HOW TO : Configure nginx to use URI for modifying response content

That was a pretty long title for the post :). I love nginx for it’s flexibility and ease of use. It is like a swiss army knife.. can do a lot of things :).

We needed to serve some dynamic content for one of our use cases. If user visits a site using the following URL format http://example.com/23456789/678543 , we want to respond with some html content that is customized using the 23456789 and 678543 strings.

A picture might help here

Here’s how this was achieved

  • Define a location section in the nginx config to respond to the URL path specified and direct it to substitute content
    location ~ "^/(?<param1>[0-9]{8})/(?<param2>[0-9]{6})" {

            root /var/www/html/test/;
            index template.html;
            sub_filter_once off;
            sub_filter '_first_param_' '$param1';
            sub_filter '_second_param_' '$param2';
            rewrite ^.*$ /template.html break;
    }

create a file named template.html with the following content in /var/www/html/test

Breaking down the config one line at a time

location ~ "^/(?<param1>[0-9]{8})/(?<param2>[0-9]{6})" : The regex is essentially matching for the first set of digits after the / and adding that as the value for variable $param1. The first match is a series of 8 digits with each digit in the range 0-9. The second match is for a series of 6 digits with each digit in the range 0-9 and it will be added as the value for variable $param2

root /var/www/html/test/; : Specifying the root location for the location.

index template.html; : Specifying the home page for the location.

sub_filter_once off; : Specify to the sub_filter module to not stop after the first match for replacing response content. By default it processes the first match and stops.

sub_filter 'first_param' '$param1'; : Direct the sub_filter module to replace any text matching first_param in the response html with value in variable $param1.

sub_filter 'second_param' '$param2'; : Direct the sub_filter module to replace any text matching second_param in the response html with value in variable $param1.

rewrite ^.*$ /template.html break; : Specify nginx to server template.html regardless of the URI specified.

Big thanks to Igor for help with the configs!!

One Reply to “HOW TO : Configure nginx to use URI for modifying response content”

  1. If you want to make the URL case insensitive. Add a * after the ~.

    location ~* “^/(?[0-9]{8})/(?[0-9]{6})” {

    root /var/www/html/test/;
    index template.html;
    sub_filter_once off;
    sub_filter ‘_first_param_’ ‘$param1’;
    sub_filter ‘_second_param_’ ‘$param2’;
    rewrite ^.*$ /template.html break;
    }

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