@@ -60,7 +60,7 @@ type RaftConfig struct {

 	// KeepOldSnapshots is the number of snapshots to keep beyond the

 	// current snapshot.

-	KeepOldSnapshots uint64 `json:",omitempty"`

+	KeepOldSnapshots *uint64 `json:",omitempty"`

 	// LogEntriesForSlowFollowers is the number of log entries to keep

 	// around to sync up slow followers after a snapshot is created.

@@ -24,6 +24,8 @@ const (

 	flagToken               = "token"

 	flagTaskHistoryLimit    = "task-history-limit"

 	flagExternalCA          = "external-ca"

+	flagMaxSnapshots        = "max-snapshots"

+	flagSnapshotInterval    = "snapshot-interval"

 )

 type swarmOptions struct {

@@ -31,6 +33,8 @@ type swarmOptions struct {

 	dispatcherHeartbeat time.Duration

 	nodeCertExpiry      time.Duration

 	externalCA          ExternalCAOption

+	maxSnapshots        uint64

+	snapshotInterval    uint64

 }

 // NodeAddrOption is a pflag.Value for listening addresses

@@ -167,11 +171,11 @@ func addSwarmFlags(flags *pflag.FlagSet, opts *swarmOptions) {

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

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

 	flags.Var(&opts.externalCA, flagExternalCA, "Specifications of one or more certificate signing endpoints")

+	flags.Uint64Var(&opts.maxSnapshots, flagMaxSnapshots, 0, "Number of additional Raft snapshots to retain")

+	flags.Uint64Var(&opts.snapshotInterval, flagSnapshotInterval, 10000, "Number of log entries between Raft snapshots")

 }

-func (opts *swarmOptions) ToSpec(flags *pflag.FlagSet) swarm.Spec {

-	spec := swarm.Spec{}

-

+func (opts *swarmOptions) mergeSwarmSpec(spec *swarm.Spec, flags *pflag.FlagSet) {

 	if flags.Changed(flagTaskHistoryLimit) {

 		spec.Orchestration.TaskHistoryRetentionLimit = &opts.taskHistoryLimit

 	}

@@ -184,5 +188,16 @@ func (opts *swarmOptions) ToSpec(flags *pflag.FlagSet) swarm.Spec {

 	if flags.Changed(flagExternalCA) {

 		spec.CAConfig.ExternalCAs = opts.externalCA.Value()

 	}

+	if flags.Changed(flagMaxSnapshots) {

+		spec.Raft.KeepOldSnapshots = &opts.maxSnapshots

+	}

+	if flags.Changed(flagSnapshotInterval) {

+		spec.Raft.SnapshotInterval = opts.snapshotInterval

+	}

+}

+

+func (opts *swarmOptions) ToSpec(flags *pflag.FlagSet) swarm.Spec {

+	var spec swarm.Spec

+	opts.mergeSwarmSpec(&spec, flags)

 	return spec

 }

@@ -39,10 +39,7 @@ func runUpdate(dockerCli *command.DockerCli, flags *pflag.FlagSet, opts swarmOpt

 		return err

 	}

-	err = mergeSwarm(&swarm, flags)

-	if err != nil {

-		return err

-	}

+	opts.mergeSwarmSpec(&swarm.Spec, flags)

 	err = client.SwarmUpdate(ctx, swarm.Version, swarm.Spec, updateFlags)

 	if err != nil {

@@ -53,31 +50,3 @@ func runUpdate(dockerCli *command.DockerCli, flags *pflag.FlagSet, opts swarmOpt

 	return nil

 }

-

-func mergeSwarm(swarm *swarm.Swarm, flags *pflag.FlagSet) error {

-	spec := &swarm.Spec

-

-	if flags.Changed(flagTaskHistoryLimit) {

-		taskHistoryRetentionLimit, _ := flags.GetInt64(flagTaskHistoryLimit)

