How to Redirect traffic from an App Service(Windows) to another Domain – Too Many Redirects Issue

Hello, today we are going to learn how to redirect the traffic from an App Service running on a Windows App Service Plan. Since Windows App Services have an underlying web server called IIS(Internet Information Services, usually used on Windows Server). The mechanism that we can “access to the configuration” and make changes to this IIS Web Server is by using the configuration file called “web.config”

“The web.config is a file that is read by IIS and the ASP.NET Core Module to configure an app hosted with IIS.”

Documentation:
web.config file | Microsoft Docs

Let’s begin. I have a WordPress App Service which I implemented a custom domain called “guidesforeveryone.com”, also I have set the subdomain “www” for this WordPress App.

This meaning that I have two custom domains: www.guidesforeveryone,com and guidesforeveryone.com(naked domain)
By doing this, I may be facing some conflict or “Too Many Redirects” issue, also we can be hurting our SEO due to Duplicate Content Indexing for Google: Avoid Duplicate Content | Google Search Central  |  Google Developers

Based on LiquidWeb:

The error “too many redirects” means that the website keeps being redirected between different addresses in a way that will never complete. Often this is the result of competing redirects, one trying to force HTTPS (SSL) and another redirecting back to HTTP (non-SSL), or between www and non-www forms of the URL.

As this is a persistent issue, the best solution for me is to decide to choose between the naked domain. or the “www” subdomain to use.

In my case, I will prefer the naked domain, due to Azure offers me a fully App Service Managed SSL Certificate for free, for only the naked domain. For further information about this, you can find information in this docs: Add and manage TLS/SSL certificates – Azure App Service | Microsoft Docs

So, since I have already chosen the naked domain, now we have to configurate the IIS to perform the redirect of my sites. We don’t configure the .htaccess file, due to this is a configuration for an Apache Server. Remember, Windows App Services uses IIS

For that, go to your App Service in the Azure Portal> Advanced Tools:

It will Display Kudu Site(CSM):

Click over Debug Console>CMD. It will display a directory like this:

Here you click over the “site” folder and the press the plus sign that over the content box
Then select “new file” and type “applicationHost.xdt” and press enter

Now this sign appears in the file:

You click over the pencil and it will open you a notepad, here you are going to copy and paste this:

XML configuration:

<?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" />  
	</system.webServer>  
</configuration>

Then you press save and now inside the “sites” folder click over the folder “wwwroot”.
Inside “wwwroot” folder there is a file called “web.config”, you have to click over the pencil again to modify the file.

If you do not have a “web.config” file, create a new one and paste the following:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
 <system.webServer>
  <rewrite>
      <rules>
        <rule name="Redirect" stopProcessing="true">
          <match url="(.*)" />
          <conditions logicalGrouping="MatchAny">
          <add input="{HTTP_HOST}" pattern="^www.guidesforeveryone\.com$" /> <!-- here you put the pattern in order to match the rule -->
          </conditions>
          <action type="Redirect" url="https://guidesforeveryone.com/{R:0}"/>  <!-- Here you put the URL that you want to redirect -->
        </rule>
      </rules>
    </rewrite>
</system.webServer>
</configuration>

And then press save. With this configuration your app should redirect you from www.guidesforeveryone.com to guidesforeveryone.com automatically.

Then, if you already have the web.config file please make sure to paste the following part of code between the configuration tag(block):

Like in the following image, we just pasted the script between the configurations tags(modules, block), without touching any another block in there(Block A and Block B are totally different but both blocks belongs to the configuration module):

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
 <system.webServer>
  <rewrite>
      <rules>
        <rule name="Redirect" stopProcessing="true">
          <match url="(.*)" />
          <conditions logicalGrouping="MatchAny">
          <add input="{HTTP_HOST}" pattern="^www.guidesforeveryone\.com$" /> <!-- here you put the pattern in order to match the rule -->
          </conditions>
          <action type="Redirect" url="https://guidesforeveryone.com/{R:0}"/>  <!-- Here you put the URL that you want to redirect -->
        </rule>
      </rules>
    </rewrite>
</system.webServer>
</configuration>

When it’s done, then click on save and restart you app service after that clean your browser(in order to delete cookies and cache) and then try to access to the App Service URL (in my case unsecured [non-SSL] www.guidesforeveryone.com) and check it takes you to the desired redirected site/domain (in my case secured SSL https://guidesforeveryone.com)

If you have any further questions or concerns, please feel free to contact me.  I am always glad to advise!

Thanks for reading my blog 🙂

Dorian Isaac Vallecillo Calderón
LinkedIn Profile: https://www.linkedin.com/in/dorianivc/
Email: dorianivc1@gmail.com