nixos/virtualisation/nspawn-container: add virtualisation.credentials support

Assisted-by: Claude <noreply@anthropic.com>

nixos/modules/virtualisation/credentials-options.nix

@@ -0,0 +1,63 @@
+{ lib, pkgs, ... }:
+{
+  options.virtualisation.credentials = lib.mkOption {
+    description = ''
+      Credentials to pass to the VM or container using systemd's credential system.
+
+      See {manpage}`systemd.exec(5)`, {manpage}`systemd-creds(1)` and https://systemd.io/CREDENTIALS/ for more
+      information about systemd credentials.
+    '';
+    default = { };
+    example = lib.literalExpression ''
+      {
+        database-password = {
+          text = "my-secret-password";
+        };
+        ssl-cert = {
+          source = "./cert.pem";
+        };
+        binary-key = {
+          source = "./private.der";
+        };
+      }
+    '';
+    type = lib.types.attrsOf (
+      lib.types.submodule (
+        {
+          name,
+          options,
+          config,
+          ...
+        }:
+        {
+          options = {
+            source = lib.mkOption {
+              type = lib.types.nullOr (lib.types.pathWith { });
+              default = null;
+              description = ''
+                Source file on the host containing the credential data.
+              '';
+            };
+            text = lib.mkOption {
+              default = null;
+              type = lib.types.nullOr lib.types.str;
+              description = ''
+                Text content of the credential.
+
+                For binary data or when the credential content should come from
+                an existing file, use `source` instead.
+
+                ::: {.warning}
+                The text here is stored in the host's nix store as a file.
+                :::
+              '';
+            };
+          };
+          config.source = lib.mkIf (config.text != null) (
+            lib.mkDerivedConfig options.text (pkgs.writeText name)
+          );
+        }
+      )
+    );
+  };
+}

nixos/modules/virtualisation/nspawn-container/default.nix

@@ -21,6 +21,10 @@ let
   cfg = config.virtualisation;
 in
 {
+  imports = [
+    ../credentials-options.nix
+  ];
+
   options = {
 
     virtualisation.cmdline = lib.mkOption {
@@ -131,7 +135,8 @@ in
 
       # Send a READY=1 notification to a socket when the container is fully booted.
       "--notify-ready=yes"
-    ];
+    ]
+    ++ lib.mapAttrsToList (name: cred: "--load-credential=${name}:${cred.source}") cfg.credentials;
 
     system.build.nspawn =
       let

nixos/modules/virtualisation/qemu-vm.nix

@@ -399,6 +399,7 @@ in
   imports = [
     ../profiles/qemu-guest.nix
     ./disk-size-option.nix
+    ./credentials-options.nix
     (mkRenamedOptionModule
       [
         "virtualisation"
@@ -1126,81 +1127,20 @@ in
     };
 
     virtualisation.credentials = mkOption {
-      description = ''
-        Credentials to pass to the VM using systemd's credential system.
-
-        See {manpage}`systemd.exec(5)` , {manpage}`systemd-creds(1)` and https://systemd.io/CREDENTIALS/ for more
-        information about systemd credentials.
-      '';
-      default = { };
-      example = {
-        database-password = {
-          text = "my-secret-password";
-        };
-        ssl-cert = {
-          source = "./cert.pem";
-        };
-        binary-key = {
-          mechanism = "fw_cfg";
-          source = "./private.der";
-        };
-        config-file = {
-          mechanism = "smbios";
-          text = ''
-            [database]
-            host=localhost
-            port=5432
-          '';
-        };
-      };
       type = types.attrsOf (
-        lib.types.submodule (
-          {
-            name,
-            options,
-            config,
-            ...
-          }:
-          {
-            options = {
-              mechanism = lib.mkOption {
-                type = lib.types.enum [
-                  "fw_cfg"
-                  "smbios"
-                ];
-                default = if pkgs.stdenv.hostPlatform.isx86 then "smbios" else "fw_cfg";
-                defaultText = lib.literalExpression ''if pkgs.stdenv.hostPlatform.isx86 then "smbios" else "fw_cfg"'';
-                description = ''
-                  The mechanism used to pass the credential to the VM.
-                '';
-              };
-              source = lib.mkOption {
-                type = lib.types.nullOr (lib.types.pathWith { });
-                default = null;
-                description = ''
-                  Source file on the host containing the credential data.
-                '';
-              };
-              text = lib.mkOption {
-                default = null;
-                type = lib.types.nullOr lib.types.str;
-                description = ''
-                  Text content of the credential.
-
-                  For binary data or when the credential content should come from
-                  an existing file, use `source` instead.
-
-                  ::: {.warning}
-                  The text here is stored in the host's nix store as a file.
-                  :::
-                '';
-              };
-            };
-            config.source = lib.mkIf (config.text != null) (
-              lib.mkDerivedConfig options.text (pkgs.writeText name)
-            );
-          }
-        )
+        lib.types.submodule {
+          options.mechanism = lib.mkOption {
+            type = lib.types.enum [
+              "fw_cfg"
+              "smbios"
+            ];
+            default = if pkgs.stdenv.hostPlatform.isx86 then "smbios" else "fw_cfg";
+            defaultText = lib.literalExpression ''if pkgs.stdenv.hostPlatform.isx86 then "smbios" else "fw_cfg"'';
+            description = ''
+              The mechanism used to pass the credential to the VM.
+            '';
+          };
+        }
       );
     };