add ExposeLag option, to be able to disable lag exporting

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

README.md

@@ -1,2 +1,2 @@
 # micro-broker-kgo
-![Coverage](https://img.shields.io/badge/Coverage-63.1%25-yellow)
+![Coverage](https://img.shields.io/badge/Coverage-66.9%25-yellow)

go.mod

@@ -1,15 +1,15 @@
 module go.unistack.org/micro-broker-kgo/v4
 
-go 1.23.8
+go 1.24.0
 
 require (
-	github.com/stretchr/testify v1.10.0
+	github.com/stretchr/testify v1.11.1
 	github.com/twmb/franz-go v1.19.5
-	github.com/twmb/franz-go/pkg/kadm v1.16.0
+	github.com/twmb/franz-go/pkg/kadm v1.16.1
 	github.com/twmb/franz-go/pkg/kfake v0.0.0-20250508175730-72e1646135e3
 	github.com/twmb/franz-go/pkg/kmsg v1.11.2
-	go.opentelemetry.io/otel v1.36.0
+	go.opentelemetry.io/otel v1.38.0
-	go.unistack.org/micro/v4 v4.1.17
+	go.unistack.org/micro/v4 v4.1.21
 )
 
 require (
@@ -19,9 +19,9 @@ require (
 	github.com/matoous/go-nanoid v1.5.1 // indirect
 	github.com/pierrec/lz4/v4 v4.1.22 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/spf13/cast v1.9.2 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
 	go.unistack.org/micro-proto/v4 v4.1.0 // indirect
-	golang.org/x/crypto v0.39.0 // indirect
+	golang.org/x/crypto v0.43.0 // indirect
-	google.golang.org/protobuf v1.36.6 // indirect
+	google.golang.org/protobuf v1.36.10 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -20,28 +20,28 @@ github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRI
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR38lUII=
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
-github.com/spf13/cast v1.9.2 h1:SsGfm7M8QOFtEzumm7UZrZdLLquNdzFYfIbEXntcFbE=
+github.com/spf13/cast v1.10.0 h1:h2x0u2shc1QuLHfxi+cTJvs30+ZAHOGRic8uyGTDWxY=
-github.com/spf13/cast v1.9.2/go.mod h1:jNfB8QC9IA6ZuY2ZjDp0KtFO2LZZlg4S/7bzP6qqeHo=
+github.com/spf13/cast v1.10.0/go.mod h1:jNfB8QC9IA6ZuY2ZjDp0KtFO2LZZlg4S/7bzP6qqeHo=
-github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
-github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/twmb/franz-go v1.19.5 h1:W7+o8D0RsQsedqib71OVlLeZ0zI6CbFra7yTYhZTs5Y=
 github.com/twmb/franz-go v1.19.5/go.mod h1:4kFJ5tmbbl7asgwAGVuyG1ZMx0NNpYk7EqflvWfPCpM=
-github.com/twmb/franz-go/pkg/kadm v1.16.0 h1:STMs1t5lYR5mR974PSiwNzE5TvsosByTp+rKXLOhAjE=
+github.com/twmb/franz-go/pkg/kadm v1.16.1 h1:IEkrhTljgLHJ0/hT/InhXGjPdmWfFvxp7o/MR7vJ8cw=
-github.com/twmb/franz-go/pkg/kadm v1.16.0/go.mod h1:MUdcUtnf9ph4SFBLLA/XxE29rvLhWYLM9Ygb8dfSCvw=
+github.com/twmb/franz-go/pkg/kadm v1.16.1/go.mod h1:Ue/ye1cc9ipsQFg7udFbbGiFNzQMqiH73fGC2y0rwyc=
 github.com/twmb/franz-go/pkg/kfake v0.0.0-20250508175730-72e1646135e3 h1:p24opKWPySAy8xSl8NqRgOv7Q+bX7kdrQirBVRJzQfo=
 github.com/twmb/franz-go/pkg/kfake v0.0.0-20250508175730-72e1646135e3/go.mod h1:7uQs3Ae6HkWT1Y9elMbqtAcNFCI0y6+iS+Phw49L49U=
 github.com/twmb/franz-go/pkg/kmsg v1.11.2 h1:hIw75FpwcAjgeyfIGFqivAvwC5uNIOWRGvQgZhH4mhg=
 github.com/twmb/franz-go/pkg/kmsg v1.11.2/go.mod h1:CFfkkLysDNmukPYhGzuUcDtf46gQSqCZHMW1T4Z+wDE=
-go.opentelemetry.io/otel v1.36.0 h1:UumtzIklRBY6cI/lllNZlALOF5nNIzJVb16APdvgTXg=
+go.opentelemetry.io/otel v1.38.0 h1:RkfdswUDRimDg0m2Az18RKOsnI8UDzppJAtj01/Ymk8=
-go.opentelemetry.io/otel v1.36.0/go.mod h1:/TcFMXYjyRNh8khOAO9ybYkqaDBb/70aVwkNML4pP8E=
+go.opentelemetry.io/otel v1.38.0/go.mod h1:zcmtmQ1+YmQM9wrNsTGV/q/uyusom3P8RxwExxkZhjM=
 go.unistack.org/micro-proto/v4 v4.1.0 h1:qPwL2n/oqh9RE3RTTDgt28XK3QzV597VugQPaw9lKUk=
 go.unistack.org/micro-proto/v4 v4.1.0/go.mod h1:ArmK7o+uFvxSY3dbJhKBBX4Pm1rhWdLEFf3LxBrMtec=
-go.unistack.org/micro/v4 v4.1.17 h1:26QDtRSYVpozYuassyvLP4sEQRo3dxgD3sVILRXmIPo=
+go.unistack.org/micro/v4 v4.1.21 h1:F9PrbI1BhXSDS0FopwcO5wWrT2Xh38w9VhVZZBHjfg8=
-go.unistack.org/micro/v4 v4.1.17/go.mod h1:xleO2M5Yxh4s6I+RUcLrEpUjobefh+71ctrdIfn7TUs=
+go.unistack.org/micro/v4 v4.1.21/go.mod h1:nlBXTbx0rQrSZX4HPp2m57PHmpuGPWUd0O+jpUIiPto=
-golang.org/x/crypto v0.39.0 h1:SHs+kF4LP+f+p14esP5jAoDpHU8Gu/v9lFRK6IT5imM=
+golang.org/x/crypto v0.43.0 h1:dduJYIi3A3KOfdGOHX8AVZ/jGiyPa3IbBozJ5kNuE04=
-golang.org/x/crypto v0.39.0/go.mod h1:L+Xg3Wf6HoL4Bn4238Z6ft6KfEpN0tJGo53AAPC632U=
+golang.org/x/crypto v0.43.0/go.mod h1:BFbav4mRNlXJL4wNeejLpWxB7wMbc79PdRGhWKncxR0=
-google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
+google.golang.org/protobuf v1.36.10 h1:AYd7cD/uASjIL6Q9LiTjz8JLcrh/88q5UObnmY3aOOE=
-google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
+google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 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=

