[HACK] simplify out requests arg to make test pass

`mapAttrs'` takes two args rather than a set, whereas if only the val
changes `mapAttrs (_: v: ...)` should do

default.nix

@@ -11,6 +11,7 @@ let
     ;
   inherit (pkgs) lib;
   inherit (import sources.flake-inputs) import-flake;
+  inputs = (import-flake { src = ./.; }).inputs;
   inherit ((import-flake { src = ./.; }).inputs) nixops4;
   panel = import ./panel { inherit sources system; };
   pre-commit-check =
@@ -78,6 +79,7 @@ in
   # re-export inputs so they can be overridden granularly
   # (they can't be accessed from the outside any other way)
   inherit
+    inputs
     sources
     system
     pkgs

deployment/data-model-test.nix

@@ -1,36 +1,119 @@
 let
   inherit (import ../default.nix { }) pkgs inputs;
   inherit (pkgs) lib;
-  inherit (lib) mkOption;
+  inherit (lib) mkOption types;
   eval =
     module:
     (lib.evalModules {
       specialArgs = {
         inherit inputs;
+        # to be passed to nixops4Deployment
+        resourceProviderSystem = builtins.currentSystem;
       };
       modules = [
         module
         ./data-model.nix
       ];
     }).config;
+  nixops4Deployment = import ./deployment.nix { inherit lib inputs; };
 in
 {
-  _class = "nix-unit";
-
   test-eval = {
     expr =
       let
         fediversity = eval (
           { config, ... }:
           {
+            _class = "fediversity-settings";
             config = {
+              resources.nixos-configuration = {
+                description = "An entire NixOS configuration";
+                request =
+                  { ... }:
+                  {
+                    _class = "fediversity-resource-request";
+                    options.config = mkOption {
+                      description = "Any options from NixOS";
+                    };
+                  };
+
+                policy =
+                  { config, ... }:
+                  {
+                    _class = "fediversity-resource-policy";
+
+                    options = {
+                      extra-config = mkOption {
+                        description = "Any options from NixOS";
+                      };
+                      apply = mkOption {
+                        type = with types; functionTo raw;
+                        default = requests: lib.mkMerge (requests ++ [ config.extra-config ]);
+                      };
+                    };
+                  };
+              };
+              resources.login-shell = {
+                _class = "fediversity-resource";
+                description = "The operator needs to be able to log into the shell";
+                request =
+                  { ... }:
+                  {
+                    _class = "fediversity-resource-request";
+                    options = {
+                      wheel = mkOption {
+                        description = "Whether the login user needs root permissions";
+                        type = types.bool;
+                        default = false;
+                      };
+                      packages = mkOption {
+                        description = "Packages that need to be available in the user environment";
+                        type = with types; attrsOf package;
+                      };
+                    };
+                  };
+                policy =
+                  { config, ... }:
+                  {
+                    _class = "fediversity-resource-policy";
+                    options = {
+                      username = mkOption {
+                        description = "Username for the operator";
+                        type = types.str; # TODO: use the proper constraints from NixOS
+                      };
+                      wheel = mkOption {
+                        description = "Whether to allow login with root permissions";
+                        type = types.bool;
+                        default = false;
+                      };
+                      apply = mkOption {
+                        type = with types; functionTo raw; # TODO: splice out the user type from NixOS
+                        default =
+                          requests:
+                          let
+                            # Filter out requests that need wheel if policy doesn't allow it
+                            validRequests = lib.filterAttrs (_name: req: !req.wheel || config.wheel) requests;
+                          in
+                          lib.optionalAttrs (validRequests != { }) {
+                            ${config.username} = {
+                              isNormalUser = true;
+                              packages = with lib; concatMapAttrs (_name: request: attrValues request.packages) validRequests;
+                              extraGroups = lib.optional config.wheel "wheel";
+                            };
+                          };
+                      };
+                    };
+                  };
+              };
               applications.hello =
                 { ... }:
                 {
+                  _class = "fediversity-application";
                   description = ''Command-line tool that will print "Hello, world!" on the terminal'';
                   module =
                     { ... }:
                     {
+                      _class = "fediversity-application-config";
                       options = {
                         enable = lib.mkEnableOption "Hello in the shell";
                       };
@@ -38,19 +121,60 @@ in
                   implementation =
                     cfg:
                     lib.optionalAttrs cfg.enable {
+                      _class = "fediversity-application-requirements";
                       dummy.login-shell.packages.hello = pkgs.hello;
                     };
                 };
+              environments.single-nixos-vm =
+                { config, ... }:
+                {
+                  _class = "fediversity-environment";
+                  resources.shell.login-shell.username = "operator";
+                  implementation =
+                    { ... }:
+                    # { providers, ... }:
+                    {
+                      # _class = "nixops4Deployment";
+                      # providers = {
+                      #   inherit (inputs.nixops4.modules.nixops4Provider) local;
+                      # };
+                      resources.the-machine = {
+                        _class = "nixops4Resource";
+                        # type = providers.local.exec;
+                        imports = [
+                          inputs.nixops4-nixos.modules.nixops4Resource.nixos
+                        ];
+                        nixos.module =
+                          { ... }:
+                          {
+                            _class = "nixos";
+                            users.users = config.resources.shell.login-shell.apply (
+                              # lib.filterAttrs (_name: value: value ? login-shell) requests
+                              lib.filterAttrs (_name: value: value ? login-shell) { }
+                            );
+                          };
+                      };
+                    };
+                };
             };
             options = {
               example-configuration = mkOption {
                 type = config.configuration;
                 readOnly = true;
                 default = {
+                  _class = "fediversity-configuration";
                   enable = true;
                   applications.hello.enable = true;
                 };
               };
+              example-deployment = mkOption {
+                type = types.submoduleWith {
+                  class = "nixops4Deployment";
+                  modules = [ nixops4Deployment ];
+                };
+                readOnly = true;
+                default = config.environments.single-nixos-vm.deployment config.example-configuration;
+              };
             };
           }
         );
@@ -59,12 +183,14 @@ in
         inherit (fediversity)
           example-configuration
           ;
+        has-deployment = lib.isAttrs fediversity.example-deployment.resources.the-machine;
       };
     expected = {
       example-configuration = {
         enable = true;
         applications.hello.enable = true;
       };
+      has-deployment = true;
     };
   };
 }

