Front Door with WordPress on Azure App Service

Here’s a quick overview of the steps you need to take to put Front Door in front of an Azure Web App. In this case, the web app runs a WordPress site.

Step 1: DNS

Suppose you deployed the Web App and its name is gebawptest.azurewebsites.net and you want to reach the site via wp.baeke.info. Traffic will flow like this:

user types wp.baeke.info ---CNAME to xyz.azurefd.net--> Front Door --- connects to gebawptest.azurewebsites.net using wp.baeke.info host header

It’s clear that later, in Front Door, you will have to specify the host header (wp.baeke.info in this case). More on that later…

If you have worked with Azure Web App before, you probably know you need to configure the host header sent by the browser as a custom domain on the web app. Something like this:

Custom domain in Azure Web App (no https configured – hence the red warning)

In this case, we do not want to resolve wp.baeke.info to the web app but to Front Door. To make the custom domain assignment work (because the web app will verify the custom name), add the following TXT record to DNS:

TXT awverify.wp gebawptest.azurewebsites.net 

For example in CloudFlare:

awverify txt record in CloudFlare DNS

With the above TXT record, I could easily add wp.baeke.info as a custom domain to the gebawptest.azurewebsites.net web app.

Note: wp.baeke.info is a CNAME to your Front Door domain (see below)

Step 2: Front Door

My Front Door designer looks like this:

Front Door designer

When you create a Front Door, you need to give it a name. In my case that is gebafd.azurefd.net. With wp.baeke.info as a CNAME for gebafd.azurefd.net, you can easily add wp.baeke.info as an additional Frontend host.

The backend pool is the Azure Web App. It’s configured as follows:

Front Door backend host (only one in the pool); could also have used the Azure App Service backend type

You should connect to the web app using its original name but send wp.baeke.info as the host header. This allows Front Door to connect to the web app correctly.

The last part of the Front Door config is a simple rule that connects the frontend wp.baeke.info to the backend pool using HTTP only.

Step 3: WordPress config

With the default Azure WordPress templates, you do not need to modify anything because wp-config.php contains the following settings:

define('WP_SITEURL', 'http://' . $_SERVER['HTTP_HOST'] . '/');                                                        define('WP_HOME', 'http://' . $_SERVER['HTTP_HOST'] . '/');

If you want, you can change this to:

define('WP_SITEURL', 'http://wp.baeke.info/' );                                                                         define('WP_HOME', 'http://wp.baeke.info/');   

Step 4: Blocking access from other locations

In general, you want users to only connect to the site via Front Door. To achieve this, add the following access restrictions to the Web App:

Access restrictions to only allow traffic from Front Door and Azure basic infrastructure services

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s