container: make dockerfile variable officially supported and more modular

roles/container/defaults/main.yml

@@ -3,6 +3,7 @@
 docker_host_user: false
 docker_volume_type: named
 docker_mariadb_config: {}
+dockerfile: []
 
 docker_phpmyadmin_basicauth: true
 docker_phpmyadmin_basicauth_users: {}

roles/container/meta/argument_specs.yml

@@ -17,6 +17,12 @@ argument_specs:
         description: "Docker image to use for the container. If dockerfile is defined, it will be used as base for locally built image (example: gitea/gitea:latest)"
         type: str
         required: true
+      dockerfile:
+        description: "A list of dockerfile instructions to add to the base image"
+        type: list
+        elements: str
+        required: false
+        default: []
       docker_host_user:
         description: "If true, creates a user on the host for this service. The container will run as this user's uid/gid. Bind mount volumes will be owned by this user."
         type: bool

roles/container/tasks/init.yml

@@ -39,7 +39,7 @@
   set_fact:
     template_mounts_needed: "{{ docker_mounts | selectattr('template', 'defined') | list | length > 0 }}"
     volumes_needed: "{{ docker_mounts | selectattr('name', 'defined') | list | length > 0 or docker_database != 'none' }}"
-    dockerfile_needed: "{{ dockerfile is defined and dockerfile | length > 0 }}"
+    dockerfile_needed: "{{ dockerfile | length > 0 }}"
     db_config_mounts_needed: "{{ docker_mariadb_config | length > 0 }}"
 - name: Set more assistive variables
   set_fact:

roles/container/templates/Dockerfile.j2

@@ -1,9 +1,6 @@
 # {{ ansible_managed }}
 
 FROM {{ docker_image }}
-{% if dockerfile.run is iterable %}
-{% for cmd in dockerfile.run %}
-RUN {{ cmd }}
+{% for item in dockerfile %}
+{{ item }}
 {% endfor %}
-{% endif %}
-