-		spec.Orchestration.TaskHistoryRetentionLimit = &taskHistoryRetentionLimit

-	}

-

-	if flags.Changed(flagDispatcherHeartbeat) {

-		if v, err := flags.GetDuration(flagDispatcherHeartbeat); err == nil {

-			spec.Dispatcher.HeartbeatPeriod = v

-		}

-	}

-

-	if flags.Changed(flagCertExpiry) {

-		if v, err := flags.GetDuration(flagCertExpiry); err == nil {

-			spec.CAConfig.NodeCertExpiry = v

-		}

-	}

-

-	if flags.Changed(flagExternalCA) {

-		value := flags.Lookup(flagExternalCA).Value.(*ExternalCAOption)

-		spec.CAConfig.ExternalCAs = value.Value()

-	}

-

-	return nil

-}

@@ -114,6 +114,9 @@ func prettyPrintInfo(dockerCli *command.DockerCli, info types.Info) error {

 			fmt.Fprintf(dockerCli.Out(), "  Task History Retention Limit: %d\n", taskHistoryRetentionLimit)

 			fmt.Fprintf(dockerCli.Out(), " Raft:\n")

 			fmt.Fprintf(dockerCli.Out(), "  Snapshot Interval: %d\n", info.Swarm.Cluster.Spec.Raft.SnapshotInterval)

+			if info.Swarm.Cluster.Spec.Raft.KeepOldSnapshots != nil {

+				fmt.Fprintf(dockerCli.Out(), "  Number of Old Snapshots to Retain: %d\n", *info.Swarm.Cluster.Spec.Raft.KeepOldSnapshots)

+			}

 			fmt.Fprintf(dockerCli.Out(), "  Heartbeat Tick: %d\n", info.Swarm.Cluster.Spec.Raft.HeartbeatTick)

 			fmt.Fprintf(dockerCli.Out(), "  Election Tick: %d\n", info.Swarm.Cluster.Spec.Raft.ElectionTick)

 			fmt.Fprintf(dockerCli.Out(), " Dispatcher:\n")

@@ -2841,14 +2841,14 @@ _docker_swarm_leave() {

 _docker_swarm_update() {

 	case "$prev" in

-		--cert-expiry|--dispatcher-heartbeat|--task-history-limit)

+		--cert-expiry|--dispatcher-heartbeat|--max-snapshots|--snapshot-interval|--task-history-limit)

 			return

 			;;

 	esac

 	case "$cur" in

 		-*)

-			COMPREPLY=( $( compgen -W "--cert-expiry --dispatcher-heartbeat --help --task-history-limit" -- "$cur" ) )

+			COMPREPLY=( $( compgen -W "--cert-expiry --dispatcher-heartbeat --help --max-snapshots --snapshot-interval --task-history-limit" -- "$cur" ) )

 			;;

 	esac

 }

@@ -1630,7 +1630,10 @@ __docker_swarm_subcommand() {

                 "($help)--advertise-addr[Advertised address]:ip\:port: " \

                 "($help)*--external-ca=[Specifications of one or more certificate signing endpoints]:endpoint: " \

                 "($help)--force-new-cluster[Force create a new cluster from current state]" \

-                "($help)--listen-addr=[Listen address]:ip\:port: " && ret=0

+                "($help)--listen-addr=[Listen address]:ip\:port: " \

+                "($help)--max-snapshots[Number of additional Raft snapshots to retain]" \

+                "($help)--snapshot-interval[Number of log entries between Raft snapshots]" \

+                "($help)--task-history-limit=[Task history retention limit]:limit: " && ret=0

             ;;

         (join)

             _arguments $(__docker_arguments) \

@@ -1655,7 +1658,10 @@ __docker_swarm_subcommand() {

             _arguments $(__docker_arguments) \

                 $opts_help \

                 "($help)--cert-expiry=[Validity period for node certificates]:duration: " \

+                "($help)*--external-ca=[Specifications of one or more certificate signing endpoints]:endpoint: " \

                 "($help)--dispatcher-heartbeat=[Dispatcher heartbeat period]:duration: " \

+                "($help)--max-snapshots[Number of additional Raft snapshots to retain]" \

+                "($help)--snapshot-interval[Number of log entries between Raft snapshots]" \

                 "($help)--task-history-limit=[Task history retention limit]:limit: " && ret=0

             ;;

         (help)

