how to break a variable into seperate variables in nginx using regex

Question

I have a development server setup that does some dynamic rooting to allow me to set up quick test projects by detecting domain and subdomain in server_name and using it to set the root.

server_name ~^(?<subdomain>\w*?)?\.?(?<domain>\w+\.\w+)$;

This works well, allowing me to set the root path based on variables $subdomain and $domain

For a specific type of project though, I also need to be able to further split the subdomain variable into two variables base on if the subdomain contains a dash.

e.g.

mysubdomain should not split but remain as variable $subdomain,

but mysubdomain-tn would be seperated into 2 variable $subdomain and $version

Ivan Tsirulev · Accepted Answer · 2015-03-30 22:13:43Z

5

You need to complicate your regular expression a bit more:

server_name ~^(?<subdomain>\w*?)(-(?<version>\w*?)?)?\.?(?<domain>\w+\.\w+)$;

EDIT:

There are several ways to debug an Nginx configuration, including the debugging log, echo module and, in some extreme situations, even using a real debugger. However, in most cases adding custom headers to the response is enough to get the necessary information.

For example, I tested the regular expression above using this simple configuration:

server {
    listen 80;

    server_name ~^(?<subdomain>\w*?)(-(?<version>\w*?)?)?\.?(?<domain>\w+\.\w+)$;

    # Without this line your browser will try to download
    # the response as if it were a file
    add_header Content-Type text/plain;

    # You can name your headers however you like
    add_header X-subdomain "$subdomain";
    add_header X-domain "$domain";
    add_header X-version "$version";

    return 200;
}

Then I added domains mydomain.local, mysubdomain-tn.mydomain.local and mysubdomain-tn.mydomain.local to my hosts file, opened them in a browser with open debug panel (F12 in most browsers) and got the results.

edited Mar 30, 2015 at 22:13

answered Mar 30, 2015 at 20:37

Ivan Tsirulev

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3 Comments

Finglish Over a year ago

Thanks! I got close but I couldn't work out how to make the regex work with and without the dash. Not being able to easily inspect variables in ngix config makes it hard to debug. Any tips?

Ivan Tsirulev Over a year ago

@Finglish, I added some additional explanations to the original answer.

Rahim Khoja Over a year ago

Really Helpful! :)

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