kgo.go

@@ -6,11 +6,13 @@ import (
 	"errors"
 	"fmt"
 	"math/rand/v2"
+	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
 
+	"github.com/twmb/franz-go/pkg/kadm"
 	"github.com/twmb/franz-go/pkg/kgo"
 	"github.com/twmb/franz-go/pkg/kmsg"
 	"go.unistack.org/micro/v4/broker"
@@ -245,6 +247,68 @@ func (k *Broker) Connect(ctx context.Context) error {
 	k.connected.Store(1)
 	k.mu.Unlock()
 
+	exposeLag := false
+	if k.opts.Context != nil {
+		if v, ok := k.opts.Context.Value(exposeLagKey{}).(bool); ok && v {
+			exposeLag = v
+		}
+	}
+
+	if exposeLag {
+		var mu sync.Mutex
+		var lastUpdate time.Time
+		type pl struct {
+			p string
+			l float64
+		}
+
+		lag := make(map[string]map[string]pl) // topic => group => partition => lag
+		ac := kadm.NewClient(k.c)
+
+		updateStats := func() {
+			mu.Lock()
+			if time.Since(lastUpdate) < DefaultStatsInterval {
+				return
+			}
+			mu.Unlock()
+
+			k.mu.Lock()
+			groups := make([]string, 0, len(k.subs))
+			for _, g := range k.subs {
+				groups = append(groups, g.opts.Group)
+			}
+			k.mu.Unlock()
+
+			dgls, err := ac.Lag(ctx, groups...)
+			if err != nil || !dgls.Ok() {
+				k.opts.Logger.Error(k.opts.Context, "kgo describe group lag error", err)
+				return
+			}
+
+			for gn, dgl := range dgls {
+				for tn, lmap := range dgl.Lag {
+					if _, ok := lag[tn]; !ok {
+						lag[tn] = make(map[string]pl)
+					}
+					for p, l := range lmap {
+						lag[tn][gn] = pl{p: strconv.Itoa(int(p)), l: float64(l.Lag)}
+					}
+				}
+			}
+		}
+
+		for tn, dg := range lag {
+			for gn, gl := range dg {
+				k.opts.Meter.Gauge(semconv.BrokerGroupLag,
+					func() float64 { updateStats(); return gl.l },
+					"topic", tn,
+					"group", gn,
+					"partition", gl.p)
+			}
+		}
+
+	}
+
 	return nil
 }
 

