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

74 lines
2.2 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.consul;
consul = "${config.services.consul.package}/bin/consul";
consulServiceDefinition = types.submodule ({ name, ... }: {
options = {
unit = mkOption {
description = "Which systemd service to attach to.";
default = name;
type = types.str;
};
mode = mkOption {
description = "How to attach command executions to the service.";
type = types.enum [ "direct" "external" ];
default = "direct";
};
definition = mkOption {
description = "Consul service definition.";
type = types.attrs;
};
};
});
attachToService = unit: servicesRaw: let
services = map (getAttr "definition") servicesRaw;
servicesJson = pkgs.writeText "consul-services-${unit}.json" (builtins.toJSON { inherit services; });
mode = if any (x: x.mode == "external") servicesRaw then "external" else "direct";
in {
name = {
direct = unit;
external = "register-consul-svc-${unit}";
}.${mode};
value = {
direct = {
serviceConfig = {
ExecStartPost = "${consul} services register ${servicesJson}";
ExecStopPost = "${consul} services deregister ${servicesJson}";
};
};
external = {
after = [ "${unit}.service" ];
wantedBy = [ "${unit}.service" ];
unitConfig.BindsTo = "${unit}.service";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStart = "${consul} services register ${servicesJson}";
ExecStop = "${consul} services deregister ${servicesJson}";
Restart = "on-failure";
RestartSec = "1s";
};
};
}.${mode};
};
in
{
options.consul = {
services = mkOption {
type = with types; attrsOf consulServiceDefinition;
default = {};
};
};
config = lib.mkIf (cfg.services != {}) {
systemd.services = mapAttrs' attachToService (groupBy (getAttr "unit") (attrValues cfg.services));
warnings = optional (!config.services.consul.enable) "Consul service registrations found, but Consul agent is not enabled on this machine.";
};
}