deployment/data-model.nix

@@ -1,6 +1,7 @@
 {
   lib,
   config,
+  inputs,
   ...
 }:
 let
@@ -9,13 +10,14 @@ let
     attrsOf
     attrTag
     deferredModuleWith
-    submodule
+    submoduleWith
     optionType
     functionTo
     ;
 
   functionType = import ./function.nix;
-  application-resources = {
+  application-requirements = {
+    _class = "fediversity-application-requirements";
     options.resources = mkOption {
       # TODO: maybe transpose, and group the resources by type instead
       type = attrsOf (
@@ -23,66 +25,174 @@ let
       );
     };
   };
+  nixops4Deployment = import ./deployment.nix { inherit lib inputs; };
 in
 {
-  _class = "nixops4Deployment";
-
+  _class = "fediversity-settings";
   options = {
+    resources = mkOption {
+      description = "Collection of deployment resources that can be required by applications and policed by hosting providers";
+      type = attrsOf (submoduleWith {
+        class = "fediversity-resource";
+        modules = [
+          (
+            { ... }:
+            {
+              options = {
+                description = mkOption {
+                  description = "Description of the resource to help application module authors and hosting providers to work with it";
+                  type = types.str;
+                };
+                request = mkOption {
+                  description = "Options for declaring resource requirements by an application, a description of how the resource is consumed or accessed";
+                  type = deferredModuleWith { staticModules = [ { _class = "fediversity-resource-request"; } ]; };
+                };
+                policy = mkOption {
+                  description = "Options for configuring the resource policy for the hosting provider, a description of how the resource is made available";
+                  type = submoduleWith {
+                    class = "fediversity-resource-policy";
+                    modules = [
+                      {
+                        options.apply = mkOption {
+                          description = "Apply the policy to a request";
+                        };
+                      }
+                    ];
+                  };
+                };
+              };
+            }
+          )
+        ];
+      });
+    };
     applications = mkOption {
       description = "Collection of Fediversity applications";
-      type = attrsOf (
-        submodule (application: {
-          _class = "fediversity-application";
-          options = {
-            description = mkOption {
-              description = "Description to be shown in the application overview";
-              type = types.str;
-            };
-            module = mkOption {
-              description = "Operator-facing configuration options for the application";
-              type = deferredModuleWith { staticModules = [ { _class = "fediversity-application-config"; } ]; };
-            };
-            implementation = mkOption {
-              description = "Mapping of application configuration to deployment resources, a description of what an application needs to run";
-              type = application.config.config-mapping.function-type;
-            };
-            resources = mkOption {
-              description = "Compute resources required by an application";
-              type = functionTo application.config.config-mapping.output-type;
-              readOnly = true;
-              default = input: (application.config.implementation input).output;
-            };
-            config-mapping = mkOption {
-              description = "Function type for the mapping from application configuration to required resources";
-              type = submodule functionType;
-              readOnly = true;
-              default = {
-                input-type = application.config.module;
-                output-type = application-resources;
+      type = attrsOf (submoduleWith {
+        class = "fediversity-application";
+        modules = [
+          (application: {
+            options = {
+              description = mkOption {
+                description = "Description to be shown in the application overview";
+                type = types.str;
+              };
+              module = mkOption {
+                description = "Operator-facing configuration options for the application";
+                type = deferredModuleWith { staticModules = [ { _class = "fediversity-application-config"; } ]; };
+              };
+              implementation = mkOption {
+                description = "Mapping of application configuration to deployment resources, a description of what an application needs to run";
+                type = application.config.config-mapping.function-type;
+              };
+              resources = mkOption {
+                description = "Compute resources required by an application";
+                type = functionTo application.config.config-mapping.output-type;
+                readOnly = true;
+                default = input: (application.config.implementation input).output;
+              };
+              config-mapping = mkOption {
+                description = "Function type for the mapping from application configuration to required resources";
