Rewriting a URL in an Azure web app

You need to create a web.config file in your wwwroot folder and put the relevant config entries there.

Here's an example of an web.config rule, to give you an idea of what it should look like.

The below example redirect the default *.azurewebsites.net domain to a custom domain (via http://zainrizvi.io/blog/block-default-azure-websites-domain/)

<configuration>
  <system.webServer>  
    <rewrite>  
        <rules>  
          <rule name="Redirect rquests to default azure websites domain" stopProcessing="true">
            <match url="(.*)" />  
            <conditions logicalGrouping="MatchAny">
              <add input="{HTTP_HOST}" pattern="^yoursite\.azurewebsites\.net$" />
            </conditions>
            <action type="Redirect" url="http://www.yoursite.com/{R:0}" />  
          </rule>  
        </rules>  
    </rewrite>  
  </system.webServer>  
</configuration>

If simply want all URL's that resolve to this server & site to redirect to index.html you could use this rewrite section:

<configuration>
    <system.webServer>
        <rewrite>
            <rules>
                <rule name="SPA">
                    <match url=".*" />
                    <action type="Rewrite" url="index.html" />
                </rule>
            </rules>
        </rewrite>
    </system.webServer>
</configuration>

This is very similar to what you have except some minor syntax fixes e.g. the pattern should be ".*" and the rewrite URL target simply "index.html". Note this means that ALL URL's to your site will be rewritten, even for other resources like CSS and JS files, images etc. So you'd better be fetching your resources from other domains.

If you want to do actual rewrites (not redirects), dont forget enabling ARR with applicationHost.xdt file put to the site folder with the following content:

<?xml version="1.0"?>
<configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
  <system.webServer>
    <proxy xdt:Transform="InsertIfMissing" enabled="true" preserveHostHeader="false" reverseRewriteHostInResponseHeaders="false" />
    <rewrite>
      <allowedServerVariables>
        <add name="HTTP_ACCEPT_ENCODING" xdt:Transform="Insert" />
        <add name="HTTP_X_ORIGINAL_HOST" xdt:Transform="Insert" />
      </allowedServerVariables>
    </rewrite>
  </system.webServer>
</configuration>