2018-08-23 00:59:40 +03:00
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// Copyright 2018 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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2018-07-03 14:25:00 +03:00
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2018-09-04 13:59:32 +03:00
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// Package testutil provides helpers to test code using the prometheus package
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// of client_golang.
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//
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// While writing unit tests to verify correct instrumentation of your code, it's
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// a common mistake to mostly test the instrumentation library instead of your
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// own code. Rather than verifying that a prometheus.Counter's value has changed
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// as expected or that it shows up in the exposition after registration, it is
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// in general more robust and more faithful to the concept of unit tests to use
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// mock implementations of the prometheus.Counter and prometheus.Registerer
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// interfaces that simply assert that the Add or Register methods have been
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// called with the expected arguments. However, this might be overkill in simple
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// scenarios. The ToFloat64 function is provided for simple inspection of a
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// single-value metric, but it has to be used with caution.
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//
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// End-to-end tests to verify all or larger parts of the metrics exposition can
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// be implemented with the CollectAndCompare or GatherAndCompare functions. The
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// most appropriate use is not so much testing instrumentation of your code, but
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// testing custom prometheus.Collector implementations and in particular whole
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// exporters, i.e. programs that retrieve telemetry data from a 3rd party source
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// and convert it into Prometheus metrics.
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2020-04-25 00:44:21 +03:00
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//
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// In a similar pattern, CollectAndLint and GatherAndLint can be used to detect
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// metrics that have issues with their name, type, or metadata without being
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// necessarily invalid, e.g. a counter with a name missing the “_total” suffix.
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2018-08-23 00:57:08 +03:00
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package testutil
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2018-07-03 14:25:00 +03:00
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import (
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"bytes"
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"fmt"
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2018-08-23 01:21:38 +03:00
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"io"
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2022-08-05 17:27:47 +03:00
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"net/http"
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2022-04-13 20:38:05 +03:00
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"reflect"
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2018-07-03 14:25:00 +03:00
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2022-04-13 20:38:05 +03:00
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"github.com/davecgh/go-spew/spew"
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2018-08-23 01:05:02 +03:00
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dto "github.com/prometheus/client_model/go"
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2022-08-05 17:27:47 +03:00
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"github.com/prometheus/common/expfmt"
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2018-08-23 01:05:02 +03:00
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2022-08-22 20:37:52 +03:00
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"github.com/prometheus/client_golang/internal/errcapture"
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2018-08-23 01:05:02 +03:00
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"github.com/prometheus/client_golang/prometheus"
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2018-09-03 00:36:34 +03:00
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"github.com/prometheus/client_golang/prometheus/internal"
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2018-07-03 14:25:00 +03:00
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)
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2018-09-04 13:38:29 +03:00
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// ToFloat64 collects all Metrics from the provided Collector. It expects that
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// this results in exactly one Metric being collected, which must be a Gauge,
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// Counter, or Untyped. In all other cases, ToFloat64 panics. ToFloat64 returns
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// the value of the collected Metric.
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//
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// The Collector provided is typically a simple instance of Gauge or Counter, or
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// – less commonly – a GaugeVec or CounterVec with exactly one element. But any
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// Collector fulfilling the prerequisites described above will do.
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//
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// Use this function with caution. It is computationally very expensive and thus
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// not suited at all to read values from Metrics in regular code. This is really
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// only for testing purposes, and even for testing, other approaches are often
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// more appropriate (see this package's documentation).
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//
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// A clear anti-pattern would be to use a metric type from the prometheus
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// package to track values that are also needed for something else than the
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// exposition of Prometheus metrics. For example, you would like to track the
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// number of items in a queue because your code should reject queuing further
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// items if a certain limit is reached. It is tempting to track the number of
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// items in a prometheus.Gauge, as it is then easily available as a metric for
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// exposition, too. However, then you would need to call ToFloat64 in your
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// regular code, potentially quite often. The recommended way is to track the
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// number of items conventionally (in the way you would have done it without
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// considering Prometheus metrics) and then expose the number with a
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// prometheus.GaugeFunc.
