nginx load balancer cannot send "proxy_host" value correctly

mani

5/4/24, 11:31 AM

I want to use nginx load balancer. The domain servers used in the upstream section use a shared IP. Suppose the domain name of the load balancer server is load-balancer.com

upstream test_upstream {
      server upstream1.com;
      server upstream2.com;
}

and

location / {

              proxy_redirect off;
              proxy_http_version 1.1;
              proxy_set_header Upgrade $http_upgrade;
              proxy_set_header Connection "upgrade";

              proxy_pass http://test_upstream/;
              proxy_set_header Host $proxy_host;
          }

Because the domains use a shared IP, it is very important that the Host value is equal to upstream1.com or upstream2.com. But $proxy_host sets the Host value equal to the upstream name. (In this example, it sets test_upstream in Host). The header received in the upstream server is as follows:

065.227.015.247.39136-085.083.104.010.00080: GET / HTTP/1.1
Connection: upgrade
Host: test_upstream
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36 OPR/98.0.0.0
....

Also, using $host or $http_host instead of $proxy_host will also send the value of load-balancer.com as Host. Also, if $upstream_http_host or $upstream_http_server or $upstream_http_addr is used, a 404 error will occur. How to set the Host value correctly?

0 + 2

nginx

reverse-proxy

load-balancing

Gerald Schneider

5/4/24, 12:20 PM

If the upstream server share the same IP, what's the point in the load balancer in the first place?

mani

5/4/24, 2:05 PM

@gerald-schneider It is used in an anti-censorship method of the Internet

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: nginx load balancer cannot send "proxy_host" value correctly

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