roundcube/rootfs/etc/confd/templates/config.inc.php.tmpl

<?php

$config = array();

$config['db_dsnw'] = 'pgsql://{{getenv "DBUSER"}}:{{getenv "DBPASSWORD"}}@{{getenv "DBHOST"}}/{{getenv "DBNAME"}}';
$config['log_driver'] = 'syslog';
$config['syslog_facility'] = LOG_USER;

$config['default_host'] = '{{getenv "IMAPHOST"}}';
$config['imap_conn_options'] = array(
  'ssl'         => array(
      'verify_peer'      => false,
      'verify_peer_name' => false,
  ),
);

$config['smtp_server'] = '{{getenv "SMTPHOST"}}';
$config['smtp_port'] = 587;
$config['smtp_user'] = '%u';
$config['smtp_pass'] = '%p';
$config['smtp_conn_options'] = array(
  'ssl'         => array(
      'verify_peer'      => false,
      'verify_peer_name' => false,
  ),
);

$config['use_https'] = true;
$config['des_key'] = '{{getenv "KEY"}}';
$config['cipher_method'] = '{{getenv "CIPHERMETHOD"}}';

$config['mail_domain'] = '%t';
$config['username_domain'] = '%d';
$config['username_domain_forced'] = true;
$config['password_charset'] = 'UTF-8';

$config['plugins'] = array('managesieve', 'password', 'archive', 'zipdownload');

$config['spellcheck_engine'] = 'pspell';
$config['default_charset'] = 'UTF-8';