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func ToFloat64(c prometheus.Collector) float64 {
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var (
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m prometheus.Metric
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mCount int
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mChan = make(chan prometheus.Metric)
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done = make(chan struct{})
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)
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go func() {
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for m = range mChan {
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mCount++
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}
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close(done)
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}()
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c.Collect(mChan)
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close(mChan)
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<-done
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if mCount != 1 {
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panic(fmt.Errorf("collected %d metrics instead of exactly 1", mCount))
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}
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pb := &dto.Metric{}
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2022-06-17 10:04:06 +03:00
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if err := m.Write(pb); err != nil {
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panic(fmt.Errorf("error happened while collecting metrics: %w", err))
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}
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2018-09-04 13:38:29 +03:00
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if pb.Gauge != nil {
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return pb.Gauge.GetValue()
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}
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if pb.Counter != nil {
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return pb.Counter.GetValue()
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}
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if pb.Untyped != nil {
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return pb.Untyped.GetValue()
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}
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panic(fmt.Errorf("collected a non-gauge/counter/untyped metric: %s", pb))
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}
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2020-05-14 01:17:45 +03:00
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// CollectAndCount registers the provided Collector with a newly created
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// pedantic Registry. It then calls GatherAndCount with that Registry and with
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// the provided metricNames. In the unlikely case that the registration or the
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// gathering fails, this function panics. (This is inconsistent with the other
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// CollectAnd… functions in this package and has historical reasons. Changing
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// the function signature would be a breaking change and will therefore only
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// happen with the next major version bump.)
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func CollectAndCount(c prometheus.Collector, metricNames ...string) int {
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reg := prometheus.NewPedanticRegistry()
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if err := reg.Register(c); err != nil {
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2022-08-03 07:30:51 +03:00
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panic(fmt.Errorf("registering collector failed: %w", err))
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2020-05-14 01:17:45 +03:00
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}
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result, err := GatherAndCount(reg, metricNames...)
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if err != nil {
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panic(err)
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}
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return result
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}
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2020-01-09 13:07:07 +03:00
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2020-05-14 01:17:45 +03:00
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// GatherAndCount gathers all metrics from the provided Gatherer and counts
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// them. It returns the number of metric children in all gathered metric
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// families together. If any metricNames are provided, only metrics with those
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// names are counted.
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func GatherAndCount(g prometheus.Gatherer, metricNames ...string) (int, error) {
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got, err := g.Gather()
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if err != nil {
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2022-08-03 07:30:51 +03:00
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return 0, fmt.Errorf("gathering metrics failed: %w", err)
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2020-05-14 01:17:45 +03:00
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}
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if metricNames != nil {
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got = filterMetrics(got, metricNames)
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}
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2020-01-09 13:07:07 +03:00
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2020-05-14 01:17:45 +03:00
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result := 0
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for _, mf := range got {
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result += len(mf.GetMetric())
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}
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return result, nil
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2020-01-09 13:07:07 +03:00
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}
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2022-08-05 17:27:47 +03:00
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// ScrapeAndCompare calls a remote exporter's endpoint which is expected to return some metrics in
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// plain text format. Then it compares it with the results that the `expected` would return.
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// If the `metricNames` is not empty it would filter the comparison only to the given metric names.
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2022-08-22 20:37:52 +03:00
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func ScrapeAndCompare(url string, expected io.Reader, metricNames ...string) (err error) {
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2022-08-05 17:27:47 +03:00
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resp, err := http.Get(url)
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if err != nil {
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return fmt.Errorf("scraping metrics failed: %w", err)
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}
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2022-08-22 20:37:52 +03:00
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defer errcapture.ExhaustClose(&err, resp.Body, "close response body")
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2022-08-05 17:27:47 +03:00
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if resp.StatusCode != http.StatusOK {
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return fmt.Errorf("the scraping target returned a status code other than 200: %d",
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resp.StatusCode)
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}
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scraped, err := convertReaderToMetricFamily(resp.Body)
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if err != nil {
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return err
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}
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wanted, err := convertReaderToMetricFamily(expected)
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if err != nil {
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return err
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}
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return compareMetricFamilies(scraped, wanted, metricNames...)
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}
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2018-08-23 01:21:38 +03:00
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// CollectAndCompare registers the provided Collector with a newly created
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2020-04-25 16:59:53 +03:00
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// pedantic Registry. It then calls GatherAndCompare with that Registry and with
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// the provided metricNames.
