Add metrics

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/aws/aws-sdk-go-v2/credentials v1.13.35
 	github.com/aws/aws-sdk-go-v2/service/s3 v1.38.5
 	github.com/fxamacker/cbor/v2 v2.5.0
+	github.com/prometheus/client_golang v1.16.0
 	golang.org/x/sync v0.3.0
 )
 
@@ -26,5 +27,14 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.15.5 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sts v1.21.5 // indirect
 	github.com/aws/smithy-go v1.14.2 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/golang/protobuf v1.5.3 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common v0.42.0 // indirect
+	github.com/prometheus/procfs v0.10.1 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
+	golang.org/x/sys v0.8.0 // indirect
+	google.golang.org/protobuf v1.30.0 // indirect
 )

go.sum

@@ -34,18 +34,47 @@ github.com/aws/aws-sdk-go-v2/service/sts v1.21.5 h1:CQBFElb0LS8RojMJlxRSo/HXipvT
 github.com/aws/aws-sdk-go-v2/service/sts v1.21.5/go.mod h1:VC7JDqsqiwXukYEDjoHh9U0fOJtNWh04FPQz4ct4GGU=
 github.com/aws/smithy-go v1.14.2 h1:MJU9hqBGbvWZdApzpvoF2WAIJDbtjK2NDJSiJP7HblQ=
 github.com/aws/smithy-go v1.14.2/go.mod h1:Tg+OJXh4MB2R/uN61Ko2f6hTZwB/ZYGOtib8J3gBHzA=
+github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
+github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/fxamacker/cbor/v2 v2.5.0 h1:oHsG0V/Q6E/wqTS2O1Cozzsy69nqCiguo5Q1a1ADivE=
 github.com/fxamacker/cbor/v2 v2.5.0/go.mod h1:TA1xS00nchWmaBnEIxPSE5oHLuJBAVvqrtAnWBwBCVo=
-github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.5/go.mod h1:6O5/vntMXwX2lRkT1hjjk0nAC1IDOTvTlVgjlRvqsdk=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
+github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/jmespath/go-jmespath v0.4.0/go.mod h1:T8mJZnbsbmF+m6zOOFylbeCJqk5+pHWvzYPziyZiYoo=
 github.com/jmespath/go-jmespath/internal/testify v1.5.1/go.mod h1:L3OGu8Wl2/fWfCI6z80xFu9LTZmf1ZRjMHUOPmWr69U=
+github.com/matttproud/golang_protobuf_extensions v1.0.4 h1:mmDVorXM7PCGKw94cs5zkfA9PSy5pEvNWRP0ET0TIVo=
+github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v1.16.0 h1:yk/hx9hDbrGHovbci4BY+pRMfSuuat626eFsHb7tmT8=
+github.com/prometheus/client_golang v1.16.0/go.mod h1:Zsulrv/L9oM40tJ7T815tM89lFEugiJ9HzIqaAx4LKc=
+github.com/prometheus/client_model v0.3.0 h1:UBgGFHqYdG/TPFD1B1ogZywDqEkwp3fBMvqdiQ7Xew4=
+github.com/prometheus/client_model v0.3.0/go.mod h1:LDGWKZIo7rky3hgvBe+caln+Dr3dPggB5dvjtD7w9+w=
+github.com/prometheus/common v0.42.0 h1:EKsfXEYo4JpWMHH5cg+KOUWeuJSov1Id8zGR8eeI1YM=
+github.com/prometheus/common v0.42.0/go.mod h1:xBwqVerjNdUDjgODMpudtOMwlOwf2SaTr1yjz4b7Zbc=
+github.com/prometheus/procfs v0.10.1 h1:kYK1Va/YMlutzCGazswoHKo//tZVlFpKYh+PymziUAg=
+github.com/prometheus/procfs v0.10.1/go.mod h1:nwNm2aOCAYw8uTR/9bWRREkZFxAUcWzPHWJq+XBB/FM=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcYsOfg=
+golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
 golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
+golang.org/x/sys v0.8.0 h1:EBmGv8NaZBZTWvrbjNoL6HVt+IVy3QDQpJs7VRIw3tU=
+golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

integration_test.go

@@ -23,6 +23,7 @@ import (
 	"github.com/aws/aws-sdk-go-v2/config"
 	"github.com/aws/aws-sdk-go-v2/credentials"
 	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/prometheus/client_golang/prometheus"
 	"golang.org/x/sync/singleflight"
 )
 
