refactor(flake): move assembly code out of lib
This commit is contained in:
370
flake/guests.nix
Normal file
370
flake/guests.nix
Normal file
@@ -0,0 +1,370 @@
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{
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inputs,
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lib,
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self,
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specialArgs,
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bridgeName,
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moduleFiles,
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registryAssembly,
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}:
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let
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inherit (lib) escapeShellArg mapAttrsToList;
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deriveMac =
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name:
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let
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hash = builtins.hashString "sha256" name;
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octet = i: builtins.substring (i * 2) 2 hash;
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in
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lib.concatStringsSep ":" ([ "02" ] ++ map octet [ 0 1 2 3 4 ]);
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guest =
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{
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name,
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interior ? { },
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}:
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{ config, lib, ... }:
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let
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optionPath = [ "guests" ] ++ lib.splitString "." name;
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cfg = lib.getAttrFromPath optionPath config;
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machineName = lib.replaceStrings [ "." ] [ "-" ] name;
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networked = cfg.vlan != null;
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userMounts = lib.mapAttrs (_guestPath: m: {
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inherit (m) hostPath;
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isReadOnly = m.readOnly;
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}) cfg.mounts;
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secretMounts = lib.listToAttrs (
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map (
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name:
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let
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path = config.sops.secrets.${name}.path;
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in
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lib.nameValuePair path {
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hostPath = path;
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isReadOnly = true;
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}
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) cfg.secrets
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);
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mountCollisions = lib.attrNames (builtins.intersectAttrs userMounts secretMounts);
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limitConfig = lib.filterAttrs (_: v: v != null) {
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MemoryMax = cfg.limits.memory;
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CPUQuota = cfg.limits.cpu;
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TasksMax = cfg.limits.tasksMax;
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};
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createdMounts = lib.filterAttrs (_guestPath: m: m.create != null) cfg.mounts;
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mountCreateScript = lib.concatStringsSep "\n" (
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mapAttrsToList (
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_guestPath: m:
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let
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create = m.create;
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in
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''
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${config.system.path}/bin/install -d -o ${escapeShellArg (toString create.owner)} -g ${escapeShellArg create.group} -m ${escapeShellArg create.mode} ${escapeShellArg m.hostPath}
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''
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) createdMounts
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);
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guestNet =
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{ lib, ... }:
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{
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config = lib.mkIf networked {
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networking.useNetworkd = true;
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networking.useHostResolvConf = false;
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systemd.network.networks."20-eth0" = {
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matchConfig.Name = "eth0";
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linkConfig.MACAddress = cfg.mac;
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networkConfig.DHCP = "yes";
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};
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};
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};
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in
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{
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options = lib.setAttrByPath optionPath {
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enable = lib.mkEnableOption "the ${name} guest, run in its own nested container";
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backend = lib.mkOption {
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type = lib.types.enum [
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"container"
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"microvm"
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];
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default = "container";
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description = ''
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How the guest is realized. `container` runs the guest as a
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systemd-nspawn nested container. `microvm` is reserved for a future
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hard-isolation backend and is not built yet.
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'';
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};
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vlan = lib.mkOption {
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type = lib.types.nullOr (lib.types.ints.between 1 4094);
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default = null;
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example = 10;
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description = ''
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The tagged VLAN this guest lives on. The guest attaches to its host's
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`br-vlan<id>` bridge for that VLAN. Left null, the guest keeps a
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private network with no bridge attachment. The id must be one of the
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host's `modules.network.vlans.ids`.
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'';
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};
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mac = lib.mkOption {
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type = lib.types.str;
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default = deriveMac name;
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defaultText = lib.literalMD "a stable address derived from the guest's namespace path";
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example = "bc:24:11:00:00:01";
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description = ''
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The guest's MAC address on its VLAN, pinned inside the guest by its
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own networkd. Set it to reuse an existing address so a router's DHCP
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reservation keeps working. Left unset, a stable address is derived
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from the guest's namespace path in the locally-administered range.
