feat(llard): add Prometheus metrics

cmd/llard/main.go

@@ -21,6 +21,7 @@ import (
 	"github.com/goplus/llar/internal/formula/repo"
 	"github.com/goplus/llar/internal/vcs"
 	"github.com/joho/godotenv"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 type config struct {
@@ -82,17 +83,23 @@ func run() error {
 		WorkspaceDir: workspaceDir,
 		Artifacts:    artifacts,
 	})
-	handler := buildhttp.New(buildhttp.Options{
+	buildHandler := buildhttp.New(buildhttp.Options{
 		FormulaStore: formulaStore,
 		Cache:        buildCache,
 		Artifacts:    artifacts,
 		WorkspaceDir: workspaceDir,
 	})
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", promhttp.Handler())
+	mux.HandleFunc("/health", func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	})
+	mux.Handle("/v1/artifacts/", buildHandler)
 	server := &http.Server{
 		Addr: cfg.addr,
 		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			log.Printf("request method=%s uri=%s remote=%s", r.Method, r.URL.RequestURI(), r.RemoteAddr)
-			handler.ServeHTTP(w, r)
+			mux.ServeHTTP(w, r)
 		}),
 	}
 

go.mod

@@ -11,6 +11,7 @@ require (
 	github.com/joho/godotenv v1.5.1
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51
 	github.com/petermattis/goid v0.0.0-20260713073324-57ed88f34a0a
+	github.com/prometheus/client_golang v1.23.2
 	github.com/qiniu/go-sdk/v7 v7.26.14
 	github.com/qiniu/x v1.16.0
 	github.com/spf13/cobra v1.10.2
@@ -22,6 +23,8 @@ require (
 require (
 	github.com/BurntSushi/toml v1.3.2 // indirect
 	github.com/alex-ant/gomath v0.0.0-20160516115720-89013a210a82 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/containerd/stargz-snapshotter/estargz v0.18.1 // indirect
 	github.com/docker/cli v29.0.3+incompatible // indirect
 	github.com/docker/distribution v2.8.3+incompatible // indirect
@@ -35,8 +38,12 @@ require (
 	github.com/klauspost/compress v1.18.1 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.1.1 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
 	github.com/sirupsen/logrus v1.9.3 // indirect
 	github.com/spf13/pflag v1.0.9 // indirect
 	github.com/timandy/routine v1.1.5 // indirect
@@ -45,7 +52,8 @@ require (
 	github.com/visualfc/gid v0.3.0 // indirect
 	github.com/visualfc/goembed v0.3.2 // indirect
 	github.com/visualfc/xtype v0.2.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
 	golang.org/x/tools v0.40.0 // indirect
-	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
+	google.golang.org/protobuf v1.36.8 // indirect
 	modernc.org/fileutil v1.0.0 // indirect
 )

