How do you rewrite Azure image URLs with data from the query string

Question

I have an Azure website hosting a set of images I use for Live Tiles in a Windows Phone app

The Live Tile image request encodes scale (and other) data in the URL something like this (I think, there is a terrible lack of documentation on this)

http://example.com/Images/sunny.png?ms-scale=100&ms-contrast=standard&ms-lang=en-us

I want to rewrite this to

http://example.com/Images/sunny.scale-100.png

Where the .scale-xxx value matches the value in the query string

Answer 1

I've figured it out after a rather large amount of searching

<system.webServer>
    <rewrite>
      <rules>
        <rule name="SpecificRewrite" stopProcessing="true">
          <conditions>
              <add input="{QUERY_STRING}" pattern=".*ms-scale=(\d+).*"  />
          </conditions>
          <match url="^Images/(.*).png.*" />
          <action type="Rewrite" url="/Images/{R:1}.scale-{C:1}.png" />
        </rule>
      </rules>
    </rewrite>
</system.webServer>

This adds the query string into the match (group referenced as C:1)

<add input="{QUERY_STRING}" pattern=".*ms-scale=(\d+).*"  />

This is the actual match (group referenced as R:1)

<match url="^Images/(.*).png.*" />

This is the rewrite rule

<action type="Rewrite" url="/Images/{R:1}.scale-{C:1}.png" />

Useful References

• URL Rewrite Module Configuration Reference
• Debug and troubleshoot rewrite rules easily

You can turn on Failed Request Tracing in the Configuration section in the Azure Website Management Portal, files end up in /LogFiles/<SiteName>/