Initial QSfera import
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Курнат Андрей
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// Copyright 2017, OpenCensus Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package prometheus contains a Prometheus exporter that supports exporting
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// OpenCensus views as Prometheus metrics.
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package prometheus // import "contrib.go.opencensus.io/exporter/prometheus"
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import (
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"context"
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"fmt"
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"log"
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"net/http"
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"sync"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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"go.opencensus.io/metric/metricdata"
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"go.opencensus.io/metric/metricexport"
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"go.opencensus.io/stats/view"
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)
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// Exporter exports stats to Prometheus, users need
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// to register the exporter as an http.Handler to be
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// able to export.
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type Exporter struct {
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opts Options
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g prometheus.Gatherer
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c *collector
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handler http.Handler
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}
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// Options contains options for configuring the exporter.
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type Options struct {
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Namespace string
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Registry *prometheus.Registry
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Registerer prometheus.Registerer
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Gatherer prometheus.Gatherer
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OnError func(err error)
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ConstLabels prometheus.Labels // ConstLabels will be set as labels on all views.
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}
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// NewExporter returns an exporter that exports stats to Prometheus.
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func NewExporter(o Options) (*Exporter, error) {
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if o.Registry == nil {
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o.Registry = prometheus.NewRegistry()
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}
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if o.Registerer == nil {
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o.Registerer = o.Registry
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}
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if o.Gatherer == nil {
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o.Gatherer = o.Registry
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}
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collector := newCollector(o, o.Registerer)
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e := &Exporter{
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opts: o,
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g: o.Gatherer,
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c: collector,
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handler: promhttp.HandlerFor(o.Gatherer, promhttp.HandlerOpts{}),
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}
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collector.ensureRegisteredOnce()
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return e, nil
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}
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var _ http.Handler = (*Exporter)(nil)
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// ensureRegisteredOnce invokes reg.Register on the collector itself
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// exactly once to ensure that we don't get errors such as
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// cannot register the collector: descriptor Desc{fqName: *}
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// already exists with the same fully-qualified name and const label values
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// which is documented by Prometheus at
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// https://github.com/prometheus/client_golang/blob/fcc130e101e76c5d303513d0e28f4b6d732845c7/prometheus/registry.go#L89-L101
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func (c *collector) ensureRegisteredOnce() {
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c.registerOnce.Do(func() {
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if err := c.reg.Register(c); err != nil {
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c.opts.onError(fmt.Errorf("cannot register the collector: %v", err))
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}
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})
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}
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func (o *Options) onError(err error) {
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if o.OnError != nil {
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o.OnError(err)
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} else {
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log.Printf("Failed to export to Prometheus: %v", err)
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}
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}
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// ExportView exports to the Prometheus if view data has one or more rows.
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// Each OpenCensus AggregationData will be converted to
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// corresponding Prometheus Metric: SumData will be converted
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// to Untyped Metric, CountData will be a Counter Metric,
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// DistributionData will be a Histogram Metric.
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//
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// Deprecated: in lieu of metricexport.Reader interface.
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func (e *Exporter) ExportView(vd *view.Data) {
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}
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// ServeHTTP serves the Prometheus endpoint.
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func (e *Exporter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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e.handler.ServeHTTP(w, r)
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}
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// collector implements prometheus.Collector
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type collector struct {
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opts Options
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registerOnce sync.Once
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// reg helps collector register views dynamically.
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reg prometheus.Registerer
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// reader reads metrics from all registered producers.
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reader *metricexport.Reader
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}
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func (c *collector) Describe(ch chan<- *prometheus.Desc) {
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de := &descExporter{c: c, descCh: ch}
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c.reader.ReadAndExport(de)
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}
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// Collect fetches the statistics from OpenCensus
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// and delivers them as Prometheus Metrics.
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// Collect is invoked every time a prometheus.Gatherer is run
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// for example when the HTTP endpoint is invoked by Prometheus.
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func (c *collector) Collect(ch chan<- prometheus.Metric) {
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me := &metricExporter{c: c, metricCh: ch}
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c.reader.ReadAndExport(me)
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}
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func newCollector(opts Options, registrar prometheus.Registerer) *collector {
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return &collector{
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reg: registrar,
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opts: opts,
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reader: metricexport.NewReader()}
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}
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func (c *collector) toDesc(metric *metricdata.Metric) *prometheus.Desc {
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var labels prometheus.Labels
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switch {
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case metric.Resource == nil:
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labels = c.opts.ConstLabels
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case c.opts.ConstLabels == nil:
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labels = metric.Resource.Labels
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default:
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labels = prometheus.Labels{}
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for k, v := range c.opts.ConstLabels {
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labels[k] = v
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}
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// Resource labels overwrite const labels.
