|
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295 |
- // Copyright 2017, OpenCensus Authors
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
-
- // Package prometheus contains a Prometheus exporter that supports exporting
- // OpenCensus views as Prometheus metrics.
- package prometheus // import "go.opencensus.io/exporter/prometheus"
-
- import (
- "bytes"
- "fmt"
- "log"
- "net/http"
- "sync"
-
- "go.opencensus.io/internal"
- "go.opencensus.io/stats/view"
- "go.opencensus.io/tag"
-
- "github.com/prometheus/client_golang/prometheus"
- "github.com/prometheus/client_golang/prometheus/promhttp"
- )
-
- // Exporter exports stats to Prometheus, users need
- // to register the exporter as an http.Handler to be
- // able to export.
- type Exporter struct {
- opts Options
- g prometheus.Gatherer
- c *collector
- handler http.Handler
- }
-
- // Options contains options for configuring the exporter.
- type Options struct {
- Namespace string
- Registry *prometheus.Registry
- OnError func(err error)
- ConstLabels prometheus.Labels // ConstLabels will be set as labels on all views.
- }
-
- // NewExporter returns an exporter that exports stats to Prometheus.
- func NewExporter(o Options) (*Exporter, error) {
- if o.Registry == nil {
- o.Registry = prometheus.NewRegistry()
- }
- collector := newCollector(o, o.Registry)
- e := &Exporter{
- opts: o,
- g: o.Registry,
- c: collector,
- handler: promhttp.HandlerFor(o.Registry, promhttp.HandlerOpts{}),
- }
- return e, nil
- }
-
- var _ http.Handler = (*Exporter)(nil)
- var _ view.Exporter = (*Exporter)(nil)
-
- func (c *collector) registerViews(views ...*view.View) {
- count := 0
- for _, view := range views {
- sig := viewSignature(c.opts.Namespace, view)
- c.registeredViewsMu.Lock()
- _, ok := c.registeredViews[sig]
- c.registeredViewsMu.Unlock()
-
- if !ok {
- desc := prometheus.NewDesc(
- viewName(c.opts.Namespace, view),
- view.Description,
- tagKeysToLabels(view.TagKeys),
- c.opts.ConstLabels,
- )
- c.registeredViewsMu.Lock()
- c.registeredViews[sig] = desc
- c.registeredViewsMu.Unlock()
- count++
- }
- }
- if count == 0 {
- return
- }
-
- c.ensureRegisteredOnce()
- }
-
- // ensureRegisteredOnce invokes reg.Register on the collector itself
- // exactly once to ensure that we don't get errors such as
- // cannot register the collector: descriptor Desc{fqName: *}
- // already exists with the same fully-qualified name and const label values
- // which is documented by Prometheus at
- // https://github.com/prometheus/client_golang/blob/fcc130e101e76c5d303513d0e28f4b6d732845c7/prometheus/registry.go#L89-L101
- func (c *collector) ensureRegisteredOnce() {
- c.registerOnce.Do(func() {
- if err := c.reg.Register(c); err != nil {
- c.opts.onError(fmt.Errorf("cannot register the collector: %v", err))
- }
- })
-
- }
-
- func (o *Options) onError(err error) {
- if o.OnError != nil {
- o.OnError(err)
- } else {
- log.Printf("Failed to export to Prometheus: %v", err)
- }
- }
-
- // ExportView exports to the Prometheus if view data has one or more rows.
- // Each OpenCensus AggregationData will be converted to
- // corresponding Prometheus Metric: SumData will be converted
- // to Untyped Metric, CountData will be a Counter Metric,
- // DistributionData will be a Histogram Metric.
- func (e *Exporter) ExportView(vd *view.Data) {
- if len(vd.Rows) == 0 {
- return
- }
- e.c.addViewData(vd)
- }
-
- // ServeHTTP serves the Prometheus endpoint.
- func (e *Exporter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
- e.handler.ServeHTTP(w, r)
- }
-
- // collector implements prometheus.Collector
- type collector struct {
- opts Options
- mu sync.Mutex // mu guards all the fields.
-
- registerOnce sync.Once
-
- // reg helps collector register views dynamically.
- reg *prometheus.Registry
-
- // viewData are accumulated and atomically
- // appended to on every Export invocation, from
- // stats. These views are cleared out when
- // Collect is invoked and the cycle is repeated.
- viewData map[string]*view.Data
-
- registeredViewsMu sync.Mutex
- // registeredViews maps a view to a prometheus desc.