go.sum

@@ -2,6 +2,10 @@ github.com/BurntSushi/toml v1.3.2 h1:o7IhLm0Msx3BaB+n3Ag7L8EVlByGnpq14C4YWiu/gL8
 github.com/BurntSushi/toml v1.3.2/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbicEuybxQ=
 github.com/alex-ant/gomath v0.0.0-20160516115720-89013a210a82 h1:7dONQ3WNZ1zy960TmkxJPuwoolZwL7xKtpcM04MBnt4=
 github.com/alex-ant/gomath v0.0.0-20160516115720-89013a210a82/go.mod h1:nLnM0KdK1CmygvjpDUO6m1TjSsiQtL61juhNsvV/JVI=
+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 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
+github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/containerd/stargz-snapshotter/estargz v0.18.1 h1:cy2/lpgBXDA3cDKSyEfNOFMA/c10O1axL69EU7iirO8=
 github.com/containerd/stargz-snapshotter/estargz v0.18.1/go.mod h1:ALIEqa7B6oVDsrF37GkGN20SuvG/pIMm7FwP7ZmRb0Q=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
@@ -48,15 +52,16 @@ github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNU
 github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/klauspost/compress v1.18.1 h1:bcSGx7UbpBqMChDtsF28Lw6v/G94LPrrbMbdC3JH2co=
 github.com/klauspost/compress v1.18.1/go.mod h1:ZQFFVG+MdnR0P+l6wpXgIL4NTtwiKIdBnrBd8Nrxr+0=
-github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
-github.com/kr/pretty v0.3.0 h1:WgNl7dwNpEZ6jJ9k1snq4pZsg7DOEN8hP9Xw0Tsjwk0=
-github.com/kr/pretty v0.3.0/go.mod h1:640gp4NfQd8pI5XOwp5fnNeVWj67G7CFk/SaSQn7NBk=
-github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
+github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8Oi/yOhh5U=
 github.com/opencontainers/go-digest v1.0.0/go.mod h1:0JzlMkj0TRzQZfJkVvzbP0HBR3IKzErnv2BNG4W4MAM=
 github.com/opencontainers/image-spec v1.1.1 h1:y0fUlFfIZhPF1W537XOLg0/fcx6zcHCJwooC2xJA040=
@@ -67,12 +72,20 @@ github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prometheus/client_golang v1.23.2 h1:Je96obch5RDVy3FDMndoUsjAhG5Edi49h0RJWRi/o0o=
+github.com/prometheus/client_golang v1.23.2/go.mod h1:Tb1a6LWHB3/SPIzCoaDXI4I8UHKeFTEQ1YCr+0Gyqmg=
+github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
+github.com/prometheus/client_model v0.6.2/go.mod h1:y3m2F6Gdpfy6Ut/GBsUqTWZqCUvMVzSfMLjcu6wAwpE=
+github.com/prometheus/common v0.66.1 h1:h5E0h5/Y8niHc5DlaLlWLArTQI7tMrsfQjHV+d9ZoGs=
+github.com/prometheus/common v0.66.1/go.mod h1:gcaUsgf3KfRSwHY4dIMXLPV0K/Wg1oZ8+SbZk/HH/dA=
+github.com/prometheus/procfs v0.16.1 h1:hZ15bTNuirocR6u0JZ6BAHHmwS1p8B4P6MRqxtzMyRg=
+github.com/prometheus/procfs v0.16.1/go.mod h1:teAbpZRB1iIAJYREa1LsoWUXykVXA1KlTmWl8x/U+Is=
 github.com/qiniu/go-sdk/v7 v7.26.14 h1:kV9zdvTOM0w9/lgeYffDDw0Fj8FH14/XgCjk4Wb80k8=
 github.com/qiniu/go-sdk/v7 v7.26.14/go.mod h1:ri7fGwbio0pRDFr8EK5TUpx0DbnpIMJ2bMSDxGWfCbk=
 github.com/qiniu/x v1.16.0 h1:W2VOecyIT3Uxwjm6vJinUR7G3gpwgUgHZA9OpeHArdE=
 github.com/qiniu/x v1.16.0/go.mod h1:AiovSOCaRijaf3fj+0CBOpR1457pn24b0Vdb1JpwhII=
-github.com/rogpeppe/go-internal v1.8.0 h1:FCbCCtXNOY3UtUuHUYaghJg4y7Fd14rXifAYUAtL9R8=
-github.com/rogpeppe/go-internal v1.8.0/go.mod h1:WmiCO8CzOY8rg0OYDC4/i/2WRWAB6poM+XZ2dLUbcbE=
+github.com/rogpeppe/go-internal v1.10.0 h1:TMyTOH3F/DB16zRVcYyreMH6GnZZrwQVAoYjRBZyWFQ=
+github.com/rogpeppe/go-internal v1.10.0/go.mod h1:UQnix2H7Ngw/k4C5ijL5+65zddjncjaFoBhdsK/akog=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
 github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
@@ -88,8 +101,9 @@ github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/timandy/routine v1.1.5 h1:LSpm7Iijwb9imIPlucl4krpr2EeCeAUvifiQ9Uf5X+M=
 github.com/timandy/routine v1.1.5/go.mod h1:kXslgIosdY8LW0byTyPnenDgn4/azt2euufAq9rK51w=
 github.com/vbatts/tar-split v0.12.2 h1:w/Y6tjxpeiFMR47yzZPlPj/FcPLpXbTUi/9H7d3CPa4=
@@ -102,6 +116,10 @@ github.com/visualfc/goembed v0.3.2 h1:a9m6o9VTzNk3mEF98C8cHp8f8P8BblyjsjajXGfTp8
 github.com/visualfc/goembed v0.3.2/go.mod h1:jCVCz/yTJGyslo6Hta+pYxWWBuq9ADCcIVZBTQ0/iVI=
 github.com/visualfc/xtype v0.2.0 h1:0ESNXyWHtK01kaOzOyqHsR1ZjEPdNu/IWPZkf0VOHl8=
 github.com/visualfc/xtype v0.2.0/go.mod h1:183MDtzLqyDkCm5zCH42vJGq/aQE5W25k3Z6UOZxLF0=
+go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
+go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
+go.yaml.in/yaml/v2 v2.4.2 h1:DzmwEr2rDGHl7lsFgAHxmNz/1NlQ7xLIrlN2h5d1eGI=
+go.yaml.in/yaml/v2 v2.4.2/go.mod h1:081UH+NErpNdqlCXm3TtEran0rJZGxAYx9hb/ELlsPU=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
 golang.org/x/mod v0.32.0 h1:9F4d3PHLljb6x//jOyokMv3eX+YDeepZSEo3mFJy93c=
 golang.org/x/mod v0.32.0/go.mod h1:SgipZ/3h2Ci89DlEtEXWUk/HteuRin+HHhN+WbNhguU=
@@ -112,6 +130,8 @@ golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
 golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/tools v0.40.0 h1:yLkxfA+Qnul4cs9QA3KnlFu0lVmd8JJfoq+E41uSutA=
 golang.org/x/tools v0.40.0/go.mod h1:Ik/tzLRlbscWpqqMRjyWYDisX8bG13FrdXp3o4Sr9lc=
+google.golang.org/protobuf v1.36.8 h1:xHScyCOEuuwZEc6UtSOvPbAT4zRh0xcNRYekJwfqyMc=
+google.golang.org/protobuf v1.36.8/go.mod h1:fuxRtAxBytpl4zzqUh6/eyUujkJdNiuEkXntxiD/uRU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

