/
proxy.go
247 lines (207 loc) · 6.6 KB
/
proxy.go
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// Copyright (c) The Thanos Authors.
// Licensed under the Apache License 2.0.
package exemplars
import (
"context"
"io"
"strings"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/pkg/errors"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/promql/parser"
"golang.org/x/sync/errgroup"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/status"
"github.com/thanos-io/thanos/pkg/exemplars/exemplarspb"
"github.com/thanos-io/thanos/pkg/extpromql"
"github.com/thanos-io/thanos/pkg/store"
"github.com/thanos-io/thanos/pkg/store/storepb"
"github.com/thanos-io/thanos/pkg/tracing"
)
// Proxy implements exemplarspb.Exemplars gRPC that fanouts requests to
// given exemplarspb.Exemplars.
type Proxy struct {
logger log.Logger
exemplars func() []*exemplarspb.ExemplarStore
selectorLabels labels.Labels
}
// RegisterExemplarsServer register exemplars server.
func RegisterExemplarsServer(exemplarsSrv exemplarspb.ExemplarsServer) func(*grpc.Server) {
return func(s *grpc.Server) {
exemplarspb.RegisterExemplarsServer(s, exemplarsSrv)
}
}
// NewProxy return new exemplars.Proxy.
func NewProxy(logger log.Logger, exemplars func() []*exemplarspb.ExemplarStore, selectorLabels labels.Labels) *Proxy {
return &Proxy{
logger: logger,
exemplars: exemplars,
selectorLabels: selectorLabels,
}
}
type exemplarsStream struct {
client exemplarspb.ExemplarsClient
request *exemplarspb.ExemplarsRequest
channel chan<- *exemplarspb.ExemplarData
server exemplarspb.Exemplars_ExemplarsServer
}
func (s *Proxy) Exemplars(req *exemplarspb.ExemplarsRequest, srv exemplarspb.Exemplars_ExemplarsServer) error {
span, ctx := tracing.StartSpan(srv.Context(), "proxy_exemplars")
defer span.Finish()
expr, err := extpromql.ParseExpr(req.Query)
if err != nil {
return err
}
match, selectors := selectorsMatchesExternalLabels(parser.ExtractSelectors(expr), s.selectorLabels)
// There is no matched selectors for this thanos query.
if !match {
return nil
}
if len(selectors) == 0 {
return status.Error(codes.InvalidArgument, errors.New("no matchers specified (excluding external labels)").Error())
}
var (
g, gctx = errgroup.WithContext(ctx)
respChan = make(chan *exemplarspb.ExemplarData, 10)
exemplars []*exemplarspb.ExemplarData
)
queryParts := make([]string, 0)
labelMatchers := make([]string, 0)
for _, st := range s.exemplars() {
queryParts = queryParts[:0]
for _, matcherSet := range selectors {
extLbls := st.LabelSets
if !store.LabelSetsMatch(matcherSet, extLbls...) {
continue
}
labelMatchers = labelMatchers[:0]
for _, m := range matcherSet {
if containsLabelName(m.Name, extLbls) {
// If the current matcher matches one external label,
// we don't add it to the current metric selector
// as Prometheus' Exemplars API cannot handle external labels.
continue
}
labelMatchers = append(labelMatchers, m.String())
}
queryParts = append(queryParts, "{"+strings.Join(labelMatchers, ", ")+"}")
}
// No matchers match this store.
if len(queryParts) == 0 {
continue
}
// Construct the query by concatenating metric selectors with '+'.
// We cannot preserve the original query info, but the returned
// results are the same.
query := strings.Join(queryParts, "+")
r := &exemplarspb.ExemplarsRequest{
Start: req.Start,
End: req.End,
Query: query,
PartialResponseStrategy: req.PartialResponseStrategy,
}
es := &exemplarsStream{
client: st.ExemplarsClient,
request: r,
channel: respChan,
server: srv,
}
g.Go(func() error { return es.receive(gctx) })
}
go func() {
_ = g.Wait()
close(respChan)
}()
for resp := range respChan {
exemplars = append(exemplars, resp)
}
if err := g.Wait(); err != nil {
level.Error(s.logger).Log("err", err)
return err
}
for _, e := range exemplars {
tracing.DoInSpan(srv.Context(), "send_exemplars_response", func(_ context.Context) {
err = srv.Send(exemplarspb.NewExemplarsResponse(e))
})
if err != nil {
return status.Error(codes.Unknown, errors.Wrap(err, "send exemplars response").Error())
}
}
return nil
}
func containsLabelName(name string, sets []labels.Labels) bool {
for _, ls := range sets {
if ls.Get(name) != "" {
return true
}
}
return false
}
func (stream *exemplarsStream) receive(ctx context.Context) error {
exemplars, err := stream.client.Exemplars(ctx, stream.request)
if err != nil {
err = errors.Wrapf(err, "fetching exemplars from exemplars client %v", stream.client)
if stream.request.PartialResponseStrategy == storepb.PartialResponseStrategy_ABORT {
return err
}
if serr := stream.server.Send(exemplarspb.NewWarningExemplarsResponse(err)); serr != nil {
return serr
}
// Not an error if response strategy is warning.
return nil
}
for {
exemplar, err := exemplars.Recv()
if err == io.EOF {
return nil
}
if err != nil {
err = errors.Wrapf(err, "receiving exemplars from exemplars client %v", stream.client)
if stream.request.PartialResponseStrategy == storepb.PartialResponseStrategy_ABORT {
return err
}
if err := stream.server.Send(exemplarspb.NewWarningExemplarsResponse(err)); err != nil {
return errors.Wrapf(err, "sending exemplars error to server %v", stream.server)
}
// Not an error if response strategy is warning.
return nil
}
if w := exemplar.GetWarning(); w != "" {
if err := stream.server.Send(exemplarspb.NewWarningExemplarsResponse(errors.New(w))); err != nil {
return errors.Wrapf(err, "sending exemplars warning to server %v", stream.server)
}
continue
}
select {
case stream.channel <- exemplar.GetData():
case <-ctx.Done():
return ctx.Err()
}
}
}
// matchesExternalLabels returns false if given matchers are not matching external labels.
// If true, matchesExternalLabels also returns Prometheus matchers without those matching external labels.
func matchesExternalLabels(ms []*labels.Matcher, externalLabels labels.Labels) (bool, []*labels.Matcher) {
if externalLabels.IsEmpty() {
return true, ms
}
var newMatchers []*labels.Matcher
for i, tm := range ms {
// Validate all matchers.
extValue := externalLabels.Get(tm.Name)
if extValue == "" {
// Agnostic to external labels.
ms = append(ms[:i], ms[i:]...)
newMatchers = append(newMatchers, tm)
continue
}
if !tm.Matches(extValue) {
// External label does not match. This should not happen - it should be filtered out on query node,
// but let's do that anyway here.
return false, nil
}
}
return true, newMatchers
}