Support stepping down before shutting down

cmd/rqlited/flags.go

@@ -163,6 +163,9 @@ type Config struct {
 	// RaftShutdownOnRemove sets whether Raft should be shutdown if the node is removed
 	RaftShutdownOnRemove bool
 
+	// RaftStepdownOnShutdown sets whether Leadership should be relinquished on shutdown
+	RaftStepdownOnShutdown bool
+
 	// RaftNoFreelistSync disables syncing Raft database freelist to disk. When true,
 	// it improves the database write performance under normal operation, but requires
 	// a full database re-sync during recovery.
@@ -393,6 +396,7 @@ func ParseFlags(name, desc string, build *BuildInfo) (*Config, error) {
 	flag.Uint64Var(&config.RaftSnapThreshold, "raft-snap", 8192, "Number of outstanding log entries that trigger snapshot")
 	flag.DurationVar(&config.RaftSnapInterval, "raft-snap-int", 30*time.Second, "Snapshot threshold check interval")
 	flag.DurationVar(&config.RaftLeaderLeaseTimeout, "raft-leader-lease-timeout", 0, "Raft leader lease timeout. Use 0s for Raft default")
+	flag.BoolVar(&config.RaftStepdownOnShutdown, "raft-shutdown-stepdown", false, "Stepdown as leader before shutting down")
 	flag.BoolVar(&config.RaftShutdownOnRemove, "raft-remove-shutdown", false, "Shutdown Raft if node removed")
 	flag.BoolVar(&config.RaftNoFreelistSync, "raft-no-freelist-sync", false, "Do not sync Raft log database freelist to disk")
 	flag.StringVar(&config.RaftLogLevel, "raft-log-level", "INFO", "Minimum log level for Raft module")

cmd/rqlited/main.go

@@ -14,6 +14,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
+	"syscall"
 	"time"
 
 	consul "github.com/rqlite/rqlite-disco-clients/consul"
@@ -158,8 +159,17 @@ func main() {
 
 	// Block until signalled.
 	terminate := make(chan os.Signal, 1)
-	signal.Notify(terminate, os.Interrupt)
+	signal.Notify(terminate, syscall.SIGINT, syscall.SIGTERM, os.Interrupt)
 	<-terminate
+
+	if (cfg.RaftStepdownOnShutdown) {
+		if str.IsLeader() {
+			// Don't log a confusing message if not (probably) Leader
+			log.Printf("explicitly stepping down before shutdown")
+		}
+		// Perform a stepdown, ignore any errors.
+		str.Stepdown(true)
+	}
 	if err := str.Close(true); err != nil {
 		log.Printf("failed to close store: %s", err.Error())
 	}

store/store.go

@@ -417,6 +417,16 @@ func (s *Store) Bootstrap(servers ...*Server) error {
 	return nil
 }
 
+// Stepdown forces this node to relinquish leadership to another node in
+// the cluster. If this node is not the leader an error will be returned.
+func (s *Store) Stepdown(wait bool) error {
+	f := s.raft.LeadershipTransfer()
+	if !wait {
+		return nil
+	}
+	return f.(raft.Future).Error()
+}
+
 // Close closes the store. If wait is true, waits for a graceful shutdown.
 func (s *Store) Close(wait bool) (retErr error) {
 	defer func() {