Improve bash completion for `docker swarm {init,join} --{advertise,listen}-addr}`

Signed-off-by: Harald Albers <github@albersweb.de>

contrib/completion/bash/docker

@@ -414,6 +414,20 @@ __docker_complete_resolved_hostname() {
 	COMPREPLY=( $(host 2>/dev/null "${cur%:}" | awk '/has address/ {print $4}') )
 }
 
+__docker_local_interfaces() {
+	command -v ip >/dev/null 2>&1 || return
+	ip addr show scope global 2>/dev/null | sed -n 's| \+inet \([0-9.]\+\).* \([^ ]\+\)|\1 \2|p'
+}
+
+__docker_complete_local_interfaces() {
+	local additional_interface
+	if [ "$1" = "--add" ] ; then
+		additional_interface="$2"
+	fi
+
+	COMPREPLY=( $( compgen -W "$(__docker_local_interfaces) $additional_interface" -- "$cur" ) )
+}
+
 __docker_complete_capabilities() {
 	# The list of capabilities is defined in types.go, ALL was added manually.
 	COMPREPLY=( $( compgen -W "
@@ -1836,15 +1850,21 @@ _docker_swarm() {
 
 _docker_swarm_init() {
 	case "$prev" in
-		--listen-addr)
+		--advertise-addr)
 			if [[ $cur == *: ]] ; then
 				COMPREPLY=( $( compgen -W "2377" -- "${cur##*:}" ) )
+			else
+				__docker_complete_local_interfaces
+				__docker_nospace
 			fi
 			return
 			;;
-		--advertise-addr)
+		--listen-addr)
 			if [[ $cur == *: ]] ; then
 				COMPREPLY=( $( compgen -W "2377" -- "${cur##*:}" ) )
+			else
+				__docker_complete_local_interfaces --add 0.0.0.0
+				__docker_nospace
 			fi
 			return
 			;;
@@ -1859,21 +1879,27 @@ _docker_swarm_init() {
 
 _docker_swarm_join() {
 	case "$prev" in
-		--token)
-			return
-			;;
-		--listen-addr)
+		--advertise-addr)
 			if [[ $cur == *: ]] ; then
 				COMPREPLY=( $( compgen -W "2377" -- "${cur##*:}" ) )
+			else
+				__docker_complete_local_interfaces
+				__docker_nospace
 			fi
 			return
 			;;
-		--advertise-addr)
+		--listen-addr)
 			if [[ $cur == *: ]] ; then
 				COMPREPLY=( $( compgen -W "2377" -- "${cur##*:}" ) )
+			else
+				__docker_complete_local_interfaces --add 0.0.0.0
+				__docker_nospace
 			fi
 			return
 			;;
+		--token)
+			return
+			;;
 	esac
 
 	case "$cur" in