What is the proper way to set up an AWS Auto-Scale group?
Drupal considerations are similar to WP, Magento and Stateless applications.


Share your code across your auto scaling group via AWS EFS, Lsyncd, S3 or NFS.
Use CDN + S3 for static content
Separate Database (AWS RDS)
Make sure to use Varnish and NGINX.
Use Github/BitBucket and define a development workflow system.
Cache and manage session via Redis/Memcached.


More details: https://www.clickittech.com/cloud-computing/scaling-in-the-cloud/

The above link is an article about the Art of scaling which considers Drupal, WP and Saas Applications.