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'';
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};
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address = lib.mkOption {
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type = lib.types.nullOr lib.types.str;
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default = null;
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example = "10.23.20.126";
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description = ''
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Expected IP address assigned outside NixOS for this guest.
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Left null, this guest contributes no address to the address registry.
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'';
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};
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reverseProxy = {
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enable = lib.mkEnableOption "a reverse-proxy route for this guest";
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route = lib.mkOption {
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type = registryAssembly.definitions.route.type;
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description = "Route registry entry published for this guest.";
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};
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};
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mounts = lib.mkOption {
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type = lib.types.attrsOf (
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lib.types.submodule {
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options = {
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hostPath = lib.mkOption {
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type = lib.types.str;
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example = "/srv/media";
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description = "The path on the host bind-mounted into the guest.";
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};
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readOnly = lib.mkOption {
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type = lib.types.bool;
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default = false;
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description = ''
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Mount the path read-only. Read-write by default, since a
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service must write to the pool data it owns.
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'';
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};
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create = lib.mkOption {
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type = lib.types.nullOr (lib.types.submodule {
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options = {
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type = lib.mkOption {
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type = lib.types.enum [ "directory" ];
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default = "directory";
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description = "Host path type to create before the guest starts.";
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};
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owner = lib.mkOption {
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type = lib.types.oneOf [
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lib.types.str
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lib.types.ints.positive
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];
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description = "Owner assigned to the created host path.";
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};
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group = lib.mkOption {
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type = lib.types.str;
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description = "Group assigned to the created host path.";
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};
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mode = lib.mkOption {
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type = lib.types.str;
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example = "0770";
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description = "Mode assigned to the created host path.";
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};
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};
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});
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default = null;
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description = ''
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Opt-in host path creation before the guest starts. Existing
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paths are left enabled unless this is set, so served storage
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roots can still be required to exist explicitly.
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'';
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};
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};
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}
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);
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default = { };
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example = lib.literalExpression ''
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{
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"/data/media" = { hostPath = "/srv/media"; };
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"/data/config" = {
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hostPath = "/srv/config/jellyfin";
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readOnly = true;
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};
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}
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'';
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description = ''
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Host paths bind-mounted into the guest, keyed by the path they appear
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at inside the guest, so a guest sees exactly the data it should at any
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granularity — a single folder or a whole pool. Each mount is
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read-write unless `readOnly` is set.
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'';
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};
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secrets = lib.mkOption {
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type = lib.types.listOf lib.types.str;
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default = [ ];
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example = [ "jellyfin-api-key" ];
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description = ''
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Names of the secrets this guest needs. The host is the sole
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decryptor: it decrypts each named secret from its own sops files and
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bind-mounts the plaintext file into the guest read-only at
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`/run/secrets/<name>`, the same path it would occupy on a host, so a
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service reads its credentials at a predictable location. The guest
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names the files it wants and receives exactly those. It holds no age
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key and decrypts nothing itself. Ownership carries across unchanged,
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since the container maps ids one to one, so a secret owned by a uid on
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the host is owned by that same uid inside the guest.
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'';
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};
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limits = {
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memory = lib.mkOption {
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type = lib.types.nullOr lib.types.str;
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default = null;
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example = "2G";
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description = ''
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Cap on the guest's memory, applied to its unit as `MemoryMax`.
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Accepts systemd size suffixes such as `512M` or `2G`. Left null,
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the guest's memory is uncapped.
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'';
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};
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cpu = lib.mkOption {
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type = lib.types.nullOr lib.types.str;
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default = null;
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example = "150%";
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description = ''
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Cap on the guest's CPU, applied to its unit as `CPUQuota`, where
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`100%` is one full core. Left null, the guest's CPU is uncapped.