@@ -149,6 +150,10 @@ func TestIntegration(t *testing.T) {
 		s3Bucket:  "bucket",
 
 		cacheGroup: &singleflight.Group{},
+
+		requestsMetric:     prometheus.NewCounterVec(prometheus.CounterOpts{}, []string{"result", "source"}),
+		partialTiles:       prometheus.NewCounter(prometheus.CounterOpts{}),
+		singleFlightShared: prometheus.NewCounter(prometheus.CounterOpts{}),
 	}
 
 	// Invalid URL; should 404

main.go

@@ -13,6 +13,7 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -22,6 +23,9 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/s3"
 	"github.com/aws/aws-sdk-go-v2/service/s3/types"
 	"github.com/fxamacker/cbor/v2"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"golang.org/x/sync/singleflight"
 )
 
@@ -237,6 +241,10 @@ type tileCachingHandler struct {
 	s3Bucket  string     // The S3 bucket to use for caching tiles. Must not be empty.
 
 	cacheGroup *singleflight.Group // The singleflight.Group to use for deduplicating simultaneous requests (a.k.a. "request collapsing") for tiles. Must not be nil.
+
+	requestsMetric     *prometheus.CounterVec
+	partialTiles       prometheus.Counter
+	singleFlightShared prometheus.Counter
 }
 
 func (tch *tileCachingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -284,8 +292,9 @@ func (tch *tileCachingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request)
 		//
 		// When Trillian gets a request that is past the end of the log, it returns
 		// 400 (for better or worse), so we emulate that here.
+		tch.requestsMetric.WithLabelValues("error", "ct_log_past_end").Inc()
 		w.WriteHeader(http.StatusBadRequest)
-		w.Write([]byte("requested range is past the end of the log"))
+		fmt.Fprintln(w, "requested range is past the end of the log")
 		return
 	} else {
 		contents.Entries = contents.Entries[prefixToRemove:]
@@ -296,6 +305,12 @@ func (tch *tileCachingHandler) ServeHTTP(w http.ResponseWriter, r *http.Request)
 		contents.Entries = contents.Entries[:requestedLen]
 	}
 
+	if w.Header().Get("X-Source") == "S3" {
+		tch.requestsMetric.WithLabelValues("success", "s3_get").Inc()
+	} else {
+		tch.requestsMetric.WithLabelValues("success", "ct_log_get").Inc()
+	}
+
 	w.Header().Set("X-Response-Len", fmt.Sprintf("%d", len(contents.Entries)))
 	w.WriteHeader(http.StatusOK)
 
@@ -325,11 +340,15 @@ func (tch *tileCachingHandler) getAndCacheTile(ctx context.Context, tile tile) (
 		source  tileSource
 	}
 
-	innerContents, err, _ := singleflightDo(tch.cacheGroup, dedupKey, func() (entriesAndSource, error) {
+	innerContents, err, shared := singleflightDo(tch.cacheGroup, dedupKey, func() (entriesAndSource, error) {
 		contents, source, err := tch.getAndCacheTileUncollapsed(ctx, tile)
 		return entriesAndSource{contents, source}, err
 	})
 
+	if shared {
+		tch.singleFlightShared.Inc()
+	}
+
 	// The value from our singleflightDo closure is always non-nil, so we don't
 	// need an err != nil check here.
 	return innerContents.entries, innerContents.source, err
@@ -344,23 +363,27 @@ func (tch *tileCachingHandler) getAndCacheTileUncollapsed(ctx context.Context, t
 	}
 
 	if !errors.Is(err, noSuchKey{}) {
+		tch.requestsMetric.WithLabelValues("error", "s3_get").Inc()
 		return nil, sourceS3, fmt.Errorf("error reading tile from s3: %w", err)
 	}
 
 	contents, err = getTileFromBackend(ctx, tile)
 	if err != nil {
+		tch.requestsMetric.WithLabelValues("error", "ct_log_get").Inc()
 		return nil, sourceCTLog, fmt.Errorf("error reading tile from backend: %w", err)
 	}
 
