Make service completion faster

Signed-off-by: Morten Hekkvang <morten.hekkvang@sbab.se>

contrib/completion/bash/docker

@@ -550,17 +550,18 @@ __docker_complete_nodes() {
 # output to the IDs or names of matching items. This setting takes
 # precedence over the environment setting.
 __docker_services() {
-	local fields='$2'  # default: service name only
-	[ "${DOCKER_COMPLETION_SHOW_SERVICE_IDS}" = yes ] && fields='$1,$2' # ID & name
+	local format='{{.Name}}'  # default: service name only
+	[ "${DOCKER_COMPLETION_SHOW_SERVICE_IDS}" = yes ] && format='{{.ID}},{{.Name}}' # ID & name
 
 	if [ "$1" = "--id" ] ; then
-		fields='$1' # IDs only
+		format='{{.ID}}' # IDs only
 		shift
 	elif [ "$1" = "--name" ] ; then
-		fields='$2' # names only
+		format='{{.Name}}' # names only
 		shift
 	fi
-        __docker_q service ls "$@" | awk "NR>1 {print $fields}"
+
+  __docker_q service ls -q --format "$format" --filter "name=$1"
 }
 
 # __docker_complete_services applies completion of services based on the current
@@ -572,7 +573,7 @@ __docker_complete_services() {
 		current="$2"
 		shift 2
 	fi
-	COMPREPLY=( $(compgen -W "$(__docker_services "$@")" -- "$current") )
+	COMPREPLY=( $(__docker_services "$@" "$current") )
 }
 
 # __docker_tasks returns a list of all task IDs.