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2018-08-23 01:21:38 +03:00
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func CollectAndCompare(c prometheus.Collector, expected io.Reader, metricNames ...string) error {
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2018-07-03 14:25:00 +03:00
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reg := prometheus.NewPedanticRegistry()
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if err := reg.Register(c); err != nil {
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2022-08-03 07:30:51 +03:00
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return fmt.Errorf("registering collector failed: %w", err)
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2018-07-03 14:25:00 +03:00
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}
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2018-08-23 01:21:38 +03:00
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return GatherAndCompare(reg, expected, metricNames...)
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}
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// GatherAndCompare gathers all metrics from the provided Gatherer and compares
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// it to an expected output read from the provided Reader in the Prometheus text
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// exposition format. If any metricNames are provided, only metrics with those
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// names are compared.
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func GatherAndCompare(g prometheus.Gatherer, expected io.Reader, metricNames ...string) error {
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2022-02-23 14:22:52 +03:00
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return TransactionalGatherAndCompare(prometheus.ToTransactionalGatherer(g), expected, metricNames...)
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}
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// TransactionalGatherAndCompare gathers all metrics from the provided Gatherer and compares
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// it to an expected output read from the provided Reader in the Prometheus text
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// exposition format. If any metricNames are provided, only metrics with those
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// names are compared.
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func TransactionalGatherAndCompare(g prometheus.TransactionalGatherer, expected io.Reader, metricNames ...string) error {
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got, done, err := g.Gather()
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defer done()
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2018-07-03 14:25:00 +03:00
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if err != nil {
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2022-08-03 07:30:51 +03:00
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return fmt.Errorf("gathering metrics failed: %w", err)
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2018-07-03 14:25:00 +03:00
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}
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2022-08-05 17:27:47 +03:00
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wanted, err := convertReaderToMetricFamily(expected)
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if err != nil {
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return err
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2018-07-03 14:25:00 +03:00
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}
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2022-08-05 17:27:47 +03:00
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return compareMetricFamilies(got, wanted, metricNames...)
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}
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// convertReaderToMetricFamily would read from a io.Reader object and convert it to a slice of
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// dto.MetricFamily.
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func convertReaderToMetricFamily(reader io.Reader) ([]*dto.MetricFamily, error) {
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2018-07-03 14:25:00 +03:00
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var tp expfmt.TextParser
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2022-08-05 17:27:47 +03:00
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notNormalized, err := tp.TextToMetricFamilies(reader)
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2018-07-03 14:25:00 +03:00
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if err != nil {
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2022-08-05 17:27:47 +03:00
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return nil, fmt.Errorf("converting reader to metric families failed: %w", err)
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}
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return internal.NormalizeMetricFamilies(notNormalized), nil
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}
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// compareMetricFamilies would compare 2 slices of metric families, and optionally filters both of
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// them to the `metricNames` provided.
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func compareMetricFamilies(got, expected []*dto.MetricFamily, metricNames ...string) error {
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if metricNames != nil {
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got = filterMetrics(got, metricNames)
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2018-07-03 14:25:00 +03:00
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}
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2022-08-05 17:27:47 +03:00
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return compare(got, expected)
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2018-11-13 18:16:43 +03:00
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}
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2018-11-14 14:55:09 +03:00
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// compare encodes both provided slices of metric families into the text format,
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// compares their string message, and returns an error if they do not match.
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2018-11-15 20:40:33 +03:00
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// The error contains the encoded text of both the desired and the actual
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// result.
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2018-11-14 14:55:09 +03:00
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func compare(got, want []*dto.MetricFamily) error {
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2018-11-13 18:16:43 +03:00
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var gotBuf, wantBuf bytes.Buffer
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enc := expfmt.NewEncoder(&gotBuf, expfmt.FmtText)
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for _, mf := range got {
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if err := enc.Encode(mf); err != nil {
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2022-08-03 07:30:51 +03:00
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return fmt.Errorf("encoding gathered metrics failed: %w", err)
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2018-11-13 18:16:43 +03:00
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}
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}
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enc = expfmt.NewEncoder(&wantBuf, expfmt.FmtText)
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for _, mf := range want {
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if err := enc.Encode(mf); err != nil {
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2022-08-03 07:30:51 +03:00
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return fmt.Errorf("encoding expected metrics failed: %w", err)
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2018-07-03 14:25:00 +03:00
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}
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2018-11-13 18:16:43 +03:00
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}
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2022-04-13 20:38:05 +03:00
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if diffErr := diff(wantBuf, gotBuf); diffErr != "" {
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return fmt.Errorf(diffErr)
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}
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return nil
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}
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2018-07-03 14:25:00 +03:00
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2022-04-13 20:38:05 +03:00
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// diff returns a diff of both values as long as both are of the same type and
|
|
|
|
|
// are a struct, map, slice, array or string. Otherwise it returns an empty string.
