nixos-config/modules/system/services/gatus.nix

{
  config,
  self,
  lib,
  ...
}:
let
  cfg = config.custom.services.gatus;

  tailscaleDomain = config.custom.services.tailscale.domain;
in
{
  options.custom.services.gatus = {
    enable = lib.mkEnableOption "";
    domain = lib.mkOption {
      type = lib.types.nonEmptyStr;
      default = "";
    };
    port = lib.mkOption {
      type = lib.types.port;
      default = 8080;
    };
    endpoints = lib.mkOption {
      type = lib.types.attrsOf (
        lib.types.submodule (
          { name, ... }:
          {
            options = {
              name = lib.mkOption {
                type = lib.types.nonEmptyStr;
                default = name;
              };
              group = lib.mkOption {
                type = lib.types.str;
                default = "";
              };
              url = lib.mkOption {
                type = lib.types.nonEmptyStr;
                default = "";
              };
              extraConditions = lib.mkOption {
                type = lib.types.listOf lib.types.nonEmptyStr;
                default = [ ];
              };
            };
          }
        )
      );
      default = { };
    };
  };

  config = lib.mkIf cfg.enable {
    meta.ports.list = [ cfg.port ];

    services.gatus = {
      enable = true;

      settings = {
        web.port = cfg.port;

        storage = {
          type = "sqlite";
          path = "/var/lib/gatus/data.db";
        };

        connectivity.checker.target = "1.1.1.1:53";

        alerting = {
          ntfy = {
            topic = "uptime";
            url = "https://alerts.${tailscaleDomain}";
            click = "https://${cfg.domain}";
            default-alert = {
              enable = true;
              failure-threshold = 4;
              success-threshold = 2;
              send-on-resolved = true;
            };
          };
        };

        maintenance = {
          start = "03:00";
          duration = "1h";
          timezone = "Europe/Berlin";
        };

        endpoints =
          self.nixosConfigurations
          |> lib.mapAttrsToList (_: value: value.config.custom.services.gatus.endpoints)
          |> lib.map (entry: lib.mapAttrsToList (_: value: value) entry)
          |> lib.flatten
          |> lib.map (value: {
            inherit (value) name group url;
            interval = "30s";
            alerts = [ { type = "ntfy"; } ];
            ssh = lib.mkIf (lib.hasPrefix "ssh" value.url) {
              username = "";
              password = "";
            };
            conditions = lib.flatten [
              value.extraConditions
              (lib.optional (lib.hasPrefix "http" value.url) "[STATUS] == 200")
              (lib.optional (lib.hasPrefix "tcp" value.url) "[CONNECTED] == true")
              (lib.optional (lib.hasPrefix "ssh" value.url) "[CONNECTED] == true")
            ];
          });
      };
    };
  };
}