internal/build/build.go

@@ -10,11 +10,13 @@ import (
 	"path/filepath"
 	"sort"
 	"strings"
+	"time"
 
 	classfile "github.com/goplus/llar/formula"
 	"github.com/goplus/llar/internal/build/cache"
 	"github.com/goplus/llar/internal/execbroker"
 	"github.com/goplus/llar/internal/formula/repo"
+	"github.com/goplus/llar/internal/metrics"
 	"github.com/goplus/llar/internal/modules"
 	"github.com/goplus/llar/internal/vcs"
 	"github.com/goplus/llar/mod/module"
@@ -239,14 +241,22 @@ func (b *Builder) Build(ctx context.Context, targets []*modules.Module) ([]Resul
 		}
 		deps := b.resolveModTransitiveDeps(targets, mod)
 		modVer := module.Version{Path: mod.Path, Version: mod.Version}
+		cacheTarget := fmt.Sprintf("%s@%s?matrix=%s", mod.Path, mod.Version, b.matrix)
 
 		// Consult the build cache. A hit means we already have the
 		// module's build metadata and its installDir is populated from a
 		// previous successful build.
 		entry, cacheHit, err := b.cache.Get(ctx, cache.Key{Module: modVer, Matrix: b.matrix})
 		if err != nil {
+			metrics.BuildCacheLookups.WithLabelValues(cacheTarget, "error").Inc()
+			metrics.BuildFailures.WithLabelValues("cache_get").Inc()
 			return Result{}, err
 		}
+		if cacheHit {
+			metrics.BuildCacheLookups.WithLabelValues(cacheTarget, "hit").Inc()
+		} else {
+			metrics.BuildCacheLookups.WithLabelValues(cacheTarget, "miss").Inc()
+		}
 
 		// Fast path: cache hit and no OnTest to run. Skip source clone
 		// and OnBuild entirely.
@@ -269,9 +279,11 @@ func (b *Builder) Build(ctx context.Context, targets []*modules.Module) ([]Resul
 		// TODO(MeteorsLiu): Support different code host
 		repo, err := b.newRepo(fmt.Sprintf("github.com/%s", mod.Path))
 		if err != nil {
+			metrics.BuildFailures.WithLabelValues("source_sync").Inc()
 			return Result{}, err
 		}
 		if err := repo.Sync(ctx, mod.Version, "", tmpSourceDir); err != nil {
+			metrics.BuildFailures.WithLabelValues("source_sync").Inc()
 			return Result{}, err
 		}
 
