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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.nomad;
format = pkgs.formats.json { };
in
{
##### interface
options = {
services.nomad = {
enable = mkEnableOption (lib.mdDoc "Nomad, a distributed, highly available, datacenter-aware scheduler");
package = mkOption {
type = types.package;
default = pkgs.nomad;
defaultText = literalExpression "pkgs.nomad";
description = lib.mdDoc ''
The package used for the Nomad agent and CLI.
'';
};
extraPackages = mkOption {
type = types.listOf types.package;
default = [ ];
description = lib.mdDoc ''
Extra packages to add to {env}`PATH` for the Nomad agent process.
'';
example = literalExpression ''
with pkgs; [ cni-plugins ]
'';
};
dropPrivileges = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Whether the nomad agent should be run as a non-root nomad user.
'';
};
enableDocker = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Enable Docker support. Needed for Nomad's docker driver.
Note that the docker group membership is effectively equivalent
to being root, see https://github.com/moby/moby/issues/9976.
'';
};
extraSettingsPaths = mkOption {
type = types.listOf types.path;
default = [ ];
description = lib.mdDoc ''
Additional settings paths used to configure nomad. These can be files or directories.
'';
example = literalExpression ''
[ "/etc/nomad-mutable.json" "/run/keys/nomad-with-secrets.json" "/etc/nomad/config.d" ]
'';
};
extraSettingsPlugins = mkOption {
type = types.listOf (types.either types.package types.path);
default = [ ];
description = lib.mdDoc ''
Additional plugins dir used to configure nomad.
'';
example = literalExpression ''
[ "<pluginDir>" pkgs.nomad-driver-nix pkgs.nomad-driver-podman ]
'';
};
credentials = mkOption {
description = lib.mdDoc ''
Credentials envs used to configure nomad secrets.
'';
type = types.attrsOf types.str;
default = { };
example = {
logs_remote_write_password = "/run/keys/nomad_write_password";
};
};
settings = mkOption {
type = format.type;
default = { };
description = lib.mdDoc ''
Configuration for Nomad. See the [documentation](https://www.nomadproject.io/docs/configuration)
for supported values.
Notes about `data_dir`:
If `data_dir` is set to a value other than the
default value of `"/var/lib/nomad"` it is the Nomad
cluster manager's responsibility to make sure that this directory
exists and has the appropriate permissions.
Additionally, if `dropPrivileges` is
`true` then `data_dir`
*cannot* be customized. Setting
`dropPrivileges` to `true` enables
the `DynamicUser` feature of systemd which directly
manages and operates on `StateDirectory`.
'';
example = literalExpression ''
{
# A minimal config example:
server = {
enabled = true;
bootstrap_expect = 1; # for demo; no fault tolerance
};
client = {
enabled = true;
};
}
'';
};
};
};
##### implementation
config = mkIf cfg.enable {
services.nomad.settings = {
# Agrees with `StateDirectory = "nomad"` set below.
data_dir = mkDefault "/var/lib/nomad";
};
environment = {
etc."nomad.json".source = format.generate "nomad.json" cfg.settings;
systemPackages = [ cfg.package ];
};
systemd.services.nomad = {
description = "Nomad";
wantedBy = [ "multi-user.target" ];
wants = [ "network-online.target" ];
after = [ "network-online.target" ];
restartTriggers = [ config.environment.etc."nomad.json".source ];
path = cfg.extraPackages ++ (with pkgs; [
# Client mode requires at least the following:
coreutils
iproute2
iptables
]);
serviceConfig = mkMerge [
{
DynamicUser = cfg.dropPrivileges;
ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
ExecStart =
let
pluginsDir = pkgs.symlinkJoin
{
name = "nomad-plugins";
paths = cfg.extraSettingsPlugins;
};
in
"${cfg.package}/bin/nomad agent -config=/etc/nomad.json -plugin-dir=${pluginsDir}/bin" +
concatMapStrings (path: " -config=${path}") cfg.extraSettingsPaths +
concatMapStrings (key: " -config=\${CREDENTIALS_DIRECTORY}/${key}") (lib.attrNames cfg.credentials);
KillMode = "process";
KillSignal = "SIGINT";
LimitNOFILE = 65536;
LimitNPROC = "infinity";
OOMScoreAdjust = -1000;
Restart = "on-failure";
RestartSec = 2;
TasksMax = "infinity";
LoadCredential = lib.mapAttrsToList (key: value: "${key}:${value}") cfg.credentials;
}
(mkIf cfg.enableDocker {
SupplementaryGroups = "docker"; # space-separated string
})
(mkIf (cfg.settings.data_dir == "/var/lib/nomad") {
StateDirectory = "nomad";
})
];
unitConfig = {
StartLimitIntervalSec = 10;
StartLimitBurst = 3;
};
};
assertions = [
{
assertion = cfg.dropPrivileges -> cfg.settings.data_dir == "/var/lib/nomad";
message = "settings.data_dir must be equal to \"/var/lib/nomad\" if dropPrivileges is true";
}
];
# Docker support requires the Docker daemon to be running.
virtualisation.docker.enable = mkIf cfg.enableDocker true;
};
}
|