docker: configure group/user for deployment_user

See context here: Ia5cc7b34ebee8cf2f49300ce23050370d5f1038a

This user will be useful for containerized undercloud, to maintain
parity with what was done in instack-undercloud.

Depends-On: Ia5cc7b34ebee8cf2f49300ce23050370d5f1038a
Depends-On: Ifd1bec1262dfbd213810bb2b4d561f47bf010e69
Change-Id: I48ab4a0ba0240e931391602943b471b5b6ec8e80

puppet/services/docker.yaml

@@ -54,11 +54,16 @@ parameters:
     default: '--log-driver=journald --signature-verification=false --iptables=false --live-restore'
     description: Options that are used to startup the docker service.
     type: string
+  DeploymentUser:
+    default: ''
+    description: User added to the docker group in order to use container commands.
+    type: string
 
 conditions:
   insecure_registry_is_empty: {equals : [{get_param: DockerInsecureRegistryAddress}, []]}
   insecure_registry_mirror_is_empty: {equals : [{get_param: DockerRegistryMirror}, '']}
   service_debug_unset: {equals : [{get_param: DockerDebug}, '']}
+  deployment_user_is_empty: {equals : [{get_param: DeploymentUser}, '']}
 
 outputs:
   role_data:
@@ -85,6 +90,11 @@ outputs:
             - insecure_registry_mirror_is_empty
             - {}
             - tripleo::profile::base::docker::registry_mirror: {get_param: DockerRegistryMirror}
+          -
+            if:
+            - deployment_user_is_empty
+            - {}
+            - tripleo::profile::base::docker::deployment_user: {get_param: DeploymentUser}
       step_config: |
         include ::tripleo::profile::base::docker
       upgrade_tasks: