For instance, if time.timeZone is defined multiple times, you now get the error message: error: user-thrown exception: The unique option `time.timeZone' is defined multiple times, in `/etc/nixos/configurations/misc/eelco/x11vnc.nix' and `/etc/nixos/configuration.nix'. while previously you got: error: user-thrown exception: Multiple definitions of string. Only one is allowed for this option. and only an inspection of the stack trace gave a clue as to what option caused the problem.
		
			
				
	
	
		
			70 lines
		
	
	
		
			2.2 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			70 lines
		
	
	
		
			2.2 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ config, pkgs, ... }:
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with pkgs.lib;
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let
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  sysctlOption = mkOptionType {
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    name = "sysctl option value";
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    check = x: builtins.isBool x || builtins.isString x || builtins.isInt x;
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    merge = args: xs: last xs; # FIXME: hacky way to allow overriding in configuration.nix.
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  };
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in
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{
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  options = {
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    boot.kernel.sysctl = mkOption {
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      default = {};
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      example = {
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        "net.ipv4.tcp_syncookies" = false;
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        "vm.swappiness" = 60;
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      };
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      type = types.attrsOf sysctlOption;
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      description = ''
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        Runtime parameters of the Linux kernel, as set by
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        <citerefentry><refentrytitle>sysctl</refentrytitle>
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        <manvolnum>8</manvolnum></citerefentry>.  Note that sysctl
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        parameters names must be enclosed in quotes
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        (e.g. <literal>"vm.swappiness"</literal> instead of
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        <literal>vm.swappiness</literal>).  The value of each parameter
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        may be a string, integer or Boolean.
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      '';
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    };
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  };
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  config = {
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    environment.etc."sysctl.d/nixos.conf".text =
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      concatStrings (mapAttrsToList (n: v: "${n}=${if v == false then "0" else toString v}\n") config.boot.kernel.sysctl);
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    systemd.services.systemd-sysctl =
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      { description = "Apply Kernel Variables";
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        before = [ "sysinit.target" "shutdown.target" ];
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        wantedBy = [ "sysinit.target" "multi-user.target" ];
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        restartTriggers = [ config.environment.etc."sysctl.d/nixos.conf".source ];
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        unitConfig.DefaultDependencies = false; # needed to prevent a cycle
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        serviceConfig = {
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          Type = "oneshot";
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          RemainAfterExit = true;
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          ExecStart = "${config.systemd.package}/lib/systemd/systemd-sysctl";
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        };
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      };
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    # Enable hardlink and symlink restrictions.  See
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    # https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=800179c9b8a1e796e441674776d11cd4c05d61d7
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    # for details.
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    boot.kernel.sysctl."fs.protected_hardlinks" = true;
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    boot.kernel.sysctl."fs.protected_symlinks" = true;
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    # Hide kernel pointers (e.g. in /proc/modules) for unprivileged
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    # users as these make it easier to exploit kernel vulnerabilities.
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    boot.kernel.sysctl."kernel.kptr_restrict" = 1;
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  };
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}
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