I have a multi-site Drupal 7 install running on Azure that I would like to force all non-www traffic to the www address for all sites.

I have tried a number of examples from around the web but none of them seem to work.

Here is my current implementation, which looks like it should work, but does nothing.

    <rule name="Redirect to www">
      <match url=".*" />
      <conditions logicalGrouping="MatchAny">
        <add input="{HTTP_HOST}" pattern="^(www\.)(.*)$" negate="true" />
      </conditions>
      <action type="Redirect" url="http://www.{HTTP_HOST}/{R:0}" redirectType="Permanent"/>
    </rule>

To clarify, yes, the above rule is nested inside `<configuration> <system.webServer> <rewrite>`

I've read about doing the redirect in settings.php but that seems kludgy to me and I'd rather do it right.

Any help would be greatly appreciated.