service: Support setting container secrets

roles/service/meta/argument_specs.yaml

@@ -66,6 +66,23 @@ argument_specs:
             type: bool
             required: false
             default: false
+      service_container_secrets:
+        description: A list of secrets available to the service container in /run/secrets/<service name>-<secret name>
+        type: list
+        required: false
+        default: []
+        elements: dict
+        options:
+          name:
+            description: Name of the secret
+            type: str
+            required: true
+          value:
+            description:
+              - Value of the secret. Defaults to a 128-character random string containing alphanumeric characters.
+              - If the value is not explicitly set, it will not be changed if the secret already exists.
+            type: str
+            required: false
       service_container_env:
         description: A dict of environment variables for the service container(s)
         type: dict