function isDocker() {
	var file;
	if ( exists( '/.dockerenv' ) ) {
		return true;
	}
	file = readFile( '/proc/self/cgroup', OPTS );
	if ( isError( file ) ) {
		return false;
	}
	return contains( file, 'docker' );
}
Returns a boolean indicating if the process is running in a Docker container.

@returns {boolean} boolean indicating if the process is running in a Docker container

@example
var bool = isDocker();
// returns <boolean>