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Merge pull request #227881 from NixOS/qemu-vm/mount-host-nix-store

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nixos/qemu-vm: introduce `virtualisation.mountHostNixStore` option
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Ryan Lahfa 2023-04-24 19:39:54 +02:00 committed by GitHub
parent 0afeb09b63 0df5257b82
commit 7812abd3d0
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 20 additions and 2 deletions
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22
nixos/modules/virtualisation/qemu-vm.nix
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@ -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";
};