Save bootstrap trace events in a circular buffer (#16823)

cmd/admin-handlers.go

@@ -1526,6 +1526,11 @@ func (a adminAPIHandlers) TraceHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Publish bootstrap events that have already occurred before client could subscribe.
+	if traceOpts.TraceTypes().Contains(madmin.TraceBootstrap) {
+		go globalBootstrapTracer.Publish(ctx, globalTrace)
+	}
+
 	for _, peer := range peers {
 		if peer == nil {
 			continue

cmd/bootstrap-messages.go

@@ -0,0 +1,116 @@
+// Copyright (c) 2015-2023 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/minio/madmin-go/v2"
+	"github.com/minio/minio/internal/pubsub"
+)
+
+const bootstrapMsgsLimit = 4 << 10
+
+type bootstrapInfo struct {
+	msg    string
+	ts     time.Time
+	source string
+}
+type bootstrapTracer struct {
+	mu         sync.RWMutex
+	idx        int
+	info       [bootstrapMsgsLimit]bootstrapInfo
+	lastUpdate time.Time
+}
+
+var globalBootstrapTracer = &bootstrapTracer{}
+
+func (bs *bootstrapTracer) DropEvents() {
+	bs.mu.Lock()
+	defer bs.mu.Unlock()
+
+	if time.Now().UTC().Sub(bs.lastUpdate) > 24*time.Hour {
+		bs.info = [4096]bootstrapInfo{}
+		bs.idx = 0
+	}
+}
+
+func (bs *bootstrapTracer) Empty() bool {
+	var empty bool
+	bs.mu.RLock()
+	empty = bs.info[0].msg == ""
+	bs.mu.RUnlock()
+
+	return empty
+}
+
+func (bs *bootstrapTracer) Record(msg string) {
+	source := getSource(2)
+	bs.mu.Lock()
+	now := time.Now().UTC()
+	bs.info[bs.idx] = bootstrapInfo{
+		msg:    msg,
+		ts:     now,
+		source: source,
+	}
+	bs.lastUpdate = now
+	bs.idx = (bs.idx + 1) % bootstrapMsgsLimit
+	bs.mu.Unlock()
+}
+
+func (bs *bootstrapTracer) Events() []madmin.TraceInfo {
+	traceInfo := make([]madmin.TraceInfo, 0, bootstrapMsgsLimit)
+	
+	// Add all messages in order
+	addAll := func(info []bootstrapInfo) {
+		for _, msg := range info {
+			if msg.ts.IsZero() {
+				continue // skip empty events
+			}
+			traceInfo = append(traceInfo, madmin.TraceInfo{
+				TraceType: madmin.TraceBootstrap,
+				Time:      msg.ts,
+				NodeName:  globalLocalNodeName,
+				FuncName:  "BOOTSTRAP",
+				Message:   fmt.Sprintf("%s %s", msg.source, msg.msg),
+			})
+		}
+	}
+
+	bs.mu.RLock()
+	addAll(bs.info[bs.idx:])
+	addAll(bs.info[:bs.idx])
+	bs.mu.RUnlock()
+	return traceInfo
+}
+
+func (bs *bootstrapTracer) Publish(ctx context.Context, trace *pubsub.PubSub[madmin.TraceInfo, madmin.TraceType]) {
+	if bs.Empty() {
+		return
+	}
+	for _, bsEvent := range bs.Events() {
+		select {
+		case <-ctx.Done():
+		default:
+			trace.Publish(bsEvent)
+		}
+	}
+}

cmd/bootstrap-messages_test.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2015-2023 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package cmd
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestBootstrap(t *testing.T) {
+	// Bootstrap events exceed bootstrap messages limit
+	bsTracer := &bootstrapTracer{}
+	for i := 0; i < bootstrapMsgsLimit+10; i++ {
+		bsTracer.Record(fmt.Sprintf("msg-%d", i))
+	}
+
+	traceInfos := bsTracer.Events()
+	if len(traceInfos) != bootstrapMsgsLimit {
+		t.Fatalf("Expected length of events %d but got %d", bootstrapMsgsLimit, len(traceInfos))
+	}
+
+	// Simulate the case where bootstrap events were updated a day ago
+	bsTracer.lastUpdate = time.Now().UTC().Add(-25 * time.Hour)
+	bsTracer.DropEvents()
+	if !bsTracer.Empty() {
+		t.Fatalf("Expected all bootstrap events to have been dropped, but found %d events", len(bsTracer.Events()))
+	}
+
+	// Fewer than 4K bootstrap events
+	for i := 0; i < 10; i++ {
+		bsTracer.Record(fmt.Sprintf("msg-%d", i))
+	}
+	events := bsTracer.Events()
+	if len(events) != 10 {
+		t.Fatalf("Expected length of events %d but got %d", 10, len(events))
+	}
+	for i, traceInfo := range bsTracer.Events() {
+		msg := fmt.Sprintf("msg-%d", i)
+		if !strings.HasSuffix(traceInfo.Message, msg) {
+			t.Fatalf("Expected %s but got %s", msg, traceInfo.Message)
+		}
+	}
+}

cmd/peer-rest-server.go

@@ -977,6 +977,12 @@ func (s *peerRESTServer) TraceHandler(w http.ResponseWriter, r *http.Request) {
 		s.writeErrorResponse(w, err)
 		return
 	}
+
+	// Publish bootstrap events that have already occurred before client could subscribe.
+	if traceOpts.TraceTypes().Contains(madmin.TraceBootstrap) {
+		go globalBootstrapTracer.Publish(r.Context(), globalTrace)
+	}
+
 	keepAliveTicker := time.NewTicker(500 * time.Millisecond)
 	defer keepAliveTicker.Stop()
 

cmd/server-main.go

@@ -352,6 +352,8 @@ func configRetriableErrors(err error) bool {
 }
 
 func bootstrapTrace(msg string) {
+	globalBootstrapTracer.Record(msg)
+
 	if globalTrace.NumSubscribers(madmin.TraceBootstrap) == 0 {
 		return
 	}