chapter21
<html>
<head><title>502 bad gateway</title></head>
<body>
<center><h1>502 bad gateway</h1></center>
<hr><center>nginx</center>
</body>
</html>
<html>
<head><title>502 bad gateway</title></head>
<body>
<center><h1>502 bad gateway</h1></center>
<hr><center>nginx</center>
</body>
</html>