The system output usually contains a symlink from /etc to the static configuration for the benefit of the stage-1 script in the initrd. The stage-2 script is usually started in the real root without such a symlink. In a container, there is no stage-1 and the system output is used directly as a real root. If the symlink is present, setup-etc.pl will create a symlink cycle and the system cannot boot. There is no reason for the /etc link to exist in a container because setup-etc.pl will create the necessary files. The container module will now remove the /etc symlink and create an empty directory. The empty /etc is for container managers to populate it with site-specific settings; for example, to set the hostname. This is required to boot NixOS in an LXC container on another host. See also: #9735
		
			
				
	
	
		
			62 lines
		
	
	
		
			1.5 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			62 lines
		
	
	
		
			1.5 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ config, lib, pkgs, ... }:
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with lib;
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let inherit (pkgs) writeScript; in
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let
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 pkgs2storeContents = l : map (x: { object = x; symlink = "none"; }) l;
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in {
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  # Docker image config.
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  imports = [
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    ../installer/cd-dvd/channel.nix
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    ./minimal.nix
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    ./clone-config.nix
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  ];
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  # Create the tarball
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  system.build.tarball = pkgs.callPackage ../../lib/make-system-tarball.nix {
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    contents = [
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      {
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        source = "${config.system.build.toplevel}/.";
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        target = "./";
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      }
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    ];
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    extraArgs = "--owner=0";
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    # Add init script to image
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    storeContents = pkgs2storeContents [
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      config.system.build.toplevel
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      pkgs.stdenv
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    ];
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    # Some container managers like lxc need these
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    extraCommands =
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      let script = writeScript "extra-commands.sh" ''
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            rm etc
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            mkdir -p proc sys dev etc
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          '';
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      in script;
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  };
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  boot.isContainer = true;
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  boot.postBootCommands =
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    ''
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      # After booting, register the contents of the Nix store in the Nix
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      # database.
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      if [ -f /nix-path-registration ]; then
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        ${config.nix.package.out}/bin/nix-store --load-db < /nix-path-registration &&
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        rm /nix-path-registration
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      fi
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      # nixos-rebuild also requires a "system" profile
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      ${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/system --set /run/current-system
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    '';
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  # Install new init script
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  system.activationScripts.installInitScript = ''
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    ln -fs $systemConfig/init /init
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  '';
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}
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