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29027fd1e1
Using pkgs.lib on the spine of module evaluation is problematic because the pkgs argument depends on the result of module evaluation. To prevent an infinite recursion, pkgs and some of the modules are evaluated twice, which is inefficient. Using ‘with lib’ prevents this problem.
122 lines
3.4 KiB
Nix
122 lines
3.4 KiB
Nix
{ config, lib, pkgs, utils, ... }:
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with lib;
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with utils;
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{
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###### interface
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options = {
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swapDevices = mkOption {
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default = [];
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example = [
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{ device = "/dev/hda7"; }
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{ device = "/var/swapfile"; }
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{ label = "bigswap"; }
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];
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description = ''
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The swap devices and swap files. These must have been
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initialised using <command>mkswap</command>. Each element
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should be an attribute set specifying either the path of the
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swap device or file (<literal>device</literal>) or the label
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of the swap device (<literal>label</literal>, see
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<command>mkswap -L</command>). Using a label is
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recommended.
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'';
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type = types.listOf types.optionSet;
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options = {config, options, ...}: {
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options = {
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device = mkOption {
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example = "/dev/sda3";
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type = types.str;
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description = "Path of the device.";
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};
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label = mkOption {
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example = "swap";
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type = types.str;
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description = ''
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Label of the device. Can be used instead of <varname>device</varname>.
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'';
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};
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size = mkOption {
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default = null;
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example = 2048;
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type = types.nullOr types.int;
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description = ''
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If this option is set, ‘device’ is interpreted as the
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path of a swapfile that will be created automatically
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with the indicated size (in megabytes) if it doesn't
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exist.
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'';
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};
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priority = mkOption {
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default = null;
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example = 2048;
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type = types.nullOr types.int;
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description = ''
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Specify the priority of the swap device. Priority is a value between 0 and 32767.
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Higher numbers indicate higher priority.
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null lets the kernel choose a priority, which will show up as a negative value.
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'';
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};
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};
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config = {
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device = mkIf options.label.isDefined
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"/dev/disk/by-label/${config.label}";
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};
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};
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};
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};
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config = mkIf ((length config.swapDevices) != 0) {
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system.requiredKernelConfig = with config.lib.kernelConfig; [
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(isYes "SWAP")
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];
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# Create missing swapfiles.
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# FIXME: support changing the size of existing swapfiles.
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systemd.services =
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let
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createSwapDevice = sw:
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assert sw.device != "";
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let device' = escapeSystemdPath sw.device; in
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nameValuePair "mkswap-${escapeSystemdPath sw.device}"
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{ description = "Initialisation of Swapfile ${sw.device}";
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wantedBy = [ "${device'}.swap" ];
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before = [ "${device'}.swap" ];
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path = [ pkgs.utillinux ];
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script =
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''
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if [ ! -e "${sw.device}" ]; then
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fallocate -l ${toString sw.size}M "${sw.device}" ||
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dd if=/dev/zero of="${sw.device}" bs=1M count=${toString sw.size}
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mkswap ${sw.device}
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fi
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'';
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unitConfig.RequiresMountsFor = [ "${dirOf sw.device}" ];
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unitConfig.DefaultDependencies = false; # needed to prevent a cycle
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serviceConfig.Type = "oneshot";
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};
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in listToAttrs (map createSwapDevice (filter (sw: sw.size != null) config.swapDevices));
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};
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}
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