groupcache_exporter

README

Prometheus Groupcache exporter

This exporter implements the prometheus.Collector interface in order to expose Prometheus metrics for groupcache.

Example for mailgun groupcache

import "github.com/udhos/groupcache_exporter/groupcache/mailgun"

// ...

appName := filepath.Base(os.Args[0])

cache := startGroupcache()

//
// expose prometheus metrics
//
{
    metricsRoute := "/metrics"
    metricsPort := ":3000"

    log.Printf("starting metrics server at: %s %s", metricsPort, metricsRoute)

    mailgun := mailgun.New(cache)
    labels := map[string]string{
        "app": appName,
    }
    namespace := ""
    collector := groupcache_exporter.NewExporter(namespace, labels, mailgun)

    prometheus.MustRegister(collector)

    go func() {
        http.Handle(metricsRoute, promhttp.Handler())
        log.Fatal(http.ListenAndServe(metricsPort, nil))
    }()
}

Full example: examples/groupcache-exporter-mailgun

Example for modernprogram groupcache

import "github.com/udhos/groupcache_exporter/groupcache/modernprogram"

// ...

appName := filepath.Base(os.Args[0])

cache := startGroupcache()

//
// expose prometheus metrics
//
{
    metricsRoute := "/metrics"
    metricsPort := ":3000"

    log.Printf("starting metrics server at: %s %s", metricsPort, metricsRoute)

    modernprogram := modernprogram.New(cache)
    labels := map[string]string{
        "app": appName,
    }
    namespace := ""
    collector := groupcache_exporter.NewExporter(namespace, labels, modernprogram)

    prometheus.MustRegister(collector)

    go func() {
        http.Handle(metricsRoute, promhttp.Handler())
        log.Fatal(http.ListenAndServe(metricsPort, nil))
    }()
}

Full example: examples/groupcache-exporter-modernprogram

Testing

Build

go install ./...

Run example application

groupcache-exporter-mailgun

Query the metrics endpoint

curl -s localhost:3000/metrics | grep -E ^groupcache
groupcache_cache_bytes{app="groupcache-exporter-mailgun",group="files",type="hot"} 0
groupcache_cache_bytes{app="groupcache-exporter-mailgun",group="files",type="main"} 2954
groupcache_cache_evictions_total{app="groupcache-exporter-mailgun",group="files",type="hot"} 0
groupcache_cache_evictions_total{app="groupcache-exporter-mailgun",group="files",type="main"} 1
groupcache_cache_gets_total{app="groupcache-exporter-mailgun",group="files",type="hot"} 4
groupcache_cache_gets_total{app="groupcache-exporter-mailgun",group="files",type="main"} 16
groupcache_cache_hits_total{app="groupcache-exporter-mailgun",group="files",type="hot"} 0
groupcache_cache_hits_total{app="groupcache-exporter-mailgun",group="files",type="main"} 12
groupcache_cache_items{app="groupcache-exporter-mailgun",group="files",type="hot"} 0
groupcache_cache_items{app="groupcache-exporter-mailgun",group="files",type="main"} 1
groupcache_gets_total{app="groupcache-exporter-mailgun",group="files"} 14
groupcache_hits_total{app="groupcache-exporter-mailgun",group="files"} 12
groupcache_loads_deduped_total{app="groupcache-exporter-mailgun",group="files"} 2
groupcache_loads_total{app="groupcache-exporter-mailgun",group="files"} 2
groupcache_local_load_errs_total{app="groupcache-exporter-mailgun",group="files"} 0
groupcache_local_load_total{app="groupcache-exporter-mailgun",group="files"} 2
groupcache_peer_errors_total{app="groupcache-exporter-mailgun",group="files"} 0
groupcache_peer_loads_total{app="groupcache-exporter-mailgun",group="files"} 0
groupcache_server_requests_total{app="groupcache-exporter-mailgun",group="files"} 0

Documentation

Overview

Package groupcache_exporter exports prometheus metrics for groupcache.

