telegraf/plugins/outputs/prometheus_client/prometheus_client.go

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package prometheus_client
import (
"context"
"fmt"
"log"
"net/http"
"regexp"
"sort"
"strings"
"sync"
"time"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/plugins/outputs"
"github.com/prometheus/client_golang/prometheus"
)
var invalidNameCharRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
// SampleID uniquely identifies a Sample
type SampleID string
// Sample represents the current value of a series.
type Sample struct {
// Labels are the Prometheus labels.
Labels map[string]string
// Value is the value in the Prometheus output.
Value float64
// Expiration is the deadline that this Sample is valid until.
Expiration time.Time
}
// MetricFamily contains the data required to build valid prometheus Metrics.
type MetricFamily struct {
// Samples are the Sample belonging to this MetricFamily.
Samples map[SampleID]*Sample
// Type of the Value.
ValueType prometheus.ValueType
// LabelSet is the label counts for all Samples.
LabelSet map[string]int
}
type PrometheusClient struct {
Listen string
ExpirationInterval internal.Duration `toml:"expiration_interval"`
server *http.Server
sync.Mutex
// fam is the non-expired MetricFamily by Prometheus metric name.
fam map[string]*MetricFamily
// now returns the current time.
now func() time.Time
}
var sampleConfig = `
## Address to listen on
# listen = ":9273"
## Interval to expire metrics and not deliver to prometheus, 0 == no expiration
# expiration_interval = "60s"
`
func (p *PrometheusClient) Start() error {
prometheus.Register(p)
if p.Listen == "" {
p.Listen = "localhost:9273"
}
mux := http.NewServeMux()
mux.Handle("/metrics", prometheus.Handler())
p.server = &http.Server{
Addr: p.Listen,
Handler: mux,
}
go func() {
if err := p.server.ListenAndServe(); err != nil {
log.Printf("E! Error creating prometheus metric endpoint, err: %s\n",
err.Error())
}
}()
return nil
}
func (p *PrometheusClient) Stop() {
// plugin gets cleaned up in Close() already.
}
func (p *PrometheusClient) Connect() error {
// This service output does not need to make any further connections
return nil
}
func (p *PrometheusClient) Close() error {
ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
defer cancel()
return p.server.Shutdown(ctx)
}
func (p *PrometheusClient) SampleConfig() string {
return sampleConfig
}
func (p *PrometheusClient) Description() string {
return "Configuration for the Prometheus client to spawn"
}
// Implements prometheus.Collector
func (p *PrometheusClient) Describe(ch chan<- *prometheus.Desc) {
prometheus.NewGauge(prometheus.GaugeOpts{Name: "Dummy", Help: "Dummy"}).Describe(ch)
}
// Expire removes Samples that have expired.
func (p *PrometheusClient) Expire() {
now := p.now()
for name, family := range p.fam {
for key, sample := range family.Samples {
if p.ExpirationInterval.Duration != 0 && now.After(sample.Expiration) {
for k, _ := range sample.Labels {
family.LabelSet[k]--
}
delete(family.Samples, key)
if len(family.Samples) == 0 {
delete(p.fam, name)
}
}
}
}
}
// Collect implements prometheus.Collector
func (p *PrometheusClient) Collect(ch chan<- prometheus.Metric) {
p.Lock()
defer p.Unlock()
p.Expire()
for name, family := range p.fam {
// Get list of all labels on MetricFamily
var labelNames []string
for k, v := range family.LabelSet {
if v > 0 {
labelNames = append(labelNames, k)
}
}
desc := prometheus.NewDesc(name, "Telegraf collected metric", labelNames, nil)
for _, sample := range family.Samples {
// Get labels for this sample; unset labels will be set to the
// empty string
var labels []string
for _, label := range labelNames {
v := sample.Labels[label]
labels = append(labels, v)
}
metric, err := prometheus.NewConstMetric(desc, family.ValueType, sample.Value, labels...)
if err != nil {
log.Printf("E! Error creating prometheus metric, "+
"key: %s, labels: %v,\nerr: %s\n",
name, labels, err.Error())
}
ch <- metric
}
}
}
func sanitize(value string) string {
return invalidNameCharRE.ReplaceAllString(value, "_")
}
func valueType(tt telegraf.ValueType) prometheus.ValueType {
switch tt {
case telegraf.Counter:
return prometheus.CounterValue
case telegraf.Gauge:
return prometheus.GaugeValue
default:
return prometheus.UntypedValue
}
}
// CreateSampleID creates a SampleID based on the tags of a telegraf.Metric.
func CreateSampleID(tags map[string]string) SampleID {
pairs := make([]string, 0, len(tags))
for k, v := range tags {
pairs = append(pairs, fmt.Sprintf("%s=%s", k, v))
}
sort.Strings(pairs)
return SampleID(strings.Join(pairs, ","))
}
func (p *PrometheusClient) Write(metrics []telegraf.Metric) error {
p.Lock()
defer p.Unlock()
now := p.now()
for _, point := range metrics {
tags := point.Tags()
vt := valueType(point.Type())
sampleID := CreateSampleID(tags)
labels := make(map[string]string)
for k, v := range tags {
labels[sanitize(k)] = v
}
for fn, fv := range point.Fields() {
// Ignore string and bool fields.
var value float64
switch fv := fv.(type) {
case int64:
value = float64(fv)
case float64:
value = fv
default:
continue
}
sample := &Sample{
Labels: labels,
Value: value,
Expiration: now.Add(p.ExpirationInterval.Duration),
}
// Special handling of value field; supports passthrough from
// the prometheus input.
var mname string
if fn == "value" {
mname = sanitize(point.Name())
} else {
mname = sanitize(fmt.Sprintf("%s_%s", point.Name(), fn))
}
var fam *MetricFamily
var ok bool
if fam, ok = p.fam[mname]; !ok {
fam = &MetricFamily{
Samples: make(map[SampleID]*Sample),
ValueType: vt,
LabelSet: make(map[string]int),
}
p.fam[mname] = fam
} else {
if fam.ValueType != vt {
// Don't return an error since this would be a permanent error
log.Printf("Mixed ValueType for measurement %q; dropping point", point.Name())
break
}
}
for k, _ := range sample.Labels {
fam.LabelSet[k]++
}
fam.Samples[sampleID] = sample
}
}
return nil
}
func init() {
outputs.Add("prometheus_client", func() telegraf.Output {
return &PrometheusClient{
ExpirationInterval: internal.Duration{Duration: time.Second * 60},
fam: make(map[string]*MetricFamily),
now: time.Now,
}
})
}