nixpkgs/nixos/modules/virtualisation/lxcfs.nix

# LXC Configuration

{ config, lib, pkgs, ... }:

let
  cfg = config.virtualisation.lxc.lxcfs;
in {
  meta = {
    maintainers = lib.teams.lxc.members;
  };

  ###### interface
  options.virtualisation.lxc.lxcfs = {
    enable =
      lib.mkOption {
        type = lib.types.bool;
        default = false;
        description = ''
          This enables LXCFS, a FUSE filesystem for LXC.
          To use lxcfs in include the following configuration in your
          container configuration:
          ```
          virtualisation.lxc.defaultConfig = "lxc.include = ''${pkgs.lxcfs}/share/lxc/config/common.conf.d/00-lxcfs.conf";
          ```
        '';
      };
  };

  ###### implementation
  config = lib.mkIf cfg.enable {
    systemd.services.lxcfs = {
      description = "FUSE filesystem for LXC";
      wantedBy = [ "multi-user.target" ];
      before = [ "lxc.service" ];
      restartIfChanged = false;
      serviceConfig = {
        ExecStartPre="${pkgs.coreutils}/bin/mkdir -p /var/lib/lxcfs";
        ExecStart="${pkgs.lxcfs}/bin/lxcfs /var/lib/lxcfs";
        ExecStopPost="-${pkgs.fuse}/bin/fusermount -u /var/lib/lxcfs";
        KillMode="process";
        Restart="on-failure";
      };
    };
  };
}