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'';
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};
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tasksMax = lib.mkOption {
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type = lib.types.nullOr lib.types.ints.positive;
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default = null;
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example = 512;
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description = ''
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Cap on the number of processes and threads the guest may spawn,
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applied to its unit as `TasksMax`. Left null, the task count is
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uncapped.
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'';
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};
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};
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nesting = lib.mkOption {
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type = lib.types.bool;
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default = false;
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description = ''
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Grant the guest's interior the prerequisites to run Podman or other
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OCI containers of its own. Off by default, so a guest cannot nest
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containers. On, the guest's container gains the network-administration
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capability its container runtime uses to build bridges and firewall
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rules, along with the tun and fuse device nodes such a runtime reaches
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for, so the interior's `virtualisation.oci-containers` works with
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Podman as its default runtime.
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'';
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};
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autoStart = lib.mkOption {
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type = lib.types.bool;
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default = true;
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description = ''
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Start the guest at boot. On by default. Disabled, the guest stays
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defined and can be started on demand, but does not come up at boot.
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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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sops.secrets = lib.genAttrs cfg.secrets (_: { });
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registry.address.${config.networking.hostName}.${machineName} = lib.mkIf (cfg.address != null) cfg.address;
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registry.route.${config.networking.hostName}.${machineName} = lib.mkIf cfg.reverseProxy.enable cfg.reverseProxy.route;
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assertions = [
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{
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assertion = mountCollisions == [ ];
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message = ''
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guests.${name} maps a mount at ${lib.concatStringsSep ", " mountCollisions}, colliding with a secret bind-mounted at the same path. Rename the mount or the secret so each in-guest path is used once.
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'';
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}
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{
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assertion = cfg.backend == "container";
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message = ''
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guests.${name}.backend = "${cfg.backend}" is not implemented. Only the "container" backend is built; "microvm" is reserved for future work.
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'';
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}
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{
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assertion = !networked || lib.elem cfg.vlan config.modules.network.vlans.ids;
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message = ''
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guests.${name}.vlan = ${toString cfg.vlan} is not among its host's modules.network.vlans.ids (${lib.concatMapStringsSep ", " toString config.modules.network.vlans.ids}). Declare the VLAN on the host or correct the guest's placement.
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'';
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}
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];
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systemd.services."container@${machineName}" = lib.mkIf (cfg.backend == "container") (
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lib.mkMerge [
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{
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serviceConfig = limitConfig;
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preStart = lib.mkIf (createdMounts != { }) mountCreateScript;
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}
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(lib.mkIf networked (
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let
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bridgeDevice = "sys-subsystem-net-devices-${lib.replaceStrings [ "-" ] [ "\\x2d" ] (bridgeName cfg.vlan)}.device";
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in
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{
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after = [ bridgeDevice ];
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wants = [ bridgeDevice ];
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}
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))
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]
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);
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containers.${machineName} = lib.mkIf (cfg.backend == "container") {
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autoStart = cfg.autoStart;
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privateNetwork = lib.mkDefault true;
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hostBridge = lib.mkIf networked (bridgeName cfg.vlan);
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privateUsers = lib.mkDefault "no";
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additionalCapabilities = lib.optionals cfg.nesting [ "CAP_NET_ADMIN" ];
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allowedDevices = lib.optionals cfg.nesting [
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{
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node = "/dev/net/tun";
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modifier = "rwm";
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}
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{
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node = "/dev/fuse";
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modifier = "rwm";
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}
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];
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bindMounts = userMounts // secretMounts;
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inherit specialArgs;
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config = {
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imports =
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moduleFiles
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++ [
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registryAssembly.module
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inputs.sops-nix.nixosModules.sops
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inputs.stylix.nixosModules.stylix
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{
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modules.guest.enable = true;
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}
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guestNet
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interior
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];
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};
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};
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};
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};
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in
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{
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inherit deriveMac guest;
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}
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Reference in New Issue
Block a user