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meilon
Asked: 2022-10-27 22:42:08 +0800 CST

nginx to not modify query only redirect for reverse proxy

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I have to put a nginx reverse proxy in front of a web service for TLS termination which does 302 redirection only with query part of the URI:

GET /path/to/document?query=1
Host: 127.0.0.1

Returns 302 with 
Location: ?query=2

nginx always builds the full URI but omitting the document, therefore the redirects don't work

GET /path/to/document?query=1
Host: example.com

Returns 302 with 
Location: https://example.com/path/to/?query=2

I tried with proxy_redirect off;, but that doesn't change anything. What am I doing wrong?

Here's the config I currently use:

location / {
    client_max_body_size 50M;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    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_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Forwarded-Ssl on;
    proxy_set_header X-Frame-Options SAMEORIGIN;
    proxy_pass http://ip.of.the.host/;
    proxy_redirect off;
}

I could set proxy_redirect ~\?(.*)$ https://example.com/path/to/document?$1; but I'm sure I'll break something else.

How can I make nginx to just reply with the same Location path the upstream server does?

nginx nginx-reverse-proxy

1 Answers

  1. Best Answer

    Thanks to @Tero Kilkanen I did a tcpdump on the nginx server and found out the upstream server was actually providing the wrong Location header.

    After going through every header nginx sent to the upstream server and I still didn't get the same answer via curl I finally found the culprit: HTTP version!

    nginx uses http/1.0 per default, and curl uses http/1.1, that's why in my previous testing this never came up.

    Setting proxy_http_version 1.1; fixes the problem!

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