inventory: Add roles.<name>.description option and a warning if it is not set

clanServices/borgbackup/default.nix

@@ -9,7 +9,7 @@
   # TODO: a client can only be in one instance, add constraint
 
   roles.server = {
-
+    description = "A borgbackup server that stores the backups of clients.";
     interface =
       { lib, ... }:
       {
@@ -62,6 +62,7 @@
   };
 
   roles.client = {
+    description = "A borgbackup client that backs up to one or more borgbackup servers.";
     interface =
       {
         lib,

lib/modules/inventory/distributed-service/inventory-adapter.nix

@@ -140,6 +140,12 @@
               imports = [
                 # Import the resolved module.
                 # i.e. clan.modules.admin
+                {
+                  options.module = lib.mkOption {
+                    type = lib.types.raw;
+                    default = (builtins.head instances).instance.module;
+                  };
+                }
                 (builtins.head instances).instance.resolvedModule
               ] # Include all the instances that correlate to the resolved module
               ++ (builtins.map (v: {

lib/modules/inventory/distributed-service/service-module.nix

@@ -381,6 +381,13 @@ in
                 roleName = name;
               in
               {
+                options.description = mkOption {
+                  type = lib.types.nullOr types.str;
+                  description = "A short description of the role '${name}', explaining it's effect on the supplied machine.";
+                  example = "Connects the supplied machine as a '${name}' to the 'example' service.";
+                  default = null;
+                };
+
                 options.interface = mkOption {
                   description = ''
                     Abstract interface of the role.
@@ -959,8 +966,21 @@ in
               (
                 let
                   failedAssertions = (lib.filterAttrs (_: v: !v.assertion) config.result.assertions);
+                  formatModule =
+                    if config.module.input != null then
+                      "${config.module.input}/${config.module.name}"
+                    else
+                      "<clan-core>/${config.module.name}";
+                  warningsWithNull = lib.mapAttrsToList (
+                    roleName: roleConfig:
+                    if (roleConfig.description == null) then
+                      "Missing description for role '${roleName}' of clanService '${formatModule}'"
+                    else
+                      null
+                  ) config.roles;
                 in
                 {
+                  warnings = (lib.filter (v: v != null) warningsWithNull);
                   assertions = lib.attrValues failedAssertions;
                 }
               )

lib/modules/inventoryClass/service-list-from-inputs.nix

@@ -19,7 +19,7 @@ let
     in
     {
       manifest = eval.config.manifest;
-      roles = lib.mapAttrs (_n: _v: { }) eval.config.roles;
+      roles = lib.mapAttrs (_n: v: { inherit (v) description; }) eval.config.roles;
     };
 in
 {

pkgs/clan-app/ui/src/workflows/Service/Service.stories.tsx

@@ -37,8 +37,14 @@ const mockFetcher: Fetcher = <K extends OperationNames>(
               description: "This is module A",
             },
             roles: {
-              client: null,
-              server: null,
+              client: {
+                name: "client",
+                description: null,
+              },
+              server: {
+                name: "server",
+                description: null,
+              },
             },
           },
         },
@@ -52,9 +58,18 @@ const mockFetcher: Fetcher = <K extends OperationNames>(
               description: "This is module B",
             },
             roles: {
-              peer: null,
-              moon: null,
-              controller: null,
+              peer: {
+                name: "peer",
+                description: null,
+              },
+              moon: {
+                name: "moon",
+                description: null,
+              },
+              controller: {
+                name: "controller",
+                description: null,
+              },
             },
           },
         },

pkgs/clan-cli/clan_lib/services/modules.py

@@ -147,10 +147,16 @@ def extract_frontmatter[T](
     )
 
 
+@dataclass(frozen=True, eq=True)
+class Role:
+    name: str
+    description: str | None = None
+
+
 @dataclass
 class ModuleInfo:
     manifest: ModuleManifest
-    roles: dict[str, None]
+    roles: dict[str, Role]
 
 
 @dataclass
@@ -242,6 +248,9 @@ def list_service_modules(flake: Flake) -> ClanModules:
                     "input": None if input_name == clan_input_name else input_name,
                 }
             )
+
+            roles = module_info.get("roles", {})
+
             res.append(
                 Module(
                     instance_refs=find_instance_refs_for_module(
@@ -249,7 +258,13 @@ def list_service_modules(flake: Flake) -> ClanModules:
                     ),
                     usage_ref=module_ref,
                     info=ModuleInfo(
-                        roles=module_info.get("roles", {}),
+                        roles={
+                            rname: Role(
+                                name=rname,
+                                description=roles[rname].get("description", None),
+                            )
+                            for rname in roles
+                        },
                         manifest=ModuleManifest.from_dict(module_info["manifest"]),
                     ),
                     native=(input_name == clan_input_name),
@@ -462,7 +477,8 @@ def set_service_instance(
         raise ClanError(msg)
 
     module = resolve_service_module_ref(flake, module_ref)
-    allowed_roles = module.info.roles.keys()
+
+    allowed_roles = list(module.info.roles)
 
     for role_name in roles:
         if role_name not in allowed_roles:

pkgs/clan-cli/clan_lib/services/modules_test.py

@@ -62,6 +62,13 @@ def test_list_service_instances(
     assert instances["baz"].resolved.usage_ref.get("input") is None
     assert instances["baz"].resolved.usage_ref.get("name") == "sshd"
 
+    borgbackup_service = next(
+        m for m in service_modules.modules if m.usage_ref.get("name") == "borgbackup"
+    )
+    # Module has roles with descriptions
+    assert borgbackup_service.info.roles["client"].description is not None
+    assert borgbackup_service.info.roles["server"].description is not None
+
 
 @pytest.mark.with_core
 def test_list_service_modules(