Global Default Address Pool feature support

This feature brings new attribute/option for swarm init command.
default-addr-pool will take string input which can be in below format.
"CIDR,CIDR,CIDR...:SUBNET-SIZE".

Signed-off-by: selansen <elango.siva@docker.com>

cli/command/swarm/init.go

@@ -21,6 +21,7 @@ type initOptions struct {
 	dataPathAddr    string
 	forceNewCluster bool
 	availability    string
+	defaultAddrPool string
 }
 
 func newInitCommand(dockerCli command.Cli) *cobra.Command {
@@ -44,6 +45,7 @@ func newInitCommand(dockerCli command.Cli) *cobra.Command {
 	flags.BoolVar(&opts.forceNewCluster, "force-new-cluster", false, "Force create a new cluster from current state")
 	flags.BoolVar(&opts.autolock, flagAutolock, false, "Enable manager autolocking (requiring an unlock key to start a stopped manager)")
 	flags.StringVar(&opts.availability, flagAvailability, "active", `Availability of the node ("active"|"pause"|"drain")`)
+	flags.StringVar(&opts.defaultAddrPool, flagDefaultAddrPool, "", "List of default subnet addresses followed by subnet size (format: <subnet,subnet,..:subnet-size)")
 	addSwarmFlags(flags, &opts.swarmOptions)
 	return cmd
 }
@@ -56,6 +58,7 @@ func runInit(dockerCli command.Cli, flags *pflag.FlagSet, opts initOptions) erro
 		ListenAddr:       opts.listenAddr.String(),
 		AdvertiseAddr:    opts.advertiseAddr,
 		DataPathAddr:     opts.dataPathAddr,
+		DefaultAddrPool:  opts.defaultAddrPool,
 		ForceNewCluster:  opts.forceNewCluster,
 		Spec:             opts.swarmOptions.ToSpec(flags),
 		AutoLockManagers: opts.swarmOptions.autolock,

cli/command/swarm/opts.go

@@ -22,6 +22,7 @@ const (
 	flagListenAddr          = "listen-addr"
 	flagAdvertiseAddr       = "advertise-addr"
 	flagDataPathAddr        = "data-path-addr"
+	flagDefaultAddrPool     = "default-addr-pool"
 	flagQuiet               = "quiet"
 	flagRotate              = "rotate"
 	flagToken               = "token"

contrib/completion/bash/docker

@@ -3667,6 +3667,10 @@ _docker_swarm_init() {
 			__docker_complete_local_interfaces
 			return
 			;;
+		--default-addr-pool)
+			COMPREPLY=( $( compgen -W "list of subnet addresses followed by subnet size" -- "$cur" ) )
+			return
+			;;
 		--listen-addr)
 			if [[ $cur == *: ]] ; then
 				COMPREPLY=( $( compgen -W "2377" -- "${cur##*:}" ) )
@@ -3680,7 +3684,7 @@ _docker_swarm_init() {
 
 	case "$cur" in
 		-*)
-			COMPREPLY=( $( compgen -W "--advertise-addr --autolock --availability --cert-expiry --data-path-addr --dispatcher-heartbeat --external-ca --force-new-cluster --help --listen-addr --max-snapshots --snapshot-interval --task-history-limit" -- "$cur" ) )
+			COMPREPLY=( $( compgen -W "--advertise-addr --autolock --availability --cert-expiry --data-path-addr --default-addr-pool --dispatcher-heartbeat --external-ca --force-new-cluster --help --listen-addr --max-snapshots --snapshot-interval --task-history-limit" -- "$cur" ) )
 			;;
 	esac
 }

contrib/completion/zsh/_docker

@@ -2280,6 +2280,7 @@ __docker_swarm_subcommand() {
                 $opts_help \
                 "($help)--advertise-addr=[Advertised address]:ip\:port: " \
                 "($help)--data-path-addr=[Data path IP or interface]:ip " \
+                "($help)--default-addr-pool=[default subnet addresses]:subnet-size " \
                 "($help)--autolock[Enable manager autolocking]" \
                 "($help)--availability=[Availability of the node]:availability:(active drain pause)" \
                 "($help)--cert-expiry=[Validity period for node certificates]:duration: " \

docs/reference/commandline/swarm_init.md

@@ -26,6 +26,7 @@ Options:
       --availability string             Availability of the node ("active"|"pause"|"drain") (default "active")
       --cert-expiry duration            Validity period for node certificates (ns|us|ms|s|m|h) (default 2160h0m0s)
       --data-path-addr string           Address or interface to use for data path traffic (format: <ip|interface>)
+      --default-addr-pool string	List of default subnet addresses followed by subnet size (format: <subnet,subnet,..:subnet-size)
       --dispatcher-heartbeat duration   Dispatcher heartbeat period (ns|us|ms|s|m|h) (default 5s)
       --external-ca external-ca         Specifications of one or more certificate signing endpoints
       --force-new-cluster               Force create a new cluster from current state
@@ -128,6 +129,11 @@ management traffic of the cluster.
 If unspecified, Docker will use the same IP address or interface that is used for the
 advertise address.
 
+### `--default-addr-pool`
+This flag specifies default subnet pools for global scope networks. If subnet size is not
+specified then default value 24 will be used.
+If unspecified, Docker will use the predefined subnets as it works on older releases.
+
 ### `--task-history-limit`
 
 This flag sets up task history retention limit.