Nginx Question posted in
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NGINX add two variable/arguments numbers

I’m trying to set up an Nginx, where I want to add two numbers together.

server {
        server_name "~^pr-(d*).review-apps.example.com$";
        
        location / {
            set $port 50000+$1;
            proxy_pass "http://localhost:$port/test";
        }
    }

But this doesn’t work 🙄. (Result is in string. For example "50000+125")

How can I add two numbers in nginx.conf? Is it even possible?

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2

Answers


  1. 0

    No, it is not possible to use math with standard modules. There might be a chance with lua module but you probably shouldn’t as NGINX wasn’t meant to be used like that. It is like using a screwdriver to hammer a nail – it is possible that you succeed but it is also possible that you poke out an eye along the way.

    I suggest you reconsider the design of your application, perhaps there is a better/commonly used way to achieve what you want.

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  2. 0

    If you use fixed length numbers, for example only three digits, for this particular case you can use string concatenation instead of adding numbers:

    server {
    server_name "~^pr-(d{3}).review-apps.example.com$";
        
    location / {
        set $port 50$1;
        proxy_pass "http://localhost:$port/test";
    }
}

    This will give you exactly 50145 for the pr-125.review-apps.example.com hostname.

    For variable count of port number digits you can use named regex capture group:

    server {
    server_name  "~^pr-(?<pr1>d).review-apps.example.com$"
                 "~^pr-(?<pr2>d{2}).review-apps.example.com$"
                 "~^pr-(?<pr3>d{3}).review-apps.example.com$";

    location / {
        if ($pr1) { set $port 5000$pr1; }
        if ($pr2) { set $port 500$pr2; }
        if ($pr3) { set $port 50$pr3; }
        proxy_pass "http://localhost:$port/test";
    }
}
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