diff --git a/deployment/data-model-test.nix b/deployment/data-model-test.nix
index 64cfaf0d..0deeb563 100644
--- a/deployment/data-model-test.nix
+++ b/deployment/data-model-test.nix
@@ -50,9 +50,12 @@ in
                 };
               };
             };
-            migrations.boo = {
-              deployment = config.deployments.baz;
-              runtime-environment = config.resources.bar.runtime-environment;
+            environments.single-nixos-vm = {
+
+            };
+            configurations.example = {
+              enable = true;
+              applications.hello.enable = true;
             };
           }
         );
diff --git a/deployment/data-model.nix b/deployment/data-model.nix
index b6348b03..de58f351 100644
--- a/deployment/data-model.nix
+++ b/deployment/data-model.nix
@@ -105,8 +105,10 @@ in
             resource-mapping = mkOption {
               description = "Mapping of resources required by applications to available resources; the result can be deployed";
               type = environment.config.function.implementation;
-              # TODO: type = consumer-resources /* same as the output of application.config-mapping, should be in a `let` */ -> nixops4Deployment
             };
+            # TODO: somewhere we still need to
+            # - apply = { implementation = resource-mapping; input = <resource requirements of configured applications>; }
+            # - apply.output (deployment)
             function = mkOption {
               description = "Function type for the mapping from resources to a (NixOps4) deployment";
               type = submodule functionType;
@@ -120,5 +122,17 @@ in
         })
       );
     };
+    configurations = mkOption {
+      description = "Application configurations set by operators";
+      type = attrsOf (submodule {
+        options = {
+          enable = mkOption {
+            description = "Whether to enable the configuration";
+            type = types.bool;
+          };
+          applications = mapAttrs (name: application: submodule application.module) config.applications;
+        };
+      });
+    };
   };
 }