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for k, v := range metric.Resource.Labels {
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labels[k] = v
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}
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}
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return prometheus.NewDesc(
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metricName(c.opts.Namespace, metric),
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metric.Descriptor.Description,
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toPromLabels(metric.Descriptor.LabelKeys),
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labels)
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}
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type metricExporter struct {
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c *collector
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metricCh chan<- prometheus.Metric
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}
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// ExportMetrics exports to the Prometheus.
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// Each OpenCensus Metric will be converted to
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// corresponding Prometheus Metric:
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// TypeCumulativeInt64 and TypeCumulativeFloat64 will be a Counter Metric,
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// TypeCumulativeDistribution will be a Histogram Metric.
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// TypeGaugeFloat64 and TypeGaugeInt64 will be a Gauge Metric
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func (me *metricExporter) ExportMetrics(ctx context.Context, metrics []*metricdata.Metric) error {
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for _, metric := range metrics {
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desc := me.c.toDesc(metric)
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for _, ts := range metric.TimeSeries {
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tvs := toLabelValues(ts.LabelValues)
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for _, point := range ts.Points {
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metric, err := toPromMetric(desc, metric, point, tvs)
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if err != nil {
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me.c.opts.onError(err)
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} else if metric != nil {
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me.metricCh <- metric
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}
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}
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}
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}
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return nil
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}
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type descExporter struct {
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c *collector
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descCh chan<- *prometheus.Desc
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}
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// ExportMetrics exports descriptor to the Prometheus.
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// It is invoked when request to scrape descriptors is received.
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func (me *descExporter) ExportMetrics(ctx context.Context, metrics []*metricdata.Metric) error {
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for _, metric := range metrics {
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desc := me.c.toDesc(metric)
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me.descCh <- desc
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}
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return nil
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}
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func toPromLabels(mls []metricdata.LabelKey) (labels []string) {
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for _, ml := range mls {
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labels = append(labels, sanitize(ml.Key))
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}
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return labels
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}
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func metricName(namespace string, m *metricdata.Metric) string {
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var name string
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if namespace != "" {
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name = namespace + "_"
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}
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return name + sanitize(m.Descriptor.Name)
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}
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func toPromMetric(
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desc *prometheus.Desc,
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metric *metricdata.Metric,
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point metricdata.Point,
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labelValues []string) (prometheus.Metric, error) {
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switch metric.Descriptor.Type {
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case metricdata.TypeCumulativeFloat64, metricdata.TypeCumulativeInt64:
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pv, err := toPromValue(point)
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if err != nil {
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return nil, err
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}
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return prometheus.NewConstMetric(desc, prometheus.CounterValue, pv, labelValues...)
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case metricdata.TypeGaugeFloat64, metricdata.TypeGaugeInt64:
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pv, err := toPromValue(point)
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if err != nil {
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return nil, err
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}
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return prometheus.NewConstMetric(desc, prometheus.GaugeValue, pv, labelValues...)
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case metricdata.TypeCumulativeDistribution:
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switch v := point.Value.(type) {
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case *metricdata.Distribution:
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points := make(map[float64]uint64)
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// Histograms are cumulative in Prometheus.
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// Get cumulative bucket counts.
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cumCount := uint64(0)
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for i, b := range v.BucketOptions.Bounds {
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cumCount += uint64(v.Buckets[i].Count)
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points[b] = cumCount
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}
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return prometheus.NewConstHistogram(desc, uint64(v.Count), v.Sum, points, labelValues...)
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default:
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return nil, typeMismatchError(point)
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}
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case metricdata.TypeSummary:
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// TODO: [rghetia] add support for TypeSummary.
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return nil, nil
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default:
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return nil, fmt.Errorf("aggregation %T is not yet supported", metric.Descriptor.Type)
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}
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}
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func toLabelValues(labelValues []metricdata.LabelValue) (values []string) {
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for _, lv := range labelValues {
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if lv.Present {
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values = append(values, lv.Value)
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} else {
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values = append(values, "")
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}
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}
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return values
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}
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func typeMismatchError(point metricdata.Point) error {
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return fmt.Errorf("point type %T does not match metric type", point)
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}
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func toPromValue(point metricdata.Point) (float64, error) {
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switch v := point.Value.(type) {
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case float64:
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return v, nil
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case int64:
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return float64(v), nil
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default:
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return 0.0, typeMismatchError(point)
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}
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}
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