container, service: Support reloading containers on template file change

roles/service/meta/argument_specs.yaml

@@ -298,6 +298,26 @@ argument_specs:
         default: []
         elements: str
 
+      service_container_reload_method:
+        description: |
+          How to reload configuration when systemctl reload is called
+          kill: Sends SIGHUP to the container
+          command: Runs the specified command inside the container
+        type: str
+        required: false
+        default: none
+        choices:
+          - kill
+          - command
+          - none
+      service_container_reload_command:
+        description: >-
+          Command to run inside container when systemctl reload is called.
+          Required if container_reload_method is command, ignored otherwise.
+        type: str
+        required: false
+        default: ""
+
       service_database_type:
         description:
           - Database type to set up.
@@ -553,6 +573,25 @@ argument_specs:
             type: list
             required: false
             elements: str
+          reload_method:
+            description: |
+              How to reload configuration when systemctl reload is called
+              kill: Sends SIGHUP to the container
+              command: Runs the specified command inside the container
+            type: str
+            required: false
+            default: none
+            choices:
+              - kill
+              - command
+              - none
+          reload_command:
+            description: >-
+              Command to run inside container when systemctl reload is called.
+              Required if container_reload_method is command, ignored otherwise.
+            type: str
+            required: false
+            default: ""
           secrets:
             description:
               - >