Add docs and completion for docker node ls --filter node.label

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

contrib/completion/bash/docker

@@ -4355,6 +4355,9 @@ _docker_node_ls() {
 			__docker_complete_nodes --cur "${cur##*=}" --id
 			return
 			;;
+		label|node.label)
+			return
+			;;
 		membership)
 			COMPREPLY=( $( compgen -W "accepted pending" -- "${cur##*=}" ) )
 			return
@@ -4371,7 +4374,7 @@ _docker_node_ls() {
 
 	case "$prev" in
 		--filter|-f)
-			COMPREPLY=( $( compgen -W "id label membership name role" -S = -- "$cur" ) )
+			COMPREPLY=( $( compgen -W "id label membership name node.label role" -S = -- "$cur" ) )
 			__docker_nospace
 			return
 			;;

contrib/completion/zsh/_docker

@@ -1343,7 +1343,7 @@ __docker_node_complete_ls_filters() {
                 ;;
         esac
     else
-        opts=('id' 'label' 'membership' 'name' 'role')
+        opts=('id' 'label' 'membership' 'name' 'node.label' 'role')
         _describe -t filter-opts "filter options" opts -qS "=" && ret=0
     fi
 

docs/reference/commandline/node_ls.md

@@ -60,6 +60,7 @@ The currently supported filters are:
 
 * [id](#id)
 * [label](#label)
+* [node.label](#nodelabel)
 * [membership](#membership)
 * [name](#name)
 * [role](#role)
@@ -77,7 +78,10 @@ ID                         HOSTNAME       STATUS  AVAILABILITY  MANAGER STATUS
 
 #### label
 
-The `label` filter matches nodes based on engine labels and on the presence of a `label` alone or a `label` and a value. Node labels are currently not used for filtering.
+The `label` filter matches nodes based on engine labels and on the presence of a
+`label` alone or a `label` and a value. Engine labels are configured in
+the [daemon configuration](dockerd.md#daemon-configuration-file). To filter on
+Swarm `node` labels, use [`node.label` instead](#nodelabel).
 
 The following filter matches nodes with the `foo` label regardless of its value.
 
@@ -88,6 +92,42 @@ ID                         HOSTNAME       STATUS  AVAILABILITY  MANAGER STATUS
 1bcef6utixb0l0ca7gxuivsj0  swarm-worker2  Ready   Active
 ```
 
+#### node.label
+
+The `node.label` filter matches nodes based on node labels and on the presence
+of a `node.label` alone or a `node.label` and a value.
+
+The following filter updates nodes to have a `region` node label:
+
+```console
+$ docker node update --label-add region=region-a swarm-test-01
+$ docker node update --label-add region=region-a swarm-test-02
+$ docker node update --label-add region=region-b swarm-test-03
+$ docker node update --label-add region=region-b swarm-test-04
+```
+
+Show all nodes that have a `region` node label set:
+
+```console
+$ docker node ls --filter node.label=region
+
+ID                            HOSTNAME        STATUS    AVAILABILITY   MANAGER STATUS   ENGINE VERSION
+yg550ettvsjn6g6t840iaiwgb *   swarm-test-01   Ready     Active         Leader           20.10.2
+2lm9w9kbepgvkzkkeyku40e65     swarm-test-02   Ready     Active         Reachable        20.10.2
+hc0pu7ntc7s4uvj4pv7z7pz15     swarm-test-03   Ready     Active         Reachable        20.10.2
+n41b2cijmhifxxvz56vwrs12q     swarm-test-04   Ready     Active                          20.10.2
+```
+
+Show all nodes that have a `region` node label, with value `region-a`:
+
+```console
+$ docker node ls --filter node.label=region=region-a
+
+ID                            HOSTNAME        STATUS    AVAILABILITY   MANAGER STATUS   ENGINE VERSION
+yg550ettvsjn6g6t840iaiwgb *   swarm-test-01   Ready     Active         Leader           20.10.2
+2lm9w9kbepgvkzkkeyku40e65     swarm-test-02   Ready     Active         Reachable        20.10.2
+```
+
 #### membership
 
 The `membership` filter matches nodes based on the presence of a `membership` and a value