NGINX: upstream timed out (110: Connection timed out) while reading response header from upstream

Question

I have Puma running as the upstream app server and Riak as my background db cluster. When I send a request that map-reduces a chunk of data for about 25K users and returns it from Riak to the app, I get an error in the Nginx log:

upstream timed out (110: Connection timed out) while reading response header from upstream

If I query my upstream directly without nginx proxy, with the same request, I get the required data.

The Nginx timeout occurs once the proxy is put in.

**nginx.conf**

http {
    keepalive_timeout 10m;
    proxy_connect_timeout  600s;
    proxy_send_timeout  600s;
    proxy_read_timeout  600s;
    fastcgi_send_timeout 600s;
    fastcgi_read_timeout 600s;
    include /etc/nginx/sites-enabled/*.conf;
}

**virtual host conf**

upstream ss_api {
  server 127.0.0.1:3000 max_fails=0  fail_timeout=600;
}

server {
  listen 81;
  server_name xxxxx.com; # change to match your URL

  location / {
    # match the name of upstream directive which is defined above
    proxy_pass http://ss_api; 
    proxy_set_header  Host $http_host;
    proxy_set_header  X-Real-IP  $remote_addr;
    proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_cache cloud;
    proxy_cache_valid  200 302  60m;
    proxy_cache_valid  404      1m;
    proxy_cache_bypass $http_authorization;
    proxy_cache_bypass http://ss_api/account/;
    add_header X-Cache-Status $upstream_cache_status;
  }
}

Nginx has a bunch of timeout directives. I don't know if I'm missing something important. Any help would be highly appreciated....

Answer 1

This happens because your upstream takes too much to answer the request and NGINX thinks the upstream already failed in processing the request, so it responds with an error. Just include and increase proxy_read_timeout in location config block. Same thing happened to me and I used 1 hour timeout for an internal app at work:

proxy_read_timeout 3600;

With this, NGINX will wait for an hour (3600s) for its upstream to return something.