options.go

@@ -14,7 +14,7 @@ var (
 	DefaultCommitInterval = 5 * time.Second
 
 	// DefaultStatsInterval specifies how fast check consumer lag
-	DefaultStatsInterval = 5 * time.Second
+	DefaultStatsInterval = 30 * time.Second
 
 	// DefaultSubscribeMaxInflight specifies how much messages keep inflight
 	DefaultSubscribeMaxInflight = 100
@@ -116,3 +116,10 @@ type subscribeMessagePoolKey struct{}
 func SubscribeMessagePool(b bool) broker.SubscribeOption {
 	return broker.SetSubscribeOption(subscribeMessagePoolKey{}, b)
 }
+
+type exposeLagKey struct{}
+
+// ExposeLag enabled subscriber lag via [meter.Meter]
+func ExposeLag(b bool) broker.Option {
+	return broker.SetOption(exposeLagKey{}, b)
+}

subscriber.go

@@ -8,7 +8,6 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/twmb/franz-go/pkg/kadm"
 	"github.com/twmb/franz-go/pkg/kgo"
 	"github.com/twmb/franz-go/pkg/kmsg"
 	"go.unistack.org/micro/v4/broker"
@@ -87,46 +86,13 @@ func (s *Subscriber) Unsubscribe(ctx context.Context) error {
 
 func (s *Subscriber) poll(ctx context.Context) {
 	maxInflight := DefaultSubscribeMaxInflight
+
 	if s.opts.Context != nil {
 		if n, ok := s.opts.Context.Value(subscribeMaxInflightKey{}).(int); n > 0 && ok {
 			maxInflight = n
 		}
 	}
 
-	go func() {
-		ac := kadm.NewClient(s.c)
-		ticker := time.NewTicker(DefaultStatsInterval)
-
-		for {
-			select {
-			case <-ctx.Done():
-				ticker.Stop()
-				return
-			case <-ticker.C:
-				dgls, err := ac.Lag(ctx, s.opts.Group)
-				if err != nil || !dgls.Ok() {
-					continue
-				}
-
-				dgl, ok := dgls[s.opts.Group]
-				if !ok {
-					continue
-				}
-				lmap, ok := dgl.Lag[s.topic]
-				if !ok {
-					continue
-				}
-
-				s.mu.Lock()
-				for p, l := range lmap {
-					s.kopts.Meter.Counter(semconv.BrokerGroupLag, "topic", s.topic, "group", s.opts.Group, "partition", strconv.Itoa(int(p))).Set(uint64(l.Lag))
-				}
-				s.mu.Unlock()
-
-			}
-		}
-	}()
-
 	for {
 		select {
 		case <-ctx.Done():
@@ -141,7 +107,11 @@ func (s *Subscriber) poll(ctx context.Context) {
 				return
 			}
 			fetches.EachError(func(t string, p int32, err error) {
-				s.kopts.Logger.Fatal(ctx, fmt.Sprintf("[kgo] fetch topic %s partition %d error", t, p), err)
+				if kgo.IsRetryableBrokerErr(err) {
+					s.kopts.Logger.Error(ctx, fmt.Sprintf("[kgo] fetch topic %s partition %d error", t, p), err)
+				} else {
+					s.kopts.Logger.Fatal(ctx, fmt.Sprintf("[kgo] fetch topic %s partition %d error", t, p), err)
+				}
 			})
 
 			fetches.EachPartition(func(p kgo.FetchTopicPartition) {