{ lib }:
rec {
  mkFqdn = _: cfg: cfg.networking.fqdn;

  probesWithTag =
    {
      name,
      value ? null,
    }:
    probesConfig:
    lib.filterAttrs (
      k: v: lib.any (tag: tag.name == name && (value == null || tag.value == value)) v.tags
    ) probesConfig.monitors;

  probesWithType = type: probesConfig: lib.filterAttrs (_: v: v.type == type) probesConfig.monitors;

  fromHive =
    {
      builder,
      nodes,
      excludes ? [ ],
    }:
    lib.mkMerge (
      builtins.map (node: builder node nodes.${node}) (
        lib.subtractLists excludes (builtins.attrNames nodes)
      )
    );

  pingProbesFromHive =
    {
      mkHost,
      nodes,
      prefix ? "Ping ",
      excludes ? [ ],
      tags ? [ ],
    }:
    fromHive {
      builder = (
        node: module: {
          monitors = {
            ${prefix + node} = {
              type = "ping";
              inherit tags;
              hostname = mkHost node module.config;
            };
          };
        }
      );
      inherit nodes excludes;
    };

  httpProbesFromConfig =
    {
      config,
      excludes ? [ ],
      prefix ? "",
      type ? "keyword",
      tags ? [ ],
    }:
    let
      filter = k: v: !builtins.elem k excludes && v.globalRedirect == null;
    in
    {
      monitors = lib.mapAttrs' (
        vhostName: vhost:
        let
          hasSSL = vhost.onlySSL || vhost.enableSSL || vhost.addSSL || vhost.forceSSL;
          serverName = if vhost.serverName != null then vhost.serverName else vhostName;
        in
        {
          name = prefix + serverName;
          value = {
            inherit type;
            inherit tags;
            url = "http${lib.optionalString hasSSL "s"}://${serverName}";
            method = "get";
          };
        }
      ) (lib.filterAttrs filter config.services.nginx.virtualHosts);
    };
}