@@ -21,7 +21,7 @@ func SwarmFromGRPC(c swarmapi.Cluster) types.Swarm {

 				},

 				Raft: types.RaftConfig{

 					SnapshotInterval:           c.Spec.Raft.SnapshotInterval,

-					KeepOldSnapshots:           c.Spec.Raft.KeepOldSnapshots,

+					KeepOldSnapshots:           &c.Spec.Raft.KeepOldSnapshots,

 					LogEntriesForSlowFollowers: c.Spec.Raft.LogEntriesForSlowFollowers,

 					HeartbeatTick:              int(c.Spec.Raft.HeartbeatTick),

 					ElectionTick:               int(c.Spec.Raft.ElectionTick),

@@ -82,8 +82,8 @@ func MergeSwarmSpecToGRPC(s types.Spec, spec swarmapi.ClusterSpec) (swarmapi.Clu

 	if s.Raft.SnapshotInterval != 0 {

 		spec.Raft.SnapshotInterval = s.Raft.SnapshotInterval

 	}

-	if s.Raft.KeepOldSnapshots != 0 {

-		spec.Raft.KeepOldSnapshots = s.Raft.KeepOldSnapshots

+	if s.Raft.KeepOldSnapshots != nil {

+		spec.Raft.KeepOldSnapshots = *s.Raft.KeepOldSnapshots

 	}

 	if s.Raft.LogEntriesForSlowFollowers != 0 {

 		spec.Raft.LogEntriesForSlowFollowers = s.Raft.LogEntriesForSlowFollowers

@@ -28,6 +28,8 @@ Options:

       --force-new-cluster               Force create a new cluster from current state

       --help                            Print usage

       --listen-addr value               Listen address (format: <ip|interface>[:port])

+      --max-snapshots int               Number of additional Raft snapshots to retain

+      --snapshot-interval int           Number of log entries between Raft snapshots

       --task-history-limit int          Task history retention limit (default 5)

 ```

@@ -64,7 +66,7 @@ This flag sets the validity period for node certificates.

 This flags sets the frequency with which nodes are told to use as a

 period to report their health.

-### `--external-ca value`

+### `--external-ca`

 This flag sets up the swarm to use an external CA to issue node certificates. The value takes

 the form `protocol=X,url=Y`. The value for `protocol` specifies what protocol should be used

@@ -75,7 +77,7 @@ The URL specifies the endpoint where signing requests should be submitted.

 This flag forces an existing node that was part of a quorum that was lost to restart as a single node Manager without losing its data.

-### `--listen-addr value`

+### `--listen-addr`

 The node listens for inbound swarm manager traffic on this address. The default is to listen on

 0.0.0.0:2377. It is also possible to specify a network interface to listen on that interface's

@@ -84,7 +86,7 @@ address; for example `--listen-addr eth0:2377`.

 Specifying a port is optional. If the value is a bare IP address or interface

 name, the default port 2377 will be used.

-### `--advertise-addr value`

+### `--advertise-addr`

 This flag specifies the address that will be advertised to other members of the

 swarm for API access and overlay networking. If unspecified, Docker will check

@@ -103,6 +105,21 @@ name, the default port 2377 will be used.

 This flag sets up task history retention limit.

+### `--max-snapshots`

+

+This flag sets the number of old Raft snapshots to retain in addition to the

+current Raft snapshots. By default, no old snapshots are retained. This option

+may be used for debugging, or to store old snapshots of the swarm state for

+disaster recovery purposes.

+

+### `--snapshot-interval`

+

+This flag specifies how many log entries to allow in between Raft snapshots.

+Setting this to a higher number will trigger snapshots less frequently.

+Snapshots compact the Raft log and allow for more efficient transfer of the

+state to new managers. However, there is a performance cost to taking snapshots

+frequently.

+

 ## Related information

 * [swarm join](swarm_join.md)

@@ -25,6 +25,8 @@ Options:

       --dispatcher-heartbeat duration   Dispatcher heartbeat period (default 5s)

       --external-ca value               Specifications of one or more certificate signing endpoints

       --help                            Print usage

+      --max-snapshots int               Number of additional Raft snapshots to retain

+      --snapshot-interval int           Number of log entries between Raft snapshots

       --task-history-limit int          Task history retention limit (default 5)

 ```