|
2022-06-17 10:04:06 +03:00
|
|
|
|
func diff(expected, actual interface{}) string {
|
2022-04-13 20:38:05 +03:00
|
|
|
|
if expected == nil || actual == nil {
|
|
|
|
|
return ""
|
|
|
|
|
}
|
2018-07-03 14:25:00 +03:00
|
|
|
|
|
2022-04-13 20:38:05 +03:00
|
|
|
|
et, ek := typeAndKind(expected)
|
|
|
|
|
at, _ := typeAndKind(actual)
|
|
|
|
|
if et != at {
|
|
|
|
|
return ""
|
|
|
|
|
}
|
2018-07-03 14:25:00 +03:00
|
|
|
|
|
2022-04-13 20:38:05 +03:00
|
|
|
|
if ek != reflect.Struct && ek != reflect.Map && ek != reflect.Slice && ek != reflect.Array && ek != reflect.String {
|
|
|
|
|
return ""
|
|
|
|
|
}
|
2018-11-14 14:55:09 +03:00
|
|
|
|
|
2022-04-13 20:38:05 +03:00
|
|
|
|
var e, a string
|
|
|
|
|
c := spew.ConfigState{
|
|
|
|
|
Indent: " ",
|
|
|
|
|
DisablePointerAddresses: true,
|
|
|
|
|
DisableCapacities: true,
|
|
|
|
|
SortKeys: true,
|
2018-11-14 14:55:09 +03:00
|
|
|
|
}
|
2022-04-13 20:38:05 +03:00
|
|
|
|
if et != reflect.TypeOf("") {
|
|
|
|
|
e = c.Sdump(expected)
|
|
|
|
|
a = c.Sdump(actual)
|
|
|
|
|
} else {
|
|
|
|
|
e = reflect.ValueOf(expected).String()
|
|
|
|
|
a = reflect.ValueOf(actual).String()
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
diff, _ := internal.GetUnifiedDiffString(internal.UnifiedDiff{
|
|
|
|
|
A: internal.SplitLines(e),
|
|
|
|
|
B: internal.SplitLines(a),
|
|
|
|
|
FromFile: "metric output does not match expectation; want",
|
|
|
|
|
FromDate: "",
|
|
|
|
|
ToFile: "got:",
|
|
|
|
|
ToDate: "",
|
|
|
|
|
Context: 1,
|
|
|
|
|
})
|
|
|
|
|
|
|
|
|
|
if diff == "" {
|
|
|
|
|
return ""
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return "\n\nDiff:\n" + diff
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
// typeAndKind returns the type and kind of the given interface{}
|
|
|
|
|
func typeAndKind(v interface{}) (reflect.Type, reflect.Kind) {
|
|
|
|
|
t := reflect.TypeOf(v)
|
|
|
|
|
k := t.Kind()
|
|
|
|
|
|
|
|
|
|
if k == reflect.Ptr {
|
|
|
|
|
t = t.Elem()
|
|
|
|
|
k = t.Kind()
|
|
|
|
|
}
|
|
|
|
|
return t, k
|
2018-07-03 14:25:00 +03:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
func filterMetrics(metrics []*dto.MetricFamily, names []string) []*dto.MetricFamily {
|
|
|
|
|
var filtered []*dto.MetricFamily
|
|
|
|
|
for _, m := range metrics {
|
|
|
|
|
for _, name := range names {
|
|
|
|
|
if m.GetName() == name {
|
2018-08-23 01:21:38 +03:00
|
|
|
|
filtered = append(filtered, m)
|
2018-07-03 14:25:00 +03:00
|
|
|
|
break
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
return filtered
|
|
|
|
|
}
|