metrics

package
v1.94.2 Latest Latest
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 Go to latest Published: Feb 13, 2026 License: BSD-3-Clause Imports: 12 Imported by: 23

Documentation

Overview

Package metrics contains expvar & Prometheus types and code used by Tailscale for monitoring.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func CurrentFDs added in v1.16.0 

func CurrentFDs() int

CurrentFDs reports how many file descriptors are currently open.

It only works on Linux. It returns zero otherwise.

func LabelString added in v1.74.0 

func LabelString(k any) string

LabelString returns a Prometheus-formatted label string for the given key. k must be a struct type with scalar fields, as required by MultiLabelMap, if k is not a struct, it will panic.

Types

type Histogram added in v1.46.0 

type Histogram struct {
	// contains filtered or unexported fields
}

Histogram is a histogram of values. It should be created with NewHistogram.

func NewHistogram added in v1.46.0 

func NewHistogram(buckets []float64) *Histogram

NewHistogram returns a new histogram that reports to the given expvar map under the given name.

The buckets are the boundaries of the histogram buckets, in increasing order. The last bucket is +Inf.

func (*Histogram) Do added in v1.46.0 

func (h *Histogram) Do(f func(expvar.KeyValue))

Do calls f for each bucket in the histogram.

func (*Histogram) Observe added in v1.46.0 

func (h *Histogram) Observe(v float64)

Observe records a new observation in the histogram.

func (*Histogram) PromExport added in v1.46.0 

func (h *Histogram) PromExport(w io.Writer, name string)

PromExport writes the histogram to w in Prometheus exposition format.

func (*Histogram) String added in v1.46.0 

func (h *Histogram) String() string

String returns a JSON representation of the histogram. This is used to satisfy the expvar.Var interface.

type KeyValue added in v1.64.0 

type KeyValue[T comparable] struct {
	Key   T
	Value expvar.Var
}

KeyValue represents a single entry in a MultiLabelMap.

type LabelMap 

type LabelMap struct {
	Label string
	expvar.Map
	// contains filtered or unexported fields
}

LabelMap is a string-to-Var map variable that satisfies the expvar.Var interface.

Semantically, this is mapped by tsweb's Prometheus exporter as a collection of variables with the same name, with a varying label value. Use this to export things that are intuitively breakdowns into different buckets.

func NewLabelMap added in v1.94.0 

func NewLabelMap(metric, label string) *LabelMap

NewLabelMap creates and publishes a new LabelMap metric with the given metric name and label name.

func (*LabelMap) Add added in v1.80.0 

func (m *LabelMap) Add(key string, delta int64)

Add adds delta to the any int-like value stored under the given map key.

func (*LabelMap) Get 

func (m *LabelMap) Get(key string) *expvar.Int

Get returns a direct pointer to the expvar.Int for key, creating it if necessary.

func (*LabelMap) GetFloat added in v1.0.0 

func (m *LabelMap) GetFloat(key string) *expvar.Float

GetFloat returns a direct pointer to the expvar.Float for key, creating it if necessary.

func (*LabelMap) GetIncrFunc added in v1.46.0 

func (m *LabelMap) GetIncrFunc(key string) func(delta int64)

GetIncrFunc returns a function that increments the expvar.Int named by key.

Most callers should not need this; it exists to satisfy an interface elsewhere.

func (*LabelMap) GetShardedInt added in v1.80.0 

func (m *LabelMap) GetShardedInt(key string) *syncs.ShardedInt

GetShardedInt returns a direct pointer to the syncs.ShardedInt for key, creating it if necessary.

func (*LabelMap) SetInt64 added in v1.38.0 

func (m *LabelMap) SetInt64(key string, v int64)

SetInt64 sets the *Int value stored under the given map key.

type MultiLabelMap added in v1.64.0 

type MultiLabelMap[T comparable] struct {
	Type string // optional Prometheus type ("counter", "gauge")
	Help string // optional Prometheus help string
	// contains filtered or unexported fields
}

MultiLabelMap is a struct-value-to-Var map variable that satisfies the expvar.Var interface but also allows for multiple Prometheus labels to be associated with each value.

