add support for system-manager

docs/folder-structure.md

@@ -59,7 +59,7 @@ pkgs.mkShell {
 }
 ```
 
-### `hosts/<hostname>/(default.nix|configuration.nix|darwin-configuration.nix)`
+### `hosts/<hostname>/(default.nix|configuration.nix|darwin-configuration.nix,system-configuration.nix)`
 
 Each folder contains either a NixOS or nix-darwin configuration:
 
@@ -123,6 +123,31 @@ Flake outputs:
 * `darwinConfiguration.<hostname>`
 * `checks.<system>.darwin-<hostname>` - contains the system closure.
 
+#### `system-configuration.nix`
+
+Evaluates to a [system-manager](https://github.com/numtide/system-manager)
+configuration.
+
+To support it, also add the following lines to the `flake.nix` file:
+
+```nix
+{
+  inputs.system-manager.url = "github:numtide/system-manager";
+}
+```
+
+Additional values passed:
+
+* `inputs` maps to the current flake inputs.
+* `flake` maps to `inputs.self`.
+* `perSystem`: contains the packages of all the inputs, filtered per system.
+    Eg: `perSystem.nixos-anywhere.default` is a shorthand for `inputs.nixos-anywhere.packages.<system>.default`.
+
+Flake outputs:
+
+* `systemConfiguration.<hostname>`
+* `checks.<system>.system-<hostname>` - contains the system closure.
+
 #### `default.nix`
 
 If present, this file takes precedence over `configuration.nix` and `darwin-configuration.nix` and is designed as an

lib/default.nix

@@ -298,6 +298,24 @@ let
               };
             };
 
+          loadSystemManager =
+            _hostname: path:
+            let
+              system-manager =
+                inputs.system-manager
+                  or (throw ''${path} depends on system-manager. To fix this, add `inputs.system-manager.url = "github:numtide/system-manager"; to your flake'');
+            in
+            {
+              class = "system-manager";
+              value = system-manager.lib.makeSystemConfig {
+                modules = [
+                  perSystemModule
+                  path
+                ];
+                extraSpecialArgs = specialArgs;
+              };
+            };
+
           loadHost =
             name:
             { path, type }:
@@ -307,6 +325,8 @@ let
               loadNixOS name (path + "/configuration.nix")
             else if builtins.pathExists (path + "/darwin-configuration.nix") then
               loadNixDarwin name (path + "/darwin-configuration.nix")
+            else if builtins.pathExists (path + "/system-configuration.nix") then
+              loadSystemManager name (path + "/system-configuration.nix")
             else if builtins.hasAttr name homesNested then
               # If there are any home configurations defined for this host, they
               # must be standalone configurations since there is no OS config.
@@ -327,6 +347,8 @@ let
             "nixosConfigurations"
           else if x.value.class == "nix-darwin" then
             "darwinConfigurations"
+          else if x.value.class == "system-manager" then
+            "systemConfigs"
           else
             throw "host '${x.name}' of class '${x.value.class or "unknown"}' not supported"
         ) (lib.attrsToList hosts)
@@ -466,6 +488,7 @@ let
 
       darwinConfigurations = lib.mapAttrs (_: x: x.value) (hostsByCategory.darwinConfigurations or { });
       nixosConfigurations = lib.mapAttrs (_: x: x.value) (hostsByCategory.nixosConfigurations or { });
+      systemConfigs = lib.mapAttrs (_: x: x.value) (hostsByCategory.systemConfigs or { });
 
       inherit modules;
 
@@ -522,6 +545,12 @@ let
                 lib.filterAttrs (_: x: x.pkgs.system == system) (inputs.self.darwinConfigurations or { })
               )
             ))
+            # add system-manager closures to checks
+            (withPrefix "system-" (
+              lib.mapAttrs (_: x: x) (
+                lib.filterAttrs (_: x: x.system == system) (inputs.self.systemConfigs or { })
+              )
+            ))
             # load checks from the /checks folder. Those take precedence over the others.
             (filterPlatforms system (
               optionalPathAttrs (src + "/checks") (

templates/system-manager/flake.nix

@@ -0,0 +1,15 @@
+{
+  description = "blueprint+system-manager example";
+
+  # Add all your dependencies here
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-unstable";
+    blueprint.url = "github:numtide/blueprint";
+    blueprint.inputs.nixpkgs.follows = "nixpkgs";
+    system-manager.url = "github:numtide/system-manager";
+    system-manager.inputs.nixpkgs.follows = "nixpkgs";
+  };
+
+  # Load the blueprint
+  outputs = inputs: inputs.blueprint { inherit inputs; };
+}

templates/system-manager/hosts/myhost/system-configuration.nix

@@ -0,0 +1,14 @@
+{ pkgs, ... }:
+{
+  config = {
+    nixpkgs.hostPlatform = "x86_64-linux";
+
+    services.nginx.enable = true;
+
+    environment = {
+      systemPackages = [
+        pkgs.ripgrep
+      ];
+    };
+  };
+}