Inventory: refactor build-inventory in more independent parts

lib/build-clan/module.nix

@@ -76,7 +76,7 @@ let
           (machines.${name} or { })
           # Inherit the inventory assertions ?
           # { inherit (mergedInventory) assertions; }
-          { imports = serviceConfigs.${name} or [ ]; }
+          { imports = serviceConfigs.machines.${name}.machineImports or []; }
           (
             {
               # Settings

lib/inventory/build-inventory/default.nix

@@ -42,55 +42,30 @@ let
     builtins.elem "inventory"
       (clan-core.lib.modules.getFrontmatter modulepath serviceName).features or [ ];
 
-  extendMachine =
-    { machineConfig, inventory }:
-    [
+  compileMachine =
+    { machineConfig }:
+    {
+      machineImports = [
         (lib.optionalAttrs (machineConfig.deploy.targetHost or null != null) {
           config.clan.core.networking.targetHost = machineConfig.deploy.targetHost;
         })
-      {
-        assertions = lib.foldlAttrs (
-          acc: serviceName: _serviceConfigs:
-          acc
-          ++ [
-            {
-              assertion = checkService inventory.modules.${serviceName} serviceName;
-              message = ''
-                Service ${serviceName} cannot be used in inventory. It does not declare the 'inventory' feature.
-
-
-                To allow it add the following to the beginning of the README.md of the module:
-
-                  ---
-                  ...
-
-                  features = [ "inventory" ]
-                  ---
-
-                Also make sure to test the module with the 'inventory' feature enabled.
-
-              '';
-            }
-          ]
-        ) [ ] inventory.services;
-      }
       ];
+      assertions = { };
+    };
 
-  mapMachineConfigToNixOSConfig =
+  compileServicesForMachine =
     # Returns a NixOS configuration for the machine 'machineName'.
     # Return Format: { imports = [ ... ]; config = { ... }; options = { ... } }
     {
       machineName,
-      machineConfig,
       inventory,
       directory,
     }:
+    let
+      compileServiceModules = serviceName: serviceConfigs: {
+        # TODO: Add other attributes
+        machineImports = (
           lib.foldlAttrs (
-      # [ Modules ], String, { ${instance_name} :: ServiceConfig }
-      initialServiceModules: serviceName: serviceConfigs:
-      initialServiceModules
-      # Collect service config
-      ++ (lib.foldlAttrs (
             # [ Modules ], String, ServiceConfig
             acc2: instanceName: serviceConfig:
 
@@ -187,30 +162,69 @@ let
               ]
             else
               acc2
-      ) [ ] (serviceConfigs))
-    ) [ ] inventory.services
-    # Global extension for each machine
-    ++ (extendMachine { inherit machineConfig inventory; });
+          ) [ ] (serviceConfigs)
+        );
+
+        assertions = lib.mapAttrs' (name: value: {
+          name = "checkservice.${serviceName}.${name}";
+          value = {
+            assertion = checkService inventory.modules.${serviceName} serviceName;
+            message = ''
+              Service ${serviceName} cannot be used in inventory. It does not declare the 'inventory' feature.
+
+
+              To allow it add the following to the beginning of the README.md of the module:
+
+                ---
+                ...
+
+                features = [ "inventory" ]
+                ---
+
+              Also make sure to test the module with the 'inventory' feature enabled.
+
+            '';
+          };
+        }) inventory.services;
+      };
+
+    in
+    lib.mapAttrs compileServiceModules inventory.services;
+
   /*
-    Returns a NixOS configuration for every machine in the inventory.
+    Returns a set with NixOS configuration for every machine in the inventory.
 
     machinesFromInventory :: Inventory -> { ${machine_name} :: NixOSConfiguration }
   */
   buildInventory =
     { inventory, directory }:
-    # For every machine in the inventory, build a NixOS configuration
-    # For each machine generate config, forEach service, if the machine is used.
-    builtins.mapAttrs (
+    {
+      machines = builtins.mapAttrs (
         machineName: machineConfig:
-      mapMachineConfigToNixOSConfig {
+        let
+          compiledServices = compileServicesForMachine {
             inherit
               machineName
-          machineConfig
               inventory
               directory
               ;
+          };
+          compiledMachine = compileMachine {
+            inherit
+              machineConfig
+              ;
+          };
+          machineImports =
+            compiledMachine.machineImports
+            ++ builtins.foldl' (acc: service: acc ++ service.machineImports) [ ] (
+              builtins.attrValues compiledServices
+            );
+        in
+        {
+          inherit machineImports compiledServices compiledMachine;
         }
       ) (inventory.machines or { });
+    };
 in
 {
   inherit buildInventory;