liminix/modules/hostapd/service.nix

{
  liminix,
  svc,
  hostapd,
  output-template,
  writeText,
  lib,
}:
{ interface, params }:
let
  inherit (liminix.services) longrun;
  inherit (lib) concatStringsSep mapAttrsToList unique;
  inherit (builtins)
    map
    filter
    attrValues
    length
    head
    typeOf
    ;

  # This is not a friendly interface to configuring a wireless AP: it
  # just passes everything straight through to the hostapd config.
  # When we've worked out what the sensible options are to expose,
  # we'll add them as top-level attributes and rename params to
  # extraParams

  name = "${interface.name}.hostapd";
  defaults = {
    driver = "nl80211";
    logger_syslog = "-1";
    logger_syslog_level = 1;
    ctrl_interface = "/run/${name}";
    ctrl_interface_group = 0;
  };
  attrs = defaults // params;
  literal_or_output =
    o:
    (
      {
        string = builtins.toJSON;
        int = builtins.toJSON;
        lambda = (o: "output(${builtins.toJSON (o "service")}, ${builtins.toJSON (o "path")})");
      }
      .${builtins.typeOf o}
    )
      o;

  conf = (
    writeText "hostapd.conf.in" (
      (concatStringsSep "\n" (mapAttrsToList (n: v: "${n}={{ ${literal_or_output v} }}") attrs)) + "\n"
    )
  );
  service = longrun {
    inherit name;
    dependencies = [ interface ];
    run = ''
      mkdir -p /run/${name}
      chmod 0700 /run/${name}
      ${output-template}/bin/output-template '{{' '}}' < ${conf} > /run/${name}/hostapd.conf
      exec ${hostapd}/bin/hostapd -i $(output ${interface} ifname) -P /run/${name}/hostapd.pid -S /run/${name}/hostapd.conf
    '';
  };
  watch = filter (f: typeOf f == "lambda") (attrValues attrs);
in
svc.secrets.subscriber.build {
  inherit service watch;
  action = "restart-all";
}