depot/modules/consul-service-registry/default.nix

70 lines
1.9 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.consul;
consul = "${config.services.consul.package}/bin/consul";
consulServiceDefinition = types.submodule ({ name, ... }: {
options = {
unit = mkOption {
description = "Which systemd service to attach to.";
default = name;
type = types.str;
};
mode = mkOption {
description = "How to attach command executions to the service.";
type = types.enum [ "direct" "external" ];
default = "direct";
};
definition = mkOption {
description = "Consul service definition.";
type = types.attrs;
};
};
});
attachToService = name: conf: let
serviceJson = pkgs.writeText "consul-service-${name}.json" (builtins.toJSON conf.definition);
in {
name = {
direct = conf.unit;
external = "register-consul-svc-${conf.unit}";
}.${conf.mode};
value = {
direct = {
serviceConfig = {
ExecStartPost = "${consul} services register ${serviceJson}";
ExecStopPost = "${consul} services deregister ${serviceJson}";
};
};
external = {
after = [ "${conf.unit}.service" ];
wantedBy = [ "${conf.unit}.service" ];
unitConfig.BindsTo = "${conf.unit}.service";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart = "${consul} services register ${serviceJson}";
ExecStop = "${consul} services deregister ${serviceJson}";
};
};
}.${conf.mode};
};
in
{
options.consul = {
services = mkOption {
type = with types; attrsOf consulServiceDefinition;
default = {};
};
};
config = lib.mkIf (cfg.services != {}) {
systemd.services = mapAttrs' attachToService cfg.services;
warnings = optional (!config.services.consul.enable) "Consul service registrations found, but Consul agent is not enabled on this machine.";
};
}