{ config, ... }:

let
  prometheus_user = config.systemd.services.prometheus.serviceConfig.User;

  fullDataDirPath = "/var/lib/${config.services.prometheus.stateDir}";

  filesetPath = config.mine.zfsMounts."rpool/safe/svcs/prometheus";
in {
  services.prometheus = {
    enable = true;
    globalConfig.scrape_interval = "10s";
    globalConfig.scrape_timeout = "10s";
    listenAddress = "localhost";

    # default is 15 days, we just set it to 14 to be explicit
    retentionTime = "14d";
  };

  fileSystems."${filesetPath}".neededForBoot = true;
  environment.persistence."${filesetPath}".directories = [
    fullDataDirPath
  ];

  systemd.tmpfiles.rules = [
    "Z ${fullDataDirPath} 0770 ${prometheus_user} ${prometheus_user} -"
  ];
}