Merge pull request #227881 from NixOS/qemu-vm/mount-host-nix-store (7812abd3) · Commits · nix / nixpkgs

nixos/modules/virtualisation/qemu-vm.nix

+20 −2

Original line number	Diff line number	Diff line
		@@ -574,12 +574,15 @@ in
		virtualisation.writableStore =
		mkOption {
		type = types.bool;
		default = true; # FIXME
		default = cfg.mountHostNixStore;
		defaultText = literalExpression "cfg.mountHostNixStore";
		description =
		lib.mdDoc ''
		If enabled, the Nix store in the VM is made writable by
		layering an overlay filesystem on top of the host's Nix
		store.

		By default, this is enabled if you mount a host Nix store.
		'';
		};

		@@ -713,6 +716,21 @@ in
		For applications which do a lot of reads from the store,
		this can drastically improve performance, but at the cost of
		disk space and image build time.

		As an alternative, you can use a bootloader which will provide you
		with a full NixOS system image containing a Nix store and
		avoid mounting the host nix store through
		{option}`virtualisation.mountHostNixStore`.
		'';
		};

		virtualisation.mountHostNixStore =
		mkOption {
		type = types.bool;
		default = !cfg.useNixStoreImage && !cfg.useBootLoader;
		defaultText = literalExpression "!cfg.useNixStoreImage && !cfg.useBootLoader";
		description = lib.mdDoc ''
		Mount the host Nix store as a 9p mount.
		'';
		};

		@@ -933,7 +951,7 @@ in
		virtualisation.additionalPaths = [ config.system.build.toplevel ];

		virtualisation.sharedDirectories = {
		nix-store = mkIf (!cfg.useNixStoreImage) {
		nix-store = mkIf cfg.mountHostNixStore {
		source = builtins.storeDir;
		target = "/nix/store";
		};