dotfiles/nixos/modules/influx-provisioning.nix

{
  config,
  pkgs,
  lib,
  ...
}: let
  cfg = config.services.influxdb2.provision;

  inherit
    (lib)
    mkEnableOption
    mkOption
    types
    mdDoc
    flip
    mapAttrsToList
    getExe
    mkIf
    ;

  taskOptions = {...}: {
    options = {
      cron = mkOption {
        type = with types; nullOr str;
        default = null;
        description =
          mdDoc ''
          '';
      };

      every = mkOption {
        type = with types; nullOr str;
        default = null;
        description =
          mdDoc ''
          '';
      };

      fluxFile = mkOption {
        type = types.path;
        description =
          mdDoc ''
          '';
      };

      offset = mkOption {
        type = types.str;
        default = "0m";
        description =
          mdDoc ''
          '';
      };
    };
  };

  tasksFile =
    (pkgs.formats.json {}).generate "tasks.json"
    (flip mapAttrsToList cfg.tasks (
      name: value: {
        inherit name;
        flux_file = value.fluxFile;
        inherit
          (value)
          every
          cron
          offset
          ;
      }
    ));
in {
  options = {
    services.influxdb2.provision-magic = {
      enable = mkEnableOption "Enable InfluxDB2 provisioning";

      itpPackage = mkOption {
        type = types.package;
        default = pkgs.itp;
        description =
          mdDoc ''
          '';
      };

      stateFile = mkOption {
        type = types.str;
        description =
          mdDoc ''
          '';
      };

      organization = mkOption {
        type = types.str;
        description =
          mdDoc ''
          '';
      };

      tasks = mkOption {
        type = with types; attrsOf (submodule taskOptions);
        default = {};
        description =
          mdDoc ''
          '';
      };
    };
  };

  config = mkIf cfg.enable {
    systemd.services.influxdb2-provision = {
      after = ["influxdb2.service"];
      wants = ["influxdb2.service"];
      wantedBy = ["multi-user.target"];

      restartIfChanged = true;

      script = ''
        ${getExe cfg.itpPackage} -s ${cfg.stateFile} -f ${tasksFile} -o ${cfg.organization}
      '';

      serviceConfig = {
        Type = "oneshot";
        Restart = "on-failure";
        RestartSec = 3;
      };
    };

    assertions =
      flip mapAttrsToList cfg.tasks
      (n: v: {
        assertion = (v.cron != null && v.every == null) || (v.cron == null && v.every != null);
        message = "Exactly one of `services.influxdb2.provision.tasks.${n}.{cron, every}` must be non `null`";
      });
  };
}