container: build docker image in separate directory

roles/container/tasks/image.yml

@@ -1,12 +1,21 @@
 ---
 
 - name: Image build
-  when: dockerfile is defined and dockerfile | length > 0
+  when: dockerfile_needed
   block:
+    - name: Set docker_build_directory variable
+      set_fact:
+        docker_build_directory: /opt/{{ docker_service }}/build
+
+    - name: Create container build directory
+      file:
+        path: "{{ docker_build_directory }}"
+        state: directory
+
     - name: Put dockerfile in place
       template:
         src: Dockerfile.j2
-        dest: "/opt/{{ docker_service }}/Dockerfile"
+        dest: "{{ docker_build_directory }}/Dockerfile"
         mode: 0644
 
     - name: Build docker image for {{ docker_service }}
@@ -16,7 +25,7 @@
         force_source: true
         build:
           pull: true
-          path: "/opt/{{ docker_service }}"
+          path: "{{ docker_build_directory }}"
       register: built_image
 
 - name: Pull container image for {{ docker_service }}