- registeredViews map[string]*prometheus.Desc
- }
-
- func (c *collector) addViewData(vd *view.Data) {
- c.registerViews(vd.View)
- sig := viewSignature(c.opts.Namespace, vd.View)
-
- c.mu.Lock()
- c.viewData[sig] = vd
- c.mu.Unlock()
- }
-
- func (c *collector) Describe(ch chan<- *prometheus.Desc) {
- c.registeredViewsMu.Lock()
- registered := make(map[string]*prometheus.Desc)
- for k, desc := range c.registeredViews {
- registered[k] = desc
- }
- c.registeredViewsMu.Unlock()
-
- for _, desc := range registered {
- ch <- desc
- }
- }
-
- // Collect fetches the statistics from OpenCensus
- // and delivers them as Prometheus Metrics.
- // Collect is invoked everytime a prometheus.Gatherer is run
- // for example when the HTTP endpoint is invoked by Prometheus.
- func (c *collector) Collect(ch chan<- prometheus.Metric) {
- // We need a copy of all the view data up until this point.
- viewData := c.cloneViewData()
-
- for _, vd := range viewData {
- sig := viewSignature(c.opts.Namespace, vd.View)
- c.registeredViewsMu.Lock()
- desc := c.registeredViews[sig]
- c.registeredViewsMu.Unlock()
-
- for _, row := range vd.Rows {
- metric, err := c.toMetric(desc, vd.View, row)
- if err != nil {
- c.opts.onError(err)
- } else {
- ch <- metric
- }
- }
- }
-
- }
-
- func (c *collector) toMetric(desc *prometheus.Desc, v *view.View, row *view.Row) (prometheus.Metric, error) {
- switch data := row.Data.(type) {
- case *view.CountData:
- return prometheus.NewConstMetric(desc, prometheus.CounterValue, float64(data.Value), tagValues(row.Tags, v.TagKeys)...)
-
- case *view.DistributionData:
- points := make(map[float64]uint64)
- // Histograms are cumulative in Prometheus.
- // Get cumulative bucket counts.
- cumCount := uint64(0)
- for i, b := range v.Aggregation.Buckets {
- cumCount += uint64(data.CountPerBucket[i])
- points[b] = cumCount
- }
- return prometheus.NewConstHistogram(desc, uint64(data.Count), data.Sum(), points, tagValues(row.Tags, v.TagKeys)...)
-
- case *view.SumData:
- return prometheus.NewConstMetric(desc, prometheus.UntypedValue, data.Value, tagValues(row.Tags, v.TagKeys)...)
-
- case *view.LastValueData:
- return prometheus.NewConstMetric(desc, prometheus.GaugeValue, data.Value, tagValues(row.Tags, v.TagKeys)...)
-
- default:
- return nil, fmt.Errorf("aggregation %T is not yet supported", v.Aggregation)
- }
- }
-
- func tagKeysToLabels(keys []tag.Key) (labels []string) {
- for _, key := range keys {
- labels = append(labels, internal.Sanitize(key.Name()))
- }
- return labels
- }
-
- func newCollector(opts Options, registrar *prometheus.Registry) *collector {
- return &collector{
- reg: registrar,
- opts: opts,
- registeredViews: make(map[string]*prometheus.Desc),
- viewData: make(map[string]*view.Data),
- }
- }
-
- func tagValues(t []tag.Tag, expectedKeys []tag.Key) []string {
- var values []string
- // Add empty string for all missing keys in the tags map.
- idx := 0
- for _, t := range t {
- for t.Key != expectedKeys[idx] {
- idx++
- values = append(values, "")
- }
- values = append(values, t.Value)
- idx++
- }
- for idx < len(expectedKeys) {
- idx++
- values = append(values, "")
- }
- return values
- }
-
- func viewName(namespace string, v *view.View) string {
- var name string
- if namespace != "" {
- name = namespace + "_"
- }
- return name + internal.Sanitize(v.Name)
- }
-
- func viewSignature(namespace string, v *view.View) string {
- var buf bytes.Buffer
- buf.WriteString(viewName(namespace, v))
- for _, k := range v.TagKeys {
- buf.WriteString("-" + k.Name())
- }
- return buf.String()
- }
-
- func (c *collector) cloneViewData() map[string]*view.Data {
- c.mu.Lock()
- defer c.mu.Unlock()
-
- viewDataCopy := make(map[string]*view.Data)
- for sig, viewData := range c.viewData {
- viewDataCopy[sig] = viewData
- }
- return viewDataCopy
- }
|