tool: dump tool supports index

tools/etcd-dump-logs/main.go

@@ -32,17 +32,28 @@ import (
 
 func main() {
 	from := flag.String("data-dir", "", "")
-	snapfile := flag.String("snap-file", "", "The base name of snapshot file to read")
+	snapfile := flag.String("start-snap", "", "The base name of snapshot file to start dumping")
+	index := flag.Uint64("start-index", 0, "The index to start dumping")
 	flag.Parse()
 	if *from == "" {
-		log.Fatal("Must provide -data-dir flag")
+		log.Fatal("Must provide -data-dir flag.")
+	}
+	if *snapfile != "" && *index != 0 {
+		log.Fatal("start-snap and start-index flags cannot be used together.")
 	}
 
 	var (
+		walsnap  walpb.Snapshot
 		snapshot *raftpb.Snapshot
 		err      error
 	)
 
+	isIndex := *index != 0
+
+	if isIndex {
+		fmt.Printf("Start dumping log entries from index %d.\n", *index)
+		walsnap.Index = *index
+	} else {
 		if *snapfile == "" {
 			ss := snap.New(snapDir(*from))
 			snapshot, err = ss.Load()
@@ -50,7 +61,6 @@ func main() {
 			snapshot, err = snap.Read(path.Join(snapDir(*from), *snapfile))
 		}
 
-	var walsnap walpb.Snapshot
 		switch err {
 		case nil:
 			walsnap.Index, walsnap.Term = snapshot.Metadata.Index, snapshot.Metadata.Term
@@ -62,6 +72,8 @@ func main() {
 		default:
 			log.Fatalf("Failed loading snapshot: %v", err)
 		}
+		fmt.Println("Start dupmping log entries from snapshot.")
+	}
 
 	w, err := wal.Open(walDir(*from), walsnap)
 	if err != nil {
@@ -69,7 +81,7 @@ func main() {
 	}
 	wmetadata, state, ents, err := w.ReadAll()
 	w.Close()
-	if err != nil {
+	if err != nil && (!isIndex || err != wal.ErrSnapshotNotFound) {
 		log.Fatalf("Failed reading WAL: %v", err)
 	}
 	id, cid := parseWALMetadata(wmetadata)