nginx: Why I can't put proxy_set_header inside an if clause?

Question

With this configuration:

server {
    listen 8080;
    location / {
        if ($http_cookie ~* "mycookie") {
            proxy_set_header X-Request $request;
            proxy_pass http://localhost:8081;
        }
    }
}

I have this error when I reload nginx service:

Reloading nginx configuration: nginx: [emerg] "proxy_set_header" directive is not allowed here in /etc/nginx/conf.d/check_cookie.conf:5
nginx: configuration file /etc/nginx/nginx.conf test failed

This configuration works OK, but it does not do what I want:

server {
    listen 8080;
    location / {
        proxy_set_header X-Request $request;
        if ($http_cookie ~* "mycookie") {
            proxy_pass http://localhost:8081;
        }
    }
}

Why I can't put proxy_set_header directive inside an if clause?

Please don't cross-post. http://stackoverflow.com/questions/16500594/why-i-cant-put-proxy-set-header-inside-an-if-clause — ceejayoz, May 11 '13 at 19:14
I opened a chat to discuss about this. We can continue the discussion there: http://chat.stackexchange.com/rooms/8745/nginx — Neuquino, May 12 '13 at 14:54

score 18 · Accepted Answer · answered May 12 '13 at 02:30

18

Assuming you actually meant to ask, 'how can I get this to work', how about just re-writing so the header is always passed, but has it set to some ignored value if you don't want it set.

server {
    listen 8080;    
    location / {
        set $xheader "someignoredvalue";

        if ($http_cookie ~* "mycookie") {
            set $xheader $request;
        }

        proxy_set_header X-Request $xheader;

        if ($http_cookie ~* "mycookie") {
            proxy_pass http://localhost:8081;
        }
    }

answered May 12 '13 at 02:30

Danack

1,216
1
16
27

1

You mean `""`, right? – Michael Hampton May 12 '13 at 02:33
2

I personally prefer to set things to be obviously not a real value, rather than potentially forgetting that this hack was in place, and then wondering why the header was empty. If it's set to "X-Header-not-set-by-nginx" then you're never going to be confused. – Danack May 12 '13 at 02:51
1

According to this article: https://www.nginx.com/resources/wiki/start/topics/depth/ifisevil/. The only 100% safe things which may be done inside if in a location context are return and rewrite. I doubt the proxy_pass in if block will always work. – Chau Chee Yang May 03 '19 at 03:23
Danack thank you, it works. @MichaelHampton and thank you, yes it is!! :) – Jacky Supit Jul 21 '22 at 14:09

score 0 · Answer 2 · answered May 12 '13 at 01:16

0

'If' is generally a bad practive in nginx configuration. You can use map module to make things work. see http://nginx.org/en/docs/http/ngx_http_map_module.html http://wiki.nginx.org/HttpMapModule

answered May 12 '13 at 01:16

Drew Khoury

4,637
8
27
28

nginx: Why I can't put proxy_set_header inside an if clause?

2 Answers2