@@ -18,6 +18,7 @@ type updateOptions struct {

 	secret              string

 	taskHistoryLimit    int64

 	dispatcherHeartbeat time.Duration

+	nodeCertExpiry      time.Duration

 }

 func newUpdateCommand(dockerCli *client.DockerCli) *cobra.Command {

@@ -38,6 +39,7 @@ func newUpdateCommand(dockerCli *client.DockerCli) *cobra.Command {

 	flags.StringVar(&opts.secret, "secret", "", "Set secret value needed to accept nodes into cluster")

 	flags.Int64Var(&opts.taskHistoryLimit, "task-history-limit", 10, "Task history retention limit")

 	flags.DurationVar(&opts.dispatcherHeartbeat, "dispatcher-heartbeat", time.Duration(5*time.Second), "Dispatcher heartbeat period")

+	flags.DurationVar(&opts.nodeCertExpiry, "cert-expiry", time.Duration(90*24*time.Hour), "Validity period for node certificates")

 	return cmd

 }

@@ -92,5 +94,11 @@ func mergeSwarm(swarm *swarm.Swarm, flags *pflag.FlagSet) error {

 		}

 	}

+	if flags.Changed("cert-expiry") {

+		if v, err := flags.GetDuration("cert-expiry"); err == nil {

+			spec.CAConfig.NodeCertExpiry = v

+		}

+	}

+

 	return nil

 }

@@ -22,6 +22,7 @@ parent = "smn_cli"

           --help                            Print usage

           --secret string                   Set secret value needed to accept nodes into cluster

           --task-history-limit int          Task history retention limit (default 10)

+          --cert-expiry duration            Validity period for node certificates (default 2160h0m0s)

 Updates a Swarm cluster with new parameter values. This command must target a manager node.