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

<?php

$config = array();

$config['db_dsnw'] = 'pgsql://{{getenv "DB_USER"}}:{{getenv "DB_PASSWORD"}}@{{getenv "DB_HOST"}}/{{getenv "DB_NAME"}}';
$config['log_driver'] = 'stdout';

$config['skin'] = 'elastic';

$config['default_host'] = '{{getenv "IMAP_HOST" "tls://%n"}}';
$config['imap_conn_options'] = array(
  'ssl'         => array(
      'verify_peer'      => true,
      'verify_peer_name' => true,
  ),
);

$config['smtp_server'] = '{{getenv "SMTP_HOST" "tls://%n"}}';
$config['smtp_port'] = {{getenv "SMTP_PORT" "587"}};
$config['smtp_user'] = '%u';
$config['smtp_pass'] = '%p';
/*$config['smtp_conn_options'] = array(
  'ssl'         => array(
      'verify_peer'      => true,
      'verify_peer_name' => true,
  ),
);*/

$config['use_https'] = true;
$config['des_key'] = '{{getenv "SECRET_KEY"}}';
$config['cipher_method'] = '{{getenv "CIPHER_METHOD" "AES-256-CBC"}}';

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

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

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