alexion
7edc1ce94b
Add `modules.zfs`, the host-level pool import: a host declares its ZFS host id and the pools to import with their dataset mountpoints, and the module imports those pools as durable state rather than recreating them, so a service's data survives any rebuild or reimage. Add a shared `storage` group with a fixed gid to the base config both the host base and the guest-base build on, so a host and every guest carry the same number and an identity-mapped container write lands on the pool as that group without per-service permission juggling. No host enables the module: the only host is a laptop with no pools and a kernel with no ZFS build, so the enabled build was verified by ad-hoc enablement against a ZFS-supported kernel while the committed tree stays inert.
73 lines
2.3 KiB
Nix
73 lines
2.3 KiB
Nix
{
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config,
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lib,
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...
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}:
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# The host-level ZFS pool import: durable service state a host mounts, never rebuilds.
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let
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cfg = config.modules.zfs;
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in
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{
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options.modules.zfs = {
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enable = lib.mkEnableOption "importing durable ZFS pools that hold service state";
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hostId = lib.mkOption {
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type = lib.types.strMatching "[0-9a-f]{8}";
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example = "deadbeef";
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description = ''
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This host's 8-hex-digit ZFS host id, written to `networking.hostId`. ZFS
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stamps an imported pool with the importing host's id, so a pool still
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held by another machine is refused rather than silently dual-mounted. It
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must be fixed for the machine and distinct across machines that can reach
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the same pool.
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'';
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};
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pools = lib.mkOption {
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type = lib.types.attrsOf (lib.types.attrsOf lib.types.path);
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default = { };
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example = lib.literalExpression ''
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{
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tank = {
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media = "/srv/media";
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downloads = "/srv/downloads";
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};
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}
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'';
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description = ''
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The ZFS pools to import at boot, keyed by pool name, each pool mapping a
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dataset path relative to it to that dataset's mountpoint. A pool is
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durable state imported as it stands, never created or destroyed by a
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rebuild, so a service's data survives any rebuild or reimage. A pool
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with an empty map is still imported, leaving each dataset to its own ZFS
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`mountpoint` property.
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'';
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};
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};
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config = lib.mkIf cfg.enable {
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# The ZFS stack in the kernel and boot, needed even where the root filesystem is another kind.
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boot.supportedFilesystems = [ "zfs" ];
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# ZFS refuses to import a pool without a host id to stamp its ownership onto.
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networking.hostId = cfg.hostId;
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# The declared pools are imported at boot, distinct from any pool backing the root filesystem.
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boot.zfs.extraPools = lib.attrNames cfg.pools;
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# Each declared dataset is mounted at its host path as a native ZFS filesystem.
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fileSystems = lib.mkMerge (
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lib.mapAttrsToList (
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pool: mounts:
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lib.mapAttrs' (
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dataset: mountpoint:
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lib.nameValuePair mountpoint {
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device = "${pool}/${dataset}";
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fsType = "zfs";
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}
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) mounts
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) cfg.pools
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);
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};
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}
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