@@ -305,6 +317,7 @@ func (b *Builder) Build(ctx context.Context, targets []*modules.Module) ([]Resul
 				var out classfile.BuildResult
 				mod.OnBuild(buildContext, project, &out)
 				if len(out.Errs()) > 0 {
+					metrics.BuildFailures.WithLabelValues("on_build").Inc()
 					return errors.Join(out.Errs()...)
 				}
 				metadata = out.Metadata()
@@ -333,6 +346,7 @@ func (b *Builder) Build(ctx context.Context, targets []*modules.Module) ([]Resul
 				Deps:     deps,
 			})
 			if err != nil {
+				metrics.BuildFailures.WithLabelValues("cache_put").Inc()
 				return Result{}, err
 			}
 			metadata = entry.Metadata
@@ -369,8 +383,13 @@ func (b *Builder) Build(ctx context.Context, targets []*modules.Module) ([]Resul
 	sort.Strings(lockPaths)
 	unlocks := make([]func(), 0, len(lockPaths))
 	for _, path := range lockPaths {
+		started := time.Now()
+		metrics.BuildLockWaiters.WithLabelValues(path).Inc()
 		unlock, err := b.store.LockModule(path)
+		metrics.BuildLockWaiters.WithLabelValues(path).Dec()
+		metrics.BuildLockWaitDuration.Observe(time.Since(started).Seconds())
 		if err != nil {
+			metrics.BuildFailures.WithLabelValues("lock").Inc()
 			for i := len(unlocks) - 1; i >= 0; i-- {
 				unlocks[i]()
 			}

internal/build/http/http.go

@@ -8,18 +8,21 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/goplus/llar/formula"
 	"github.com/goplus/llar/internal/artifact"
 	"github.com/goplus/llar/internal/build"
 	"github.com/goplus/llar/internal/build/cache"
 	"github.com/goplus/llar/internal/formula/repo"
+	"github.com/goplus/llar/internal/metrics"
 	"github.com/goplus/llar/internal/modules"
 	"github.com/goplus/llar/mod/module"
 	"golang.org/x/sync/singleflight"
@@ -72,15 +75,26 @@ func New(opts Options) http.Handler {
 }
 
 func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	started := time.Now()
+	outcome := "success"
+	metrics.RequestsInFlight.Inc()
+	defer func() {
+		metrics.RequestsInFlight.Dec()
+		metrics.RequestsTotal.WithLabelValues(outcome).Inc()
+		metrics.RequestDuration.WithLabelValues(outcome).Observe(time.Since(started).Seconds())
+	}()
+
 	w.Header().Set("Content-Type", "application/x-cmdjsonl")
 	if r.Method != http.MethodGet {
+		outcome = "client_error"
 		w.Header().Set("Allow", http.MethodGet)
 		writeCommand(w, "error", "method not allowed")
 		return
 	}
 
 	req, err := parseRequest(r)
 	if err != nil {
+		outcome = "client_error"
 		writeCommand(w, "error", err.Error())
 		return
 	}
@@ -89,6 +103,10 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	result, err := h.do(r.Context(), req, info)
 	info.flush()
 	if err != nil {
+		outcome = "server_error"
+		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+			outcome = "canceled"
+		}
 		writeCommand(w, "error", err.Error())
 		return
 	}
@@ -99,14 +117,29 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 func (h *handler) do(ctx context.Context, req request, info io.Writer) (result, error) {
 	key := requestKey(req)
-	stream, _ := h.infos.LoadOrStore(key, newFanout())
+	stream, shared := h.infos.LoadOrStore(key, newFanout())
+	if shared {
+		metrics.BuildSharedRequests.Inc()
+	}
 	fanout := stream.(*fanout)
 	remove := fanout.add(info)
 	defer remove()
 
 	call := h.group.DoChan(key, func() (any, error) {
+		started := time.Now()
+		outcome := "success"
+		metrics.BuildsInProgress.WithLabelValues(key).Inc()
+		defer func() {
+			metrics.BuildsInProgress.WithLabelValues(key).Dec()
+			metrics.BuildsTotal.WithLabelValues(outcome).Inc()
+			metrics.BuildDuration.WithLabelValues(outcome).Observe(time.Since(started).Seconds())
+		}()
 		defer h.infos.Delete(key)
-		return h.build(context.WithoutCancel(ctx), req, fanout)
+		result, err := h.build(context.WithoutCancel(ctx), req, fanout)
+		if err != nil {
+			outcome = "server_error"
+		}
+		return result, err
 	})
 	select {
 	case <-ctx.Done():
@@ -125,6 +158,7 @@ func (h *handler) build(ctx context.Context, req request, info io.Writer) (resul
 		Matrix:       req.matrix,
 	})
 	if err != nil {
+		metrics.BuildFailures.WithLabelValues("resolve").Inc()
 		return result{}, err
 	}
 
@@ -153,6 +187,7 @@ func (h *handler) build(ctx context.Context, req request, info io.Writer) (resul
 			MatrixStr: req.matrixStr,
 		})
 		if err != nil {
+			metrics.BuildFailures.WithLabelValues("artifact_get").Inc()
 			return result{}, err
 		}
 		item := artifactMessage{