Add DeployIdentifier to Swift set_swift_secret container

Resolves an issue during scale out where the Swift set_swift_secret
container that sets the required Barbican key ID wasn't executing on a
Heat stack update if the container name and configs all stayed the same.

Closes-bug: 1767395
Change-Id: I683bb9e96eef73a014d5967a5930ef519ac34430

docker/services/swift-proxy.yaml

@@ -51,6 +51,12 @@ parameters:
     type: boolean
     description: Flag to indicate undercloud upgrade process is being run.
     default: false
+  DeployIdentifier:
+    default: ''
+    type: string
+    description: >
+      Setting this to a unique value will re-run any deployment tasks which
+      perform configuration on a Heat stack-update.
 
 conditions:
 
@@ -193,6 +199,13 @@ outputs:
                             - /var/lib/docker-config-scripts/set_swift_keymaster_key_id.sh:/set_swift_keymaster_key_id.sh:ro
                     user: root
                     command: "/set_swift_keymaster_key_id.sh"
+                    environment:
+                      # NOTE: this should force this container to re-run on each
+                      # update (scale-out, etc.)
+                      - list_join:
+                          - ''
+                          - - 'TRIPLEO_DEPLOY_IDENTIFIER='
+                            - {get_param: DeployIdentifier}
                 - {}
             - swift_proxy:
                 image: *swift_proxy_image