[SOLVED] reverseProxy: how to change content in embedded JavaScript file

Issue

I use Apache HTTP 2.4 as a reverse proxy. My configuration works fine except one thing:

• I would like to change a string content (url) in an embedded JavaScript file

This is my actual virtual host configuration:

<VirtualHost web.mydomain.com:80>
      ServerName web.mydomain.com
      ServerAlias web.mydomain.com

      DocumentRoot "..."
      ...

      RewriteEngine On
      RewriteCond %{REQUEST_METHOD} OPTIONS
      RewriteRule ^(.*)$ $1 [R=200,L]
      
      #Options -Indexes
      #ProxyRequests On
      #ProxyPreserveHost Off

      # Web App
      ProxyPass /hello http://middleware.mydomain.com:8082/hello-world-0.0.7
      ProxyPassReverse /hello http://middleware.mydomain.com:8082/hello-world-0.0.7
      
      AddOutputFilterByType SUBSTITUTE text/html
      Substitute "s|hello-world-0.0.7|hello|ni" 
</VirtualHost>

Could you please help me?

Solution

Usually, you should be able to configure the external URL in your application server, thereby eliminating the need to do the substitution in your Apache server. Such a configuration would be more efficient.

Did you validate in your browser that the returned Content-Type matches your filter? You indicate a Javascript file but filter for text/html. (e.g. Chrome: open Developer tools > navigate to the page > open Network tab > click on the resource that needs substitution > Look for the Content-Type header in the response headers). The Content-Type header should match your filter.

If it still does not work, it is likely that the application server returns gzipped content (check for Content-Encoding: gzip in the response headers). In that case, it makes sense that substitution won't work.

To work around that, add the following directive in your Apache configuration:

RequestHeader unset Accept-Encoding

Please note that this results in a performance penalty since more data needs to be sent across the network. I won't recommend this solution in a production environment since it applies to all requests for the current Virtual Host. If you only need to use substitution for a single file, I recommend wrapping the AddOutputFilterByType, Substitute and RequestHeader directives in a block, so that Apache only does the additional work for that file:

<Location "/hello/path/to/your/javascript/file.js">
  RequestHeader unset Accept-Encoding
  AddOutputFilterByType SUBSTITUTE text/html
  Substitute "s|hello-world-0.0.7|hello|ni" 
</Location>

Answered By - oneton

Answer Checked By - Willingham (WPSolving Volunteer)