Use PANTHEON_HOSTNAME when setting SERVER_NAME

source/content/server_name-and-server_port.md

@@ -16,16 +16,18 @@ Some code relies on `$_SERVER['SERVER_NAME']` and `$_SERVER['SERVER_PORT']` to c
 
 In general, you don't want your code to rely on this, but some extensions (themes, modules, plugins) give you no choice. In that case, you will need to modify the `$_SERVER` variable in your `settings.php` (Drupal) or `wp-config.php` (WordPress) file to ensure the right values are present.
 
-## Use HTTP_HOST Instead of SERVER_NAME
+## Use PANTHEON_HOSTNAME Instead of SERVER_NAME
 
-`HTTP_HOST` is generated dynamically based on the current request, while `SERVER_NAME` is static. If the `$_SERVER`variable is set to `'SERVER_NAME'`, the URL generated for a request will be something similar to `https://endpoint05ccd237.chios.panth.io` instead of the intended `https://yourdomain.com`.
+`PANTHEON_HOSTNAME` is added in `wp-config-pantheon.php` and constructed from `HTTP_HOST` (if available) or the Pantheon environment if `HTTP_HOST` is unavailable (e.g. in WP-CLI). If the `$_SERVER`variable is set to `'SERVER_NAME'`, the URL generated for a request will be something similar to `https://endpoint05ccd237.chios.panth.io` instead of the intended `https://yourdomain.com`.
 
 Adding the following code will pass the correct value when `'SERVER_NAME'` is used:
 
 ```php
-$_SERVER['SERVER_NAME'] = $_SERVER['HTTP_HOST'];
+$_SERVER['SERVER_NAME'] = PANTHEON_HOSTNAME;
 ```
 
+`PANTHEON_HOSTNAME` can be overridden by defining the constant manually in your `wp-config.php` file before the `wp-config-pantheon.php` file is required as noted in the [`wp-config.php` documentation](/guides/php/wp-config-php#how-can-i-override-the-default-pantheon_hostname-value).
+
 While this fix does correct symptoms such as undesirable URLs, we recommended replacing all instances of `'SERVER_NAME'` with `'HTTP_HOST'` directly (e.g. [`WP_HOME` and `WP_SITE`](https://github.com/pantheon-systems/WordPress/blob/default/wp-config-pantheon.php#L52) for WordPress).
 
 <Alert title="Note" type="info">

source/content/wordpress-known-issues.md

@@ -307,7 +307,7 @@ ___
 **Solution:** Add the following to `wp-config.php`:
 
 ```php:title=wp-config.php
-$_SERVER['SERVER_NAME'] = $_SERVER['HTTP_HOST'];
+$_SERVER['SERVER_NAME'] = PANTHEON_HOSTNAME;
 
 if (isset($_ENV['PANTHEON_ENVIRONMENT'])) {
   if (isset($_SERVER['HTTP_USER_AGENT_HTTPS']) && $_SERVER['HTTP_USER_AGENT_HTTPS'] === 'ON') {
@@ -860,7 +860,7 @@ ___
   // server name and not the current hostname, as a
   // result, Redirection's "URL and server"-based
   // redirects never match.
-  $_SERVER['SERVER_NAME'] = $_SERVER['HTTP_HOST'];
+  $_SERVER['SERVER_NAME'] = PANTHEON_HOSTNAME;
   ```
 
 Visit the [SERVER_NAME and SERVER_PORT on Pantheon](/server_name-and-server_port) doc for more information about how to use `HTTP_Host` on Pantheon.
@@ -930,7 +930,7 @@ The plugin generates the site's URL using `$_SERVER['SERVER_NAME']` instead of `
 **Solution:** Add the following line to `wp-config.php`:
 
 ```php:title=wp-config.php
-$_SERVER['SERVER_NAME'] = $_SERVER['HTTP_HOST'];
+$_SERVER['SERVER_NAME'] = PANTHEON_HOSTNAME;
 ```
 
 ___