chore: initial commit

lib/system/default.nix

@@ -0,0 +1,201 @@
+{ core-inputs
+, user-inputs
+, snowfall-lib
+}:
+
+let
+  inherit (builtins) dirOf baseNameOf;
+  inherit (core-inputs.nixpkgs.lib) assertMsg fix hasInfix concatMap foldl;
+
+  virtual-systems = import ./virtual-systems.nix;
+
+  user-systems-root = snowfall-lib.fs.get-file "systems";
+  user-modules-root = snowfall-lib.fs.get-file "modules";
+
+  get-inferred-system-name = path:
+    if snowfall-lib.path.has-file-extension "nix" path then
+      snowfall-lib.path.get-parent-directory path
+    else
+      baseNameOf path;
+in
+{
+  system = rec {
+    # Check whether a named system is macOS.
+    # Type: String -> Bool
+    # Usage: is-darwin "x86_64-linux"
+    #   result: false
+    is-darwin = hasInfix "darwin";
+
+    # Check whether a named system is Linux.
+    # Type: String -> Bool
+    # Usage: is-linux "x86_64-linux"
+    #   result: false
+    is-linux = hasInfix "linux";
+
+    # Get the virtual system type of a system target.
+    # Type: String -> String
+    # Usage: get-virtual-system-type "x86_64-iso"
+    #   result: "iso"
+    get-virtual-system-type = target:
+      foldl
+        (result: virtual-system:
+          if result == "" && hasInfix virtual-system target then
+            virtual-system
+          else
+            result
+        )
+        ""
+        virtual-systems;
+
+    # Get structured data about all systems for a given target.
+    # Type: String -> [Attrs]
+    # Usage: get-target-systems-metadata "x86_64-linux"
+    #   result: [ { target = "x86_64-linux"; name = "my-machine"; path = "/systems/x86_64-linux/my-machine"; } ]
+    get-target-systems-metadata = target:
+      let
+        systems = snowfall-lib.fs.get-directories target;
+        existing-systems = builtins.filter (system: builtins.pathExists "${system}/default.nix") systems;
+        create-system-metadata = path: {
+          path = "${path}/default.nix";
+          # We are building flake outputs based on file contents. Nix doesn't like this
+          # so we have to explicitly discard the string's path context to allow us to
+          # use the name as a variable.
+          name = builtins.unsafeDiscardStringContext (builtins.baseNameOf path);
+          # We are building flake outputs based on file contents. Nix doesn't like this
+          # so we have to explicitly discard the string's path context to allow us to
+          # use the name as a variable.
+          target = builtins.unsafeDiscardStringContext (builtins.baseNameOf target);
+        };
+        system-configurations = builtins.map create-system-metadata existing-systems;
+      in
+      system-configurations;
+
+    # Get the system builder for a given target.
+    # Type: String -> Function
+    # Usage: get-system-builder "x86_64-iso"
+    #   result: (args: <system>)
+    get-system-builder = target:
+      let
+        virtual-system-type = get-virtual-system-type target;
+        virtual-system-builder = args:
+          assert (assertMsg (user-inputs ? nixos-generators) "In order to create virtual systems, you must include `nixos-generators` as a flake input.");
+          user-inputs.nixos-generators.nixosGenerate
+            (args // {
+              format = virtual-system-type;
+              specialArgs = args.specialArgs // {
+                format = virtual-system-type;
+              };
+            });
+        darwin-system-builder = args:
+          assert (assertMsg (user-inputs ? darwin) "In order to create virtual systems, you must include `darwin` as a flake input.");
+          user-inputs.darwin.lib.darwinSystem ((builtins.removeAttrs args [ "system" ]) // {
+            specialArgs = args.specialArgs // {
+              format = "darwin";
+            };
+          });
+        linux-system-builder = args:
+          core-inputs.nixpkgs.lib.nixosSystem
+            (args // {
+              specialArgs = args.specialArgs // {
+                format = "linux";
+              };
+            });
+      in
+      if virtual-system-type != "" then
