Proxy module buffering and timeouts

Fri Sep 4 12:42:54 UTC 2015

Given the following nginx config:

---
master_process off;

daemon off;

events {
  worker_connections 16384;
}

http {
  error_log stderr debug;
  access_log on;
  log_not_found on;
  client_body_buffer_size 64k;
  client_body_in_single_buffer on;

  upstream nodes {
    server 127.0.0.1:8000 max_fails=0;
    server 127.0.0.1:8001 max_fails=0;
    server 127.0.0.1:8002 max_fails=0;

    keepalive 16384;
  }

  server {
    listen *:7070 backlog=16384 reuseport;
    keepalive_requests 2147483647;

    location /demo {
      proxy_pass http://nodes;
      proxy_connect_timeout 1ms;
      proxy_read_timeout 1ms;
      proxy_send_timeout 1ms;
      proxy_buffering on;
    }
  }
}
---

When requesting nginx server I get either the response from the upstream
server:

curl -i http://localhost:7070/demo

HTTP/1.1 200 OK
Server: nginx/1.9.4
Date: Fri, 04 Sep 2015 12:33:00 GMT
Content-Type: text/plain
Content-Length: 27
Connection: keep-alive

{"message": "Hello World!"}

or a timeout response:

curl -i http://localhost:7070/demo

HTTP/1.1 504 Gateway Time-out
Server: nginx/1.9.4
Date: Fri, 04 Sep 2015 12:24:34 GMT
Content-Type: text/html
Content-Length: 182
Connection: keep-alive

<html>
<head><title>504 Gateway Time-out</title></head>
<body bgcolor="white">
<center><h1>504 Gateway Time-out</h1></center>
<hr><center>nginx/1.9.4</center>
</body>
</html>

but also i sometimes randomly get partially cut responses:

curl -i http://localhost:7070/demo

HTTP/1.1 200 OK
Server: nginx/1.9.4
Date: Fri, 04 Sep 2015 12:24:35 GMT
Content-Type: text/plain
Content-Length: 27
Connection: keep-alive

curl: (18) transfer closed with 27 bytes remaining to read

How this can be fixed? Since proxy buffering is on, i expect nginx always
return either  502 error page on upstream timeout or a response from an
upstream.

Here's a simple nodejs script of upstream nodes to reproduce the case:

var http = require('http');
var util = require('util');
var cluster = require('cluster');

var SERVER_COUNT = 8;
var HELLO_WORLD = '"message": "Hello World!"}';
var LOCALHOST = '127.0.0.1';
var PORT = 8000;

function simple(request, response) {
  response.writeHead(200, {
    'Content-Type': 'text/plain',
    'Content-Length': HELLO_WORLD.length + 1
    });
  response.write('{');
  response.end(HELLO_WORLD);
}

function createServer(port, handler) {
  http.createServer(handler).listen(port, LOCALHOST);
  util.log(util.format('Server running at http://%s:%d/', LOCALHOST,
port));
}

if (cluster.isMaster) {
  for (var c = 0; c < SERVER_COUNT; c++) {
    cluster.fork({
      port: PORT + c
    })
  }
} else {
  createServer(process.env.port, simple);
}

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,261424,261424#msg-261424