Allow to pass docker UCP image via env file

Related-Prod: PRODX-3456
Change-Id: I2f34e6912b108df68092ab29d8baed87e56ce861
diff --git a/de/heat-templates/top.yaml b/de/heat-templates/top.yaml
index 8f40a87..6ec1e76 100644
--- a/de/heat-templates/top.yaml
+++ b/de/heat-templates/top.yaml
@@ -199,6 +199,9 @@
   docker_ee_release:
     type: string
     default: 'stable-19.03'
+  docker_ucp_image:
+    type: string
+    default: 'docker/ucp:3.2.4'
   tunnel_interface:
     type: string
     default: ''
@@ -259,6 +262,7 @@
       metadata: { get_param: ucp_metadata}
       docker_ee_url: { get_param: docker_ee_url }
       docker_ee_release: { get_param: docker_ee_release }
+      docker_ucp_image: { get_param: docker_ucp_image}
       node_type: "ucp"
       key_name: { get_param: "OS::stack_name" }
       image: { get_param: image }