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5836b3d8c1
This is causing problems with certain servers that have a lot of open FDs; the process collector that Prometheus provides generates a lot of garbage when enumerating open FDs, which is why we have metrics.CurrentFDs (which uses util/dirwalk). Updates tailscale/corp#19900 Signed-off-by: Andrew Dunham <andrew@du.nham.ca> Change-Id: I732f854e637c4d7a651b3c74cd8e363cb1092bcc
105 lines
2.7 KiB
Go
105 lines
2.7 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package promvarz
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import (
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"expvar"
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"net/http"
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"net/http/httptest"
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"runtime"
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"strings"
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"testing"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promauto"
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"github.com/prometheus/client_golang/prometheus/testutil"
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"github.com/prometheus/common/expfmt"
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"tailscale.com/tstest"
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)
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var (
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testVar1 = expvar.NewInt("gauge_promvarz_test_expvar")
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testVar2 = promauto.NewGauge(prometheus.GaugeOpts{Name: "promvarz_test_native"})
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)
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func TestHandler(t *testing.T) {
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testVar1.Set(42)
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testVar2.Set(4242)
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svr := httptest.NewServer(http.HandlerFunc(Handler))
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defer svr.Close()
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want := `
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# TYPE promvarz_test_expvar gauge
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promvarz_test_expvar 42
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# TYPE promvarz_test_native gauge
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promvarz_test_native 4242
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`
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if err := testutil.ScrapeAndCompare(svr.URL, strings.NewReader(want), "promvarz_test_expvar", "promvarz_test_native"); err != nil {
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t.Error(err)
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}
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// By default, we include Prometheus's process metrics; these are only
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// published on Linux, so check that they're present.
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//
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// If we ever change this behaviour, feel free to change or remove this
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// test; it's only here so that the TestOmitPromethusMetrics test can
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// check that it's working.
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if runtime.GOOS == "linux" && !hasProcessMetrics(t, svr.URL) {
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t.Error("process metrics not found")
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}
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}
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// TestOmitPromethusMetrics verifies that OmitPromethusMetrics works correctly.
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func TestOmitPromethusMetrics(t *testing.T) {
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if runtime.GOOS != "linux" {
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t.Skip("process metrics are only published on Linux")
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}
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tstest.Replace(t, &OmitPromethusMetrics, true)
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testVar1.Set(42)
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svr := httptest.NewServer(http.HandlerFunc(Handler))
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defer svr.Close()
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want := `
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# TYPE promvarz_test_expvar gauge
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promvarz_test_expvar 42
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`
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if err := testutil.ScrapeAndCompare(svr.URL, strings.NewReader(want), "promvarz_test_expvar"); err != nil {
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t.Error(err)
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}
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if hasProcessMetrics(t, svr.URL) {
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t.Error("process metrics unexpectedly found")
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}
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}
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// hasProcessMetrics checks if metrics from the Prometheus process collector
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// are present at the given metrics URL.
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func hasProcessMetrics(tb testing.TB, url string) bool {
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resp, err := http.Get(url)
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if err != nil {
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tb.Errorf("scraping metrics failed: %v", err)
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return false
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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tb.Errorf("the scraping target returned a status code other than 200: %d",
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resp.StatusCode)
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return false
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}
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var tp expfmt.TextParser
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metrics, err := tp.TextToMetricFamilies(resp.Body)
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if err != nil {
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tb.Errorf("converting body to metric families failed: %v", err)
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return false
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}
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if _, found := metrics["process_open_fds"]; found {
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return true
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}
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return false
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}
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