forked from extern/nixos-installer
54 lines
2.9 KiB
Markdown
54 lines
2.9 KiB
Markdown
/*
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# Additions to `fileSystems`
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Currently, this just adds `preMountCommands`.
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## Implementation
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```nix
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#*/# end of MarkDown, beginning of NixOS module:
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dirname: inputs: moduleArgs@{ config, pkgs, lib, utils, ... }: let lib = inputs.self.lib.__internal__; in let
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inherit (inputs.config.rename) preMountCommands;
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in {
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options = {
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fileSystems = lib.mkOption { type = lib.types.attrsOf (lib.types.submodule [ { options = {
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${preMountCommands} = lib.mkOption { description = ''
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Commands to be run as root every time before mounting this filesystem **via systemd**, but after all its dependents were mounted.
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This does not order itself before or after `systemd-fsck@''${utils.escapeSystemdPath device}.service`.
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This is not implemented for mounts in the initrd (those that are `neededForBoot`) yet.
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Note that if a symlink exists at a mount point when systemd's fstab-generator runs, it will read/resolve the symlink and use the link's target as the mount point, resulting in mismatching unit names for that mount, effectively disabling its `.${preMountCommands}`.
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This does not (apparently and unfortunately) run when mounting via the `mount` command (and probably not with the `mount` system call either).
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''; type = lib.types.lines; default = ""; };
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#Also, trying to create the "device" of a "nofail" mount will not work with `mount`, as it will not even attempt to mount anything (and thus not run the `.${preMountCommands}`) if the "device" is missing.
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}; } ]);
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}; };
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config = let
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in ({
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assertions = lib.mapAttrsToList (name: fs: {
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assertion = (fs.${preMountCommands} == "") || (!utils.fsNeededForBoot fs);
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message = ''The filesystem "${name}" has `.${preMountCommands}` but is also (possibly implicitly) `.neededForBoot`. This is not currently supported.'';
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}) config.fileSystems;
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# The implementation is derived from the "mkfs-${device'}" service in nixpkgs.
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systemd.services = lib.fun.mapMergeUnique (_: args@{ mountPoint, device, depends, ... }: if (args.${preMountCommands} != "") then let
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isDevice = lib.fun.startsWith "/dev/" device;
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mountPoint' = utils.escapeSystemdPath mountPoint;
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device' = utils.escapeSystemdPath device;
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in { "pre-mount-${mountPoint'}" = {
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description = "Prepare mounting ${device} at ${mountPoint}";
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wantedBy = [ "${mountPoint'}.mount" ]; before = [ "${mountPoint'}.mount" ];
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requires = lib.optional isDevice "${device'}.device"; after = lib.optional isDevice "${device'}.device";
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unitConfig.RequiresMountsFor = depends ++ [ (builtins.dirOf device) (builtins.dirOf mountPoint) ];
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unitConfig.DefaultDependencies = false;
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serviceConfig.Type = "oneshot"; script = args.${preMountCommands};
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}; } else { }) config.fileSystems;
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});
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}
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