T must be a struct type with scalar fields. The struct field names (lowercased) are used as the labels, unless a "prom" struct tag is present. The struct fields must all be strings, and the string values must be valid Prometheus label values without requiring quoting.

func NewMultiLabelMap added in v1.64.0 

func NewMultiLabelMap[T comparable](name string, promType, helpText string) *MultiLabelMap[T]

NewMultiLabelMap creates and publishes (via expvar.Publish) a new MultiLabelMap[T] variable with the given name and returns it.

func (*MultiLabelMap[T]) Add added in v1.64.0 

func (v *MultiLabelMap[T]) Add(key T, delta int64)

Add adds delta to the *expvar.Int value stored under the given map key, creating it if it doesn't exist yet. It does nothing if key exists but is of the wrong type.

func (*MultiLabelMap[T]) AddFloat added in v1.64.0 

func (v *MultiLabelMap[T]) AddFloat(key T, delta float64)

Add adds delta to the *expvar.Float value stored under the given map key, creating it if it doesn't exist yet. It does nothing if key exists but is of the wrong type.

func (*MultiLabelMap[T]) Delete added in v1.64.0 

func (v *MultiLabelMap[T]) Delete(key T)

Delete deletes the given key from the map.

This is not optimized for highly concurrent usage; it's presumed to only be used rarely, at startup.

func (*MultiLabelMap[T]) Do added in v1.64.0 

func (v *MultiLabelMap[T]) Do(f func(KeyValue[T]))

Do calls f for each entry in the map. The map is locked during the iteration, but existing entries may be concurrently updated.

func (*MultiLabelMap[T]) Get added in v1.64.0 

func (v *MultiLabelMap[T]) Get(key T) expvar.Var

Get returns the expvar for the given key, or nil if it doesn't exist.

func (*MultiLabelMap[T]) Init added in v1.64.0 

func (v *MultiLabelMap[T]) Init() *MultiLabelMap[T]

Init removes all keys from the map.

Think of it as "Reset", but it's named Init to match expvar.Map.Init.

func (*MultiLabelMap[T]) ResetAllForTest added in v1.76.0 

func (v *MultiLabelMap[T]) ResetAllForTest()

ResetAllForTest resets all values for metrics to zero. Should only be used in tests.

func (*MultiLabelMap[T]) Set added in v1.64.0 

func (v *MultiLabelMap[T]) Set(key T, val expvar.Var)

Set sets key to val.

This is not optimized for highly concurrent usage; it's presumed to only be used rarely, at startup.

func (*MultiLabelMap[T]) SetFloat added in v1.74.0 

func (v *MultiLabelMap[T]) SetFloat(key T, val float64)

SetFloat sets val to the *expvar.Float value stored under the given map key, creating it if it doesn't exist yet. It does nothing if key exists but is of the wrong type.

func (*MultiLabelMap[T]) SetInt added in v1.74.0 

func (v *MultiLabelMap[T]) SetInt(key T, val int64)

SetInt sets val to the *expvar.Int value stored under the given map key, creating it if it doesn't exist yet. It does nothing if key exists but is of the wrong type.

func (*MultiLabelMap[T]) String added in v1.64.0 

func (v *MultiLabelMap[T]) String() string

func (*MultiLabelMap[T]) WritePrometheus added in v1.64.0 

func (v *MultiLabelMap[T]) WritePrometheus(w io.Writer, name string)

WritePrometheus writes v to w in Prometheus exposition format. The name argument is the metric name.

type Set 

type Set struct {
	expvar.Map
}

Set is a string-to-Var map variable that satisfies the expvar.Var interface.

Semantically, this is mapped by tsweb's Prometheus exporter as a collection of unrelated variables exported with a common prefix.

This lets us have tsweb recognize *expvar.Map for different purposes in the future. (Or perhaps all uses of expvar.Map will require explicit types like this one, declaring how we want tsweb to export it to Prometheus.)

func NewSet added in v1.94.0 

func NewSet(name string) *Set

NewSet creates and publishes a new Set with the given name.

func (*Set) NewLabelMap added in v1.94.0 

func (s *Set) NewLabelMap(metric, label string) *LabelMap

NewLabelMap creates a new LabelMap metric with the given metric name and label name, and adds it to the Set.

Source Files

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