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web: add basic federation support.
This commit adds a federation handler on /federate. It accepts `match[]` query parameters containing vector selectors. Their intersection determines the in-memory metrics that are returned in the same way as the /metrics endpoint does (modulo sorting).
This commit is contained in:
parent
dc7d27ab9a
commit
39a8254963
108
web/federate.go
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108
web/federate.go
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package web
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import (
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"io"
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"net/http"
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"bitbucket.org/ww/goautoneg"
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"github.com/golang/protobuf/proto"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/text"
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"github.com/prometheus/prometheus/promql"
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"github.com/prometheus/prometheus/storage/local"
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clientmodel "github.com/prometheus/client_golang/model"
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dto "github.com/prometheus/client_model/go"
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)
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type Federation struct {
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Storage local.Storage
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}
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func (fed *Federation) ServeHTTP(w http.ResponseWriter, req *http.Request) {
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req.ParseForm()
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metrics := map[clientmodel.Fingerprint]clientmodel.COWMetric{}
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for _, s := range req.Form["match[]"] {
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matchers, err := promql.ParseMetricSelector(s)
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if err != nil {
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http.Error(w, err.Error(), http.StatusBadRequest)
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return
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}
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for fp, met := range fed.Storage.MetricsForLabelMatchers(matchers...) {
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metrics[fp] = met
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}
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}
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enc, contentType := chooseEncoder(req)
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w.Header().Set("Content-Type", contentType)
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protMetric := &dto.Metric{
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Label: []*dto.LabelPair{},
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Untyped: &dto.Untyped{},
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}
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protMetricFam := &dto.MetricFamily{
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Metric: []*dto.Metric{protMetric},
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Type: dto.MetricType_UNTYPED.Enum(),
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}
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for fp, met := range metrics {
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sp := fed.Storage.LastSamplePairForFingerprint(fp)
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if sp == nil {
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continue
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}
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// Reset label slice.
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protMetric.Label = protMetric.Label[:0]
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for ln, lv := range met.Metric {
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if ln == clientmodel.MetricNameLabel {
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protMetricFam.Name = proto.String(string(lv))
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continue
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}
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protMetric.Label = append(protMetric.Label, &dto.LabelPair{
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Name: proto.String(string(ln)),
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Value: proto.String(string(lv)),
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})
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}
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protMetric.TimestampMs = (*int64)(&sp.Timestamp)
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protMetric.Untyped.Value = (*float64)(&sp.Value)
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if _, err := enc(w, protMetricFam); err != nil {
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http.Error(w, err.Error(), http.StatusInternalServerError)
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return
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}
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}
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}
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type encoder func(w io.Writer, p *dto.MetricFamily) (int, error)
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func chooseEncoder(req *http.Request) (encoder, string) {
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accepts := goautoneg.ParseAccept(req.Header.Get("Accept"))
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for _, accept := range accepts {
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switch {
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case accept.Type == "application" &&
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accept.SubType == "vnd.google.protobuf" &&
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accept.Params["proto"] == "io.prometheus.client.MetricFamily":
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switch accept.Params["encoding"] {
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case "delimited":
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return text.WriteProtoDelimited, prometheus.DelimitedTelemetryContentType
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case "text":
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return text.WriteProtoText, prometheus.ProtoTextTelemetryContentType
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case "compact-text":
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return text.WriteProtoCompactText, prometheus.ProtoCompactTextTelemetryContentType
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default:
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continue
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}
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case accept.Type == "text" &&
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accept.SubType == "plain" &&
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(accept.Params["version"] == "0.0.4" || accept.Params["version"] == ""):
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return text.MetricFamilyToText, prometheus.TextTelemetryContentType
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default:
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continue
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}
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}
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return text.MetricFamilyToText, prometheus.TextTelemetryContentType
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}
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@ -54,8 +54,9 @@ type Handler struct {
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ruleManager *rules.Manager
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queryEngine *promql.Engine
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apiV1 *v1.API
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apiLegacy *legacy.API
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apiV1 *v1.API
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apiLegacy *legacy.API
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federation *Federation
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router *route.Router
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quitCh chan struct{}
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@ -125,6 +126,9 @@ func New(st local.Storage, qe *promql.Engine, rm *rules.Manager, status *Prometh
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Storage: st,
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Now: clientmodel.Now,
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},
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federation: &Federation{
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Storage: st,
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},
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}
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if o.PathPrefix != "" {
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@ -145,6 +149,7 @@ func New(st local.Storage, qe *promql.Engine, rm *rules.Manager, status *Prometh
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router.Get("/heap", instrf("heap", dumpHeap))
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router.Get("/federate", instrh("federate", h.federation))
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router.Get(o.MetricsPath, prometheus.Handler().ServeHTTP)
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h.apiLegacy.Register(router.WithPrefix("/api"))
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