'ssl' => [
        /*
         * Path to local certificate file on filesystem. It must be a PEM encoded file which
         * contains your certificate and private key. It can optionally contain the
         * certificate chain of issuers. The private key also may be contained
         * in a separate file specified by local_pk.
         */
        'local_cert' => '/var/www/server.crt',
//        'local_cert' => null,

        /*
         * Path to local private key file on filesystem in case of separate files for
         * certificate (local_cert) and private key.
         */
        'local_pk' => '/var/www/server.key',
//        'local_pk' => null,

        /*
         * Passphrase for your local_cert file.
         */