+                type = submoduleWith {
+                  class = "module-function";
+                  modules = [ functionType ];
+                };
+                readOnly = true;
+                default = {
+                  input-type = application.config.module;
+                  output-type = application-requirements;
+                };
               };
             };
-          };
-        })
-      );
+          })
+        ];
+      });
+    };
+    environments = mkOption {
+      description = "Run-time environments for Fediversity applications to be deployed to";
+      type = attrsOf (submoduleWith {
+        class = "fediversity-environment";
+        modules = [
+          (environment: {
+            options = {
+              resources = mkOption {
+                description = ''
+                  Resources made available by the hosting provider, and their policies.
+
+                  Setting this is optional, but provides a place to declare that information for programmatic use in the resource mapping.
+                '';
+                # TODO: maybe transpose, and group the resources by type instead
+                type = attrsOf (
+                  attrTag (
+                    lib.mapAttrs (
+                      _name: resource:
+                      mkOption {
+                        type = submoduleWith {
+                          class = "fediversity-resource-policy";
+                          modules = [ resource.policy ];
+                        };
+                      }
+                    ) config.resources
+                  )
+                );
+              };
+              implementation = mkOption {
+                description = "Mapping of resources required by applications to available resources; the result can be deployed";
+                # type = environment.config.resource-mapping.output-type;
+              };
+              resource-mapping = mkOption {
+                description = "Function type for the mapping from resources to a (NixOps4) deployment";
+                type = submoduleWith {
+                  class = "module-function";
+                  modules = [ functionType ];
+                };
+                readOnly = true;
+                default = {
+                  input-type = application-requirements;
+                  output-type = nixops4Deployment;
+                };
+              };
+              deployment = mkOption {
+                description = "Generate a deployment from a configuration";
+                type = functionTo (submoduleWith {
+                  class = "nixops4Deployment";
+                  modules = [ environment.config.resource-mapping.output-type ];
+                });
+                readOnly = true;
+                default = _cfg: environment.config.implementation;
+
+              };
+            };
+          })
+        ];
+      });
     };
     configuration = mkOption {
       description = "Configuration type declaring options to be set by operators";
       type = optionType;
       readOnly = true;
-      default = submodule {
-        options = {
-          enable = lib.mkEnableOption {
-            description = "your Fediversity configuration";
-          };
-          applications = lib.mapAttrs (
-            _name: application:
-            mkOption {
-              description = application.description;
-              type = submodule application.module;
-              default = { };
-            }
-          ) config.applications;
-        };
+      default = submoduleWith {
+        class = "fediversity-configuration";
+        modules = [
+          {
+            options = {
+              enable = lib.mkEnableOption {
+                description = "your Fediversity configuration";
+              };
+              applications = lib.mapAttrs (
+                _name: application:
+                mkOption {
+                  description = application.description;
+                  type = submoduleWith {
+                    class = "fediversity-application-config";
+                    modules = [ application.module ];
+                  };
+                  default = { };
+                }
+              ) config.applications;
+            };
+          }
+        ];
       };
     };
   };

deployment/deployment.nix

@@ -0,0 +1,34 @@
+{
+  lib,
+  # inputs,
+  ...
+}:
+# let
+#   nixops4 = inputs.nixops4.outPath;
+# in
+
+# inputs.nixops4.modules.nixops4Deployment.default
+
+# import inputs.nixops4.modules.nixops4Deployment.default
+
+# resources: import inputs.nixops4.modules.nixops4Deployment.default {
+#   inherit lib config resources;
+#   # config = {
+#   #   type providers provider inputs outputsSkeleton resourceType
+#   # };
+# }
+
+# {
+#   imports = [
+#     "${nixops4}/nix/deployment/providers.nix"
+#     "${nixops4}/nix/deployment/resources.nix"
+#   ];
+# };
+
+# "${nixops4}/nix/deployment/resources.nix"
+
+{
+  options.resources = lib.mkOption {
+    type = lib.types.attrs;
+  };
+}

deployment/function.nix

@@ -13,6 +13,7 @@ let
 in
 {
   options = {
+    _class = "module-function";
     input-type = mkOption {
       type = deferredModule;
     };