 	// If we got a partial tile, assume we are at the end of the log and the last
 	// tile isn't filled up yet. In that case, don't write to S3, but still return
 	// results to the user.
 	if tch.isPartialTile(contents) {
+		tch.partialTiles.Inc()
 		return contents, sourceCTLog, nil
 	}
 
 	err = tch.writeToS3(ctx, tile, contents)
 	if err != nil {
+		tch.requestsMetric.WithLabelValues("error", "s3_put").Inc()
 		return nil, sourceCTLog, fmt.Errorf("error writing tile to S3: %w", err)
 	}
 	return contents, sourceCTLog, nil
@@ -387,7 +410,8 @@ func main() {
 	tileSize := flag.Int("tile-size", 0, "tile size. Must match the value used by the backend")
 	s3bucket := flag.String("s3-bucket", "", "s3 bucket to use for caching")
 	s3prefix := flag.String("s3-prefix", "", "prefix for s3 keys. defaults to value of -backend")
-	listenAddress := flag.String("listen-address", ":8080", "address to listen on")
+	listenAddress := flag.String("listen-address", ":7962", "address to listen on")
+	metricsAddress := flag.String("metrics-address", ":7963", "address to listen on for metrics")
 
 	// fullRequestTimeout is the max allowed time the handler can read from S3 and return or read from S3, read from backend, write to S3, and return.
 	fullRequestTimeout := flag.Duration("full-request-timeout", 4*time.Second, "max time to spend in the HTTP handler")
@@ -420,13 +444,41 @@ func main() {
 	}
 	svc := s3.NewFromConfig(cfg)
 
+	promRegistry := newStatsRegistry(*metricsAddress)
+
+	requestsMetric := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "ctile_requests",
+			Help: "total number of requests, by result and source",
+		},
+		[]string{"result", "source"},
+	)
+	promRegistry.MustRegister(requestsMetric)
+
+	partialTiles := prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "ctile_partial_tiles",
+			Help: "number of requests not cached due to partial tile returned from CT log",
+		})
+	promRegistry.MustRegister(partialTiles)
+
+	singleFlightShared := prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "ctile_single_flight_shared",
+			Help: "number of inbound requests coalesced into a single set of backend requests",
+		})
+	promRegistry.MustRegister(singleFlightShared)
+
 	handler := &tileCachingHandler{
-		logURL:     *logURL,
-		tileSize:   *tileSize,
-		s3Service:  svc,
-		s3Prefix:   *s3prefix,
-		s3Bucket:   *s3bucket,
-		cacheGroup: &singleflight.Group{},
+		logURL:             *logURL,
+		tileSize:           *tileSize,
+		s3Service:          svc,
+		s3Prefix:           *s3prefix,
+		s3Bucket:           *s3bucket,
+		cacheGroup:         &singleflight.Group{},
+		requestsMetric:     requestsMetric,
+		partialTiles:       partialTiles,
+		singleFlightShared: singleFlightShared,
 	}
 
 	srv := http.Server{
@@ -440,3 +492,27 @@ func main() {
 
 	log.Fatal(srv.ListenAndServe())
 }
+
+func newStatsRegistry(listenAddress string) prometheus.Registerer {
+	registry := prometheus.NewRegistry()
+	registry.MustRegister(collectors.NewGoCollector())
+	registry.MustRegister(collectors.NewProcessCollector(
+		collectors.ProcessCollectorOpts{}))
+
+	server := http.Server{
+		Addr:              listenAddress,
+		ReadTimeout:       5 * time.Second,
+		WriteTimeout:      5 * time.Second,
+		IdleTimeout:       5 * time.Minute,
+		ReadHeaderTimeout: 2 * time.Second,
+		Handler:           promhttp.HandlerFor(registry, promhttp.HandlerOpts{}),
+	}
+	go func() {
+		err := server.ListenAndServe()
+		if err != nil {
+			log.Printf("unable to start metrics server on %s: %s\n", listenAddress, err)
+			os.Exit(1)
+		}
+	}()
+	return registry
+}