mirror of https://github.com/tailscale/tailscale/
usermetric: add initial user-facing metrics
This commit adds a new usermetric package and wires up metrics across the tailscale client. Updates tailscale/corp#22075 Co-authored-by: Anton Tolchanov <anton@tailscale.com> Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>jwhited/test-local-forwarder
Kristoffer Dalby
4 months ago
committed by
Kristoffer Dalby
parent
06c31f4e91
commit
a2c42d3cd4
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package usermetric provides a container and handler
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// for user-facing metrics.
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package usermetric
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import (
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"expvar"
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"fmt"
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"io"
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"net/http"
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"tailscale.com/metrics"
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"tailscale.com/tsweb/varz"
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)
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var vars expvar.Map
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// NewMultiLabelMap creates and register a new
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// MultiLabelMap[T] variable with the given name and returns it.
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// The variable is registered with the userfacing metrics package.
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//
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// Note that usermetric are not protected against duplicate
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// metrics name. It is the caller's responsibility to ensure that
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// the name is unique.
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func NewMultiLabelMap[T comparable](name string, promType, helpText string) *metrics.MultiLabelMap[T] {
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m := &metrics.MultiLabelMap[T]{
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Type: promType,
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Help: helpText,
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}
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var zero T
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_ = metrics.LabelString(zero) // panic early if T is invalid
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vars.Set(name, m)
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return m
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}
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// Gauge is a gauge metric with no labels.
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type Gauge struct {
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m *expvar.Float
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help string
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}
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// NewGauge creates and register a new gauge metric with the given name and help text.
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func NewGauge(name, help string) *Gauge {
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g := &Gauge{&expvar.Float{}, help}
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vars.Set(name, g)
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return g
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}
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// Set sets the gauge to the given value.
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func (g *Gauge) Set(v float64) {
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g.m.Set(v)
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}
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// String returns the string of the underlying expvar.Float.
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// This satisfies the expvar.Var interface.
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func (g *Gauge) String() string {
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return g.m.String()
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}
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// WritePrometheus writes the gauge metric in Prometheus format to the given writer.
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// This satisfies the varz.PrometheusWriter interface.
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func (g *Gauge) WritePrometheus(w io.Writer, name string) {
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io.WriteString(w, "# TYPE ")
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io.WriteString(w, name)
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io.WriteString(w, " gauge\n")
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if g.help != "" {
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io.WriteString(w, "# HELP ")
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io.WriteString(w, name)
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io.WriteString(w, " ")
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io.WriteString(w, g.help)
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io.WriteString(w, "\n")
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}
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io.WriteString(w, name)
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fmt.Fprintf(w, " %v\n", g.m.Value())
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}
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// Handler returns a varz.Handler that serves the userfacing expvar contained
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// in this package.
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func Handler(w http.ResponseWriter, r *http.Request) {
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varz.ExpvarDoHandler(vars.Do)(w, r)
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}
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@ -0,0 +1,25 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package usermetric
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import (
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"bytes"
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"testing"
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)
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func TestGauge(t *testing.T) {
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g := NewGauge("test_gauge", "This is a test gauge")
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g.Set(15)
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var buf bytes.Buffer
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g.WritePrometheus(&buf, "test_gauge")
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const want = `# TYPE test_gauge gauge
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# HELP test_gauge This is a test gauge
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test_gauge 15
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`
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if got := buf.String(); got != want {
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t.Errorf("got %q; want %q", got, want)
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}
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}
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