
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case status >= http.StatusOK:
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apiRequestDuration.WithLabelValues("2xx").Observe(v)
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default:
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apiRequestDuration.WithLabelValues("1xx").Observe(v)
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}
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}))
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defer timer.ObserveDuration()
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// Handle the request. Set status accordingly.
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// ...
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}
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func ExampleTimer_complex() {
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http.HandleFunc("/api", handler)
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}
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