service: Use saner defaults for additional containers

roles/service/meta/argument_specs.yaml

@@ -340,9 +340,10 @@ argument_specs:
       service_additional_containers:
         description:
           - List of additional containers for the service.
-          - >
-            Will inherit most options from main service container. All options can be overridden
-            per-container.
+          - >-
+            If image is not specified, will use service container image and
+            inherit most options from main service container.
+          - All options can be overridden per-container.
         type: list
         required: false
         default: []
@@ -363,26 +364,30 @@ argument_specs:
             required: false
             default: "{{ service_container_image }}"
           user:
-            description: The UID to run as inside the container
+            description:
+              - The UID to run as inside the container.
+              - Defaults to <service_container_user> if same image, "" otherwise.
             type: str
             required: false
-            default: "{{ service_container_user }}"
           command:
-            description: Command to start the container with.
+            description:
+              - Command to start the container with.
+              - Defaults to <service_container_command> if same image, [] otherwise.
             type: list
             required: false
-            default: []
             elements: str
           entrypoint:
-            description: Entrypoint to use in the container
+            description:
+              - Entrypoint to use in the container
+              - Defaults to <service_container_entrypoint> if same image, "" otherwise.
             type: str
             required: false
-            default: ""
           mounts:
-            description: List of bind mounts or volumes to be mounted inside the container.
+            description:
+              - List of bind mounts or volumes to be mounted inside the container.
+              - Defaults to <service_container_mounts> if same image, [] otherwise.
             type: list
             required: false
-            default: "{{ service_container_mounts }}"
             elements: dict
             options:
               type:
@@ -450,10 +455,11 @@ argument_specs:
                 required: false
                 default: []
           devices:
-            description: List of devices to be added inside the container.
+            description:
+              - List of devices to be added inside the container.
+              - Defaults to <service_container_devices> if same image, [] otherwise.
             type: list
             required: false
-            default: "{{ service_container_devices }}"
             elements: dict
             options:
               source:
@@ -506,15 +512,17 @@ argument_specs:
                 type: int
                 required: false
           env:
-            description: A dict of environment variables for the container
+            description:
+              - A dict of environment variables for the container
+              - Defaults to <service_container_env> if same image, {} otherwise.
             type: dict
             required: false
-            default: "{{ service_container_env }}"
           add_capabilities:
-            description: List of capabilities to add to the container
+            description:
+              - List of capabilities to add to the container
+              - Defaults to <service_container_add_capabilities> if same image, [] otherwise.
             type: list
             required: false
-            default: "{{ service_container_add_capabilities }}"
             elements: str
           secrets:
             description:
@@ -525,9 +533,9 @@ argument_specs:
                 A dict of secrets and their values (including autogenerated values) is available as
                 `service_podman_secrets` for use in templates. This should only be used if the
                 container doesn't support reading the secret from file or environment variable.
+              - Defaults to <service_container_secrets> if same image, [] otherwise.
             type: list
             required: false
-            default: "{{ service_container_secrets }}"
             elements: dict
             options:
               name:

roles/service/tasks/additional.yaml

@@ -4,18 +4,18 @@
     name: container
   vars:
     container_name: "{{ _service_additional_container.name }}"
-    container_image: "{{ _service_additional_container.image | default(service_container_image) }}"
-    container_command: "{{ _service_additional_container.command | default([]) }}"
-    container_entrypoint: "{{ _service_additional_container.entrypoint | default('') }}"
-    container_user: "{{ _service_additional_container.user | default(service_container_user) }}"
+    container_image: "{{ _service_additional_container.image }}"
+    container_command: "{{ _service_additional_container.command }}"
+    container_entrypoint: "{{ _service_additional_container.entrypoint }}"
+    container_user: "{{ _service_additional_container.user }}"
     container_mounts: "{{ _service_additional_container_mounts }}"
-    container_devices: "{{ _service_additional_container.devices | default(service_container_devices) }}"
+    container_devices: "{{ _service_additional_container.devices }}"
     container_publish_ports: "{{ _service_additional_container_publish_ports }}"
     container_networks: "{{ _service_additional_container_networks }}"
     container_hostname: "{{ _service_additional_container.name | regex_replace('^' ~ service_name ~ '-', '') }}"
     container_secrets: "{{ _service_additional_container_secrets }}"
-    container_env: "{{ _service_additional_container.env | default(service_container_env) }}"
-    container_add_capabilities: "{{ _service_additional_container.add_capabilities | default(service_container_add_capabilities) }}"
+    container_env: "{{ _service_additional_container.env }}"
+    container_add_capabilities: "{{ _service_additional_container.add_capabilities }}"
     container_requires: "{{ _service_container_requires }}"
     container_wants: "{{ _service_additional_container_wants }}"
     container_auto_update: "{{ service_auto_update }}"

roles/service/vars/main/additional.yaml

@@ -1,9 +1,67 @@
 ---
+_service_additional_containers_with_default_image: >-
+  {{
+    ([{ 'image': service_container_image }] * service_additional_containers | length)
+    | zip(service_additional_containers)
+    | map('combine')
+  }}
+
+_service_additional_container_same_image_defaults:
+  user: "{{ service_container_user }}"
+  command: "{{ service_container_command }}"
+  entrypoint: "{{ service_container_entrypoint }}"
+  devices: "{{ service_container_devices }}"
+  env: "{{ service_container_env }}"
+  add_capabilities: "{{ service_container_add_capabilities }}"
+
+_service_additional_container_different_image_defaults:
+  user: ""
+  command: []
+  entrypoint: ""
+  mounts: []
+  devices: []
+  publish_ports: []
+  env: {}
+  add_capabilities: []
+  secrets: []
+
+_service_additional_same_image_containers: >-
+  {{
+    _service_additional_containers_with_default_image
+    | selectattr('image', '==', service_container_image)
+  }}
+
+_service_additional_different_image_containers: >-
+  {{
+    _service_additional_containers_with_default_image
+    | selectattr('image', '!=', service_container_image)
+  }}
+
 _service_additional_containers: >-
   {{
-    service_additional_containers
+    (
+      (
+        (
+          [_service_additional_container_same_image_defaults] *
+          (_service_additional_same_image_containers | length)
+        )
+        | zip(_service_additional_same_image_containers)
+        | map('combine')
+      ) +
+      (
+        (
+          [_service_additional_container_different_image_defaults] *
+          (_service_additional_different_image_containers | length)
+        )
+        | zip(_service_additional_different_image_containers)
+        | map('combine')
+      )
+    )
     | zip(
-         service_additional_containers
+        (
+          _service_additional_same_image_containers +
+          _service_additional_different_image_containers
+        )
         | map(attribute='name')
         | map('regex_replace', '^', service_name ~ '-')
         | map('community.general.dict_kv', 'name')
@@ -11,6 +69,7 @@ _service_additional_containers: >-
     | map('combine')
   }}
 
+
 _service_additional_container_wants: >-
   {{
     service_wants