4.6 Apache Force Common URL

In some cases you want to force what a consistent url for a variety of reasons,

• Vendor or product code that works with only a specific url
• Improve index results from search engines
• Enforcing a www. points to a CNAME record and puts you in a better position for DDoS DNS mitigation with a CDN

This can be accomplished using Apache's Rewrite.

This website uses this feature where http://bonsaiframework.com will redirect to http://www.bonsaiframework.com

Enable Rewrite Module

With Ubuntu this is very easy,

sudo a2enmod

Will result in showing a list of modules that you can enable. You want to enable rewrite. If it is not there than it might already be enabled.

Verify Rewrite Module

It is actually somewhat difficult to verify that the module is loaded.

Apply Directives

# Enforce www in front of url.
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.bonsaiframework\.com$ [NC]
RewriteRule (.*) http://www.bonsaiframework.com$1 [R,L]

I usually place these rules right after my ServerAlias lines in my virtual host.

Debugging