+        virtual-system-builder
+      else if is-darwin target then
+        darwin-system-builder
+      else
+        linux-system-builder;
+
+    # Get the flake output attribute for a system target.
+    # Type: String -> String
+    # Usage: get-system-output "aarch64-darwin"
+    #   result: "darwinConfigurations"
+    get-system-output = target:
+      let
+        virtual-system-type = get-virtual-system-type target;
+      in
+      if virtual-system-type != "" then
+        "${virtual-system-type}Configurations"
+      else if is-darwin target then
+        "darwinConfigurations"
+      else
+        "nixosConfigurations";
+
+    # Get the resolved (non-virtual) system target.
+    # Type: String -> String
+    # Usage: get-resolved-system-target "x86_64-iso"
+    #   result: "x86_64-linux"
+    get-resolved-system-target = target:
+      let
+        virtual-system-type = get-virtual-system-type target;
+      in
+      if virtual-system-type != "" then
+        builtins.replaceStrings [ virtual-system-type ] [ "linux" ] target
+      else
+        target;
+
+    # Create a system.
+    # Type: Attrs -> Attrs
+    # Usage: create-system { path = ./systems/my-system; }
+    #   result: <flake-utils-plus-system-configuration>
+    create-system =
+      { target ? "x86_64-linux"
+      , system ? get-resolved-system-target target
+      , path
+      , name ? builtins.unsafeDiscardStringContext (get-inferred-system-name path)
+      , modules ? [ ]
+      , specialArgs ? { }
+      , channelName ? "nixpkgs"
+      , builder ? get-system-builder target
+      , output ? get-system-output target
+      , systems ? { }
+      }:
+      let
+        lib = snowfall-lib.internal.system-lib;
+      in
+      # (lib.traceSeqN 1 path)
+      {
+        inherit channelName system builder output;
+
+        modules = [ path ] ++ modules;
+
+        specialArgs = specialArgs // {
+          inherit system name systems lib;
+
+          inputs = snowfall-lib.flake.without-src user-inputs;
+        };
+      };
+
+    # Create all available systems.
+    # Type: Attrs -> Attrs
+    # Usage: create-systems { hosts.my-host.specialArgs.x = true; modules = [ my-shared-module ]; }
+    #   result: { my-host = <flake-utils-plus-system-configuration>; }
+    create-systems = systems:
+      let
+        targets = snowfall-lib.fs.get-directories user-systems-root;
+        target-systems-metadata = concatMap get-target-systems-metadata targets;
+        user-modules = snowfall-lib.fs.get-default-nix-files-recursive user-modules-root;
+        create-system' = created-systems: system-metadata:
+          let
+            overrides = systems.hosts.${system-metadata.name} or { };
+          in
+          {
+            ${system-metadata.name} = create-system (overrides // system-metadata // {
+              systems = created-systems;
+              modules = user-modules ++ (overrides.modules or [ ]) ++ (systems.modules or [ ]);
+            });
+          };
+        created-systems = fix (created-systems:
+          foldl
+            (systems: system-metadata:
+              systems // (create-system' created-systems system-metadata)
+            )
+            { }
+            target-systems-metadata
+        );
+      in
+      created-systems;
+  };
+}

lib/system/virtual-systems.nix

@@ -0,0 +1,34 @@
+# @NOTE(jakehamilton): The order of these entries matters. We search them
+# from start to finish and only match based on whether they appear in a
+# system target. This means that entries like "vm" would match all cases
+# of "vm-bootloader", "vm-no-gui", and "vmware". To avoid this mismatch,
+# entries should be ordered from most-specific to least-specific.
+[
+  "amazon"
+  "azure"
+  "cloudstack"
+  "do"
+  "gce"
+  "hyperv"
+  "install-iso-hyperv"
+  "install-iso"
+  "iso"
+  "kexec"
+  "kexec-bundle"
+  "kubevirt"
+  "lxc-metadata"
+  "lxc"
+  "openstack"
+  "proxmox"
+  "qcow"
+  "raw"
+  "raw-efi"
+  "sd-aarch64-installer"
+  "sd-aarch64"
+  "vagrant-virtualbox"
+  "virtualbox"
+  "vm-bootloader"
+  "vm-nogui"
+  "vmware"
+  "vm"
+]