Index

• type CacheDelta
  • func GetCacheDelta(prev, curr GroupStats) CacheDelta
• type CacheTypeDelta
  • func GetCacheTypeDelta(prev, curr CacheTypeStats) CacheTypeDelta
• type CacheTypeStats
• type Exporter
  • func NewExporter(options Options) *Exporter
  • func (e *Exporter) Collect(ch chan<- prometheus.Metric)
  • func (e *Exporter) Describe(ch chan<- *prometheus.Desc)
• type GroupStatistics
• type GroupStats
• type Options
• type Stats

Types

type CacheDelta

type CacheDelta struct {
	Gets              int64
	Hits              int64
	PeerLoads         int64
	PeerErrors        int64
	Loads             int64
	LoadsDeduped      int64
	LocalLoads        int64
	LocalLoadsErrs    int64
	ServerRequests    int64
	CrosstalkRefusals int64
}

CacheDelta represents deltas for cache stats.

func GetCacheDelta

func GetCacheDelta(prev, curr GroupStats) CacheDelta

GetCacheDelta calculates deltas for cache stats.

type CacheTypeDelta

type CacheTypeDelta struct {
	Gets                int64
	Hits                int64
	Evictions           int64
	EvictionsNonExpired int64
}

CacheTypeDelta represents deltas for per-type cache stats.

func GetCacheTypeDelta

func GetCacheTypeDelta(prev, curr CacheTypeStats) CacheTypeDelta

GetCacheTypeDelta calculates deltas for per-type cache stats.

type CacheTypeStats

type CacheTypeStats struct {
	// GaugeCacheItems represents number of items in the main/hot cache
	GaugeCacheItems int64

	// GaugeCacheBytes represents number of bytes in the main/hot cache
	GaugeCacheBytes int64

	// CounterCacheGets represents number of get requests in the main/hot cache
	CounterCacheGets int64

	// CounterCacheHits represents number of hit in the main/hot cache
	CounterCacheHits int64

	// CounterCacheEvictions represents number of evictions in the main/hot cache
	CounterCacheEvictions int64

	// CounterCacheEvictionsNonExpired represents number of evictions for non-expired keys in the main/hot cache
	CounterCacheEvictionsNonExpired int64
}

CacheTypeStats holds stats for the main cache or the hot cache.

type Exporter

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

Exporter implements interface prometheus.Collector to extract metrics from groupcache.

func NewExporter

func NewExporter(options Options) *Exporter

NewExporter creates Exporter. namespace is usually the empty string.

func (*Exporter) Collect

func (e *Exporter) Collect(ch chan<- prometheus.Metric)

Collect is called by the Prometheus registry when collecting metrics.

func (*Exporter) Describe

func (e *Exporter) Describe(ch chan<- *prometheus.Desc)

Describe sends metrics descriptors.

type GroupStatistics

type GroupStatistics interface {
	// Collect requests metrics collection from implementation
	Collect() Stats

	// Name returns the group's name
	Name() string
}

GroupStatistics is a plugable interface to extract metrics from a groupcache implementation. GroupStatistics is used by Exporter to collect the group statistics. The user must provide a concrete implementation of this interface that knows how to extract group statistics from the actual groupcache implementation.

type GroupStats

type GroupStats struct {

	// CounterGets represents any Get request, including from peers
	CounterGets int64

	// CounterHits represents either cache was good
	CounterHits int64

	// GaugeGetFromPeersLatencyLower represents slowest duration to request value from peers
	GaugeGetFromPeersLatencyLower float64

	// CounterPeerLoads represents either remote load or remote cache hit (not an error)
	CounterPeerLoads int64

	// CounterPeerErrors represents a count of errors from peers
	CounterPeerErrors int64

	// CounterLoads represents (gets - cacheHits)
	CounterLoads int64

	// CounterLoadsDeduped represents after singleflight
	CounterLoadsDeduped int64

	// CounterLocalLoads represents total good local loads
	CounterLocalLoads int64

	// CounterLocalLoadsErrs represents total bad local loads
	CounterLocalLoadsErrs int64

	// CounterServerRequests represents gets that came over the network from peers
	CounterServerRequests int64

	// CounterCrosstalkRefusals represents refusals for additional crosstalks
	CounterCrosstalkRefusals int64
}

GroupStats holds general stats for the group.

type Options

type Options struct {
	Namespace  string
	Labels     map[string]string
	Debug      bool
	ListGroups func() []GroupStatistics
}

Options define parameters for Exporter.

type Stats

type Stats struct {
	// Group holds general stats for the group.
	Group GroupStats

	// Main holds stats for the group main cache.
	Main CacheTypeStats

	// Hot holds stats for the group hot cache.
	Hot CacheTypeStats
}

Stats holds full stats for the group.