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dotfiles/flake/guest.nix

269 lines
10 KiB
Nix

{
inputs,
lib,
specialArgs,
repositoryModules,
registryAssembly,
util,
}:
{
mkGuest =
{
name,
interior ? { },
}:
{ config, lib, ... }:
let
cfg = config.guests.${name};
directoryMounts = lib.filterAttrs (_: mount: mount.directory != null) cfg.mounts;
directoryScript = lib.concatStringsSep "\n" (
lib.mapAttrsToList (
_: mount:
''
${config.system.path}/bin/install -d \
${lib.optionalString (mount.owner != null) "-o ${lib.escapeShellArg (toString mount.owner)}"} \
${lib.optionalString (mount.group != null) "-g ${lib.escapeShellArg mount.group}"} \
${lib.optionalString (mount.mode != null) "-m ${lib.escapeShellArg mount.mode}"} \
${lib.escapeShellArg mount.directory}
''
) directoryMounts
);
in
{
options.guests.${name} = {
enable = lib.mkEnableOption "the ${name} guest, run in its own nested container";
vlan = lib.mkOption {
type = lib.types.ints.between 1 4094;
example = 10;
description = ''
The tagged VLAN this guest lives on. The guest attaches to its host's
`br-vlan<id>` bridge for that VLAN. The id must be one of the host's
`modules.network.vlans.ids`.
'';
};
mac = lib.mkOption {
type = lib.types.str;
default = util.deriveMac "${config.networking.hostName}.${name}";
defaultText = lib.literalMD "a stable address derived from the host name and guest option path";
example = "bc:24:11:00:00:01";
description = ''
The guest's MAC address on its VLAN, pinned inside the guest by its
own networkd. Set it to reuse an existing address so a router's DHCP
reservation keeps working. Left unset, a stable address is derived
from the host name and guest option path in the locally-administered range.
'';
};
address = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "10.23.20.126";
description = ''
Expected IP address assigned outside NixOS for this guest.
Left null, this guest contributes no address to the address registry.
'';
};
reverseProxy = {
enable = lib.mkEnableOption "a reverse-proxy route for this guest";
route = lib.mkOption {
type = registryAssembly.definitions.route.type;
description = "Route registry entry published for this guest.";
};
};
mounts = lib.mkOption {
type = lib.types.attrsOf (
lib.types.submodule {
options = {
directory = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "/srv/media";
description = "Host directory bind-mounted into the guest.";
};
file = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "/run/secrets/service-password";
description = "Host file bind-mounted into the guest.";
};
readOnly = lib.mkOption {
type = lib.types.bool;
default = false;
description = "Mount the host path read-only inside the guest.";
};
owner = lib.mkOption {
type = lib.types.nullOr (
lib.types.oneOf [
lib.types.str
lib.types.ints.positive
]
);
default = null;
description = "Owner assigned to the host directory before the guest starts.";
};
group = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
description = "Group assigned to the host directory before the guest starts.";
};
mode = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "0770";
description = "Mode assigned to the host directory before the guest starts.";
};
};
}
);
default = { };
example = lib.literalExpression ''
{
"/data/media" = { directory = "/srv/media"; };
"/data/config" = { directory = "/srv/config/jellyfin"; };
}
'';
description = ''
Host paths bind-mounted into the guest, keyed by the path they appear
at inside the guest, so a guest sees exactly the data it should at any
granularity — a single folder, a whole pool, or a decrypted secret.
Mounts are read-write unless `readOnly` is set.
'';
};
limits = {
memory = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "2G";
description = ''
Cap on the guest's memory, applied to its unit as `MemoryMax`.
Accepts systemd size suffixes such as `512M` or `2G`. Left null,
the guest's memory is uncapped.
'';
};
cpu = lib.mkOption {
type = lib.types.nullOr lib.types.str;
default = null;
example = "150%";
description = ''
Cap on the guest's CPU, applied to its unit as `CPUQuota`, where
`100%` is one full core. Left null, the guest's CPU is uncapped.
'';
};
tasksMax = lib.mkOption {
type = lib.types.nullOr lib.types.ints.positive;
default = null;
example = 512;
description = ''
Cap on the number of processes and threads the guest may spawn,
applied to its unit as `TasksMax`. Left null, the task count is
uncapped.
'';
};
};
};
config = lib.mkIf cfg.enable {
assertions =
let
hasDirectorySettings = mount: mount.owner != null || mount.group != null || mount.mode != null;
hasCompleteDirectorySettings = mount: mount.owner != null && mount.group != null && mount.mode != null;
hasOneSource = mount: (mount.directory != null) != (mount.file != null);
mountsWithInvalidSource = lib.attrNames (lib.filterAttrs (_: mount: !hasOneSource mount) cfg.mounts);
fileMountsWithHostSettings = lib.attrNames (
lib.filterAttrs (_: mount: mount.file != null && hasDirectorySettings mount) cfg.mounts
);
directoryMountsWithPartialHostSettings = lib.attrNames (
lib.filterAttrs (_: mount: mount.directory != null && hasDirectorySettings mount && !hasCompleteDirectorySettings mount) cfg.mounts
);
in
[
{
assertion = mountsWithInvalidSource == [ ];
message = ''
guests.${name} mounts ${lib.concatStringsSep ", " mountsWithInvalidSource} must set exactly one of `directory` or `file`.
'';
}
{
assertion = fileMountsWithHostSettings == [ ];
message = ''
guests.${name} file mounts ${lib.concatStringsSep ", " fileMountsWithHostSettings} must not set `owner`, `group`, or `mode`.
'';
}
{
assertion = directoryMountsWithPartialHostSettings == [ ];
message = ''
guests.${name} directory mounts ${lib.concatStringsSep ", " directoryMountsWithPartialHostSettings} must set `owner`, `group`, and `mode` together.
'';
}
{
assertion = lib.elem cfg.vlan config.modules.network.vlans.ids;
message = ''
guests.${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.
'';
}
];
registry.address.${config.networking.hostName}.${name} =
lib.mkIf (cfg.address != null) cfg.address;
registry.route.${config.networking.hostName}.${name} =
lib.mkIf cfg.reverseProxy.enable cfg.reverseProxy.route;
systemd.services."container@${name}" =
let
bridgeDevice = "sys-subsystem-net-devices-${lib.replaceStrings [ "-" ] [ "\\x2d" ] (util.bridgeName cfg.vlan)}.device";
in
{
after = [ bridgeDevice ];
wants = [ bridgeDevice ];
serviceConfig = lib.filterAttrs (_: v: v != null) {
MemoryMax = cfg.limits.memory;
CPUQuota = cfg.limits.cpu;
TasksMax = cfg.limits.tasksMax;
};
preStart = lib.mkIf (directoryMounts != { }) directoryScript;
};
containers.${name} = {
autoStart = true;
privateNetwork = lib.mkDefault true;
hostBridge = util.bridgeName cfg.vlan;
privateUsers = lib.mkDefault "no";
bindMounts = lib.mapAttrs (_: mount: {
hostPath = if mount.directory != null then mount.directory else mount.file;
isReadOnly = mount.readOnly;
}) cfg.mounts;
inherit specialArgs;
config = {
imports = [
inputs.sops-nix.nixosModules.sops
inputs.stylix.nixosModules.stylix
repositoryModules
registryAssembly.module
interior
{
modules.guest.enable = true;
networking.useNetworkd = true;
networking.useHostResolvConf = false;
systemd.network.networks."20-eth0" = {
matchConfig.Name = "eth0";
linkConfig.MACAddress = cfg.mac;
networkConfig.DHCP = "yes";
};
}
];
};
};
};
};
}