Rewrite rules

• Return back to the reverse-proxy main section

Rewrite rules modify part or all of the URL path in the user's request.
usually for one of two purposes:

• Inform browsers that the resource they're requesting is now in a different location. 
  When your website's domain name has changed, when you want customers to use a canonical URL format (with or without the www prefix), and when you want to detect and correct common spelling errors in your domain name. 
  The return and rewrite directives are ideal for these situations.
• To control the processing flow within the reverse-proxy.
  Example: To forward requests to an application server when content needs to be dynamically generated. 
   

Build a rewrite rule

• To build a rewrite rule, you have to select the website rule in the main table and choose the “Options” tab
• Click on the “Rewrite Rules” row in the Content Replacement section

• A new window appears, click on the "New rewrite rule" button

• Enter a description of the rule. 
  This text will help you remember and search for the rule in the list.

The Request field

• The request field expresses the request that will arrive at the reverse-proxy before being processed.
  This means that the path may not exist on your web server.
  For example, let's say that the urls /downloads, /dowanlad, /downlaod (with a bad spelling) must be understood by the real URL /download.php

There are 3 ways to represent these 3 source urls in this section

• Create 3 rules: one for /downloads, one for /dowanlad, one for /downlaod
• Use a single rule with a regular expression (if you're familiar with it) eg “^/(downloads|dowanlad|downlaod)”
• Use a single rule using list: as prefix and values speparated by a comma eg list:/downloads,/dowanlad,/downlaod

The Rewrite To field

This is the destination of the request, the one that must actually exist on your Web server.
If you're using a regular expression with groups, then it's possible to specify the group result with a dollar followed by the number corresponding to the group ($1, $2, $3...).

The Option field

The Option field let you select 4 ways:

1. Start at the new calculated location: This is the most common option, it stops current processing and starts the search for a new location corresponding to the modified URI, so you can specify a defined path , for example.
2. Stop rules processing: stops processing the current set ( similar to 1 but continues applies next other settings)
3. Permanent redirection: Return a 301 code and ask the browser to return back with the correct uri.
4. Temporary redirection: Return a 302 code and ask the browser to return back with the correct uri.

This is the rule that applies to the examples given in this article.

Another alternative is to use a regular expression