move applications from config to options to actually type-check application configurations

deployment/applications/default.nix

@@ -0,0 +1,19 @@
+{
+  lib,
+  ...
+}:
+let
+  applications = [
+    "mastodon"
+  ];
+in
+{
+  options = lib.genAttrs applications (
+    k:
+    # TODO: how to type entries here to conform to some common structure?
+    lib.mkOption {
+      description = "configuration options for ${k}";
+      type = lib.types.submodule ./${k};
+    }
+  );
+}

deployment/applications/mastodon/default.nix

@@ -0,0 +1,19 @@
+{
+  config,
+  lib,
+  ...
+}:
+{
+  options =
+    {
+      fediversity.domain = lib.mkOption {
+        type = lib.types.str;
+        default = "fediversity.tld";
+      };
+    }
+    // import ../../../services/fediversity/sharedOptions.nix {
+      inherit config lib;
+      serviceName = "mastodon";
+      serviceDocName = "Mastodon";
+    };
+}

deployment/data-model-test.nix

@@ -34,16 +34,13 @@ in
                 authentication.password = "";
               };
             };
-            applications.foo.module =
-              { pkgs, ... }:
-              {
-                environment.systemPackages = [
-                  pkgs.hello
-                ];
-              };
             deployments.baz = {
-              module = { };
               inherit runtime-environment;
+              application-configuration = {
+                mastodon = {
+                  enable = true;
+                };
+              };
             };
             migrations.boo = {
               inherit runtime-environment;
@@ -55,14 +52,12 @@ in
       {
         has-provider = lib.isAttrs example.providers.ssh-host;
         has-resource = lib.isAttrs example.resources.bar.runtime-environment.ssh-host.module;
-        has-application = lib.isAttrs example.applications.foo.module;
+        has-deployment = example.deployments.baz.application-configuration.mastodon.enable == true;
-        has-deployment = lib.isAttrs example.deployments.baz.module;
         has-migration = lib.isAttrs example.migrations.boo.deployment;
       };
     expected = {
       has-provider = true;
       has-resource = true;
-      has-application = true;
       has-deployment = true;
       has-migration = true;
     };

deployment/data-model.nix

@@ -4,6 +4,7 @@
   ...
 }:
 let
+  applications = ./applications; # how to make this configurable?
   inherit (lib)
     attrNames
     mapAttrs
@@ -100,32 +101,16 @@ let
       type = runtime-environment;
     };
   };
-  application = submoduleWith {
-    description = "A Fediversity application";
-    modules = [
-      {
-        options = {
-          module = mkOption {
-            description = ''
-              The NixOS module to configure the application.
-            '';
-            type = deferredModule;
-          };
-        };
-      }
-    ];
-  };
   deployment = submoduleWith {
     description = "A deployment of a configuration of applications to a run-time environment";
     modules = [
       {
         options = {
-          # the `applications` option consists of configuration for the above applications
+          application-configuration = mkOption {
-          module = mkOption {
             description = ''
               Configuration to be deployed
             '';
-            type = deferredModule;
+            type = submodule applications;
           };
           runtime-environment = mkOption {
             description = "The run-time environment to deploy to";
@@ -163,10 +148,6 @@ in
       description = "Collection of resources for use in Fediversity applications";
       type = attrsOf resource;
     };
-    applications = mkOption {
-      description = "Collection of (available) Fediversity applications";
-      type = attrsOf application;
-    };
     deployments = mkOption {
       description = "Deployment of a configuration of applications to a run-time environment";
       type = attrsOf deployment;