cluster: configurable session TTL for the leader elector

cluster/etcd_elector.go

@@ -35,7 +35,7 @@ type etcdLeaderElector struct {
 
 // newEtcdLeaderElector constructs a new etcdLeaderElector.
 func newEtcdLeaderElector(ctx context.Context, id, electionPrefix string,
-	cfg *etcd.Config) (*etcdLeaderElector, error) {
+	leaderSessionTTL int, cfg *etcd.Config) (*etcdLeaderElector, error) {
 
 	clientCfg := clientv3.Config{
 		Context:     ctx,
@@ -72,7 +72,9 @@ func newEtcdLeaderElector(ctx context.Context, id, electionPrefix string,
 	cli.Lease = namespace.NewLease(cli.Lease, cfg.Namespace)
 	log.Infof("Applied namespace to leader elector: %v", cfg.Namespace)
 
-	session, err := concurrency.NewSession(cli)
+	session, err := concurrency.NewSession(
+		cli, concurrency.WithTTL(leaderSessionTTL),
+	)
 	if err != nil {
 		log.Errorf("Unable to start new leader election session: %v",
 			err)

cluster/etcd_elector_factory.go

@@ -15,9 +15,9 @@ import (
 func makeEtcdElector(ctx context.Context, args ...interface{}) (LeaderElector,
 	error) {
 
-	if len(args) != 3 {
+	if len(args) != 4 {
 		return nil, fmt.Errorf("invalid number of arguments to "+
-			"cluster.makeEtcdElector(): expected 3, got %v",
+			"cluster.makeEtcdElector(): expected 4, got %v",
 			len(args))
 	}
 
@@ -33,13 +33,21 @@ func makeEtcdElector(ctx context.Context, args ...interface{}) (LeaderElector,
 			"cluster.makeEtcdElector(), expected: string")
 	}
 
-	etcdCfg, ok := args[2].(*etcd.Config)
+	leaderSessionTTL, ok := args[2].(int)
 	if !ok {
 		return nil, fmt.Errorf("invalid argument (2) to " +
+			"cluster.makeEtcdElector(), expected: int")
+	}
+
+	etcdCfg, ok := args[3].(*etcd.Config)
+	if !ok {
+		return nil, fmt.Errorf("invalid argument (3) to " +
 			"cluster.makeEtcdElector(), expected: *etcd.Config")
 	}
 
-	return newEtcdLeaderElector(ctx, id, electionPrefix, etcdCfg)
+	return newEtcdLeaderElector(
+		ctx, id, electionPrefix, leaderSessionTTL, etcdCfg,
+	)
 }
 
 func init() {

cluster/etcd_elector_test.go

@@ -57,15 +57,16 @@ func TestEtcdElector(t *testing.T) {
 		election = "/election/"
 		id1      = "e1"
 		id2      = "e2"
+		ttl      = 5
 	)
 
 	e1, err := newEtcdLeaderElector(
-		ctx, id1, election, etcdCfg,
+		ctx, id1, election, ttl, etcdCfg,
 	)
 	require.NoError(t, err)
 
 	e2, err := newEtcdLeaderElector(
-		ctx, id2, election, etcdCfg,
+		ctx, id2, election, ttl, etcdCfg,
 	)
 	require.NoError(t, err)