How to install Discourse in the AWS EC2 Instances(Ubuntu Server LTS)?

First question, [at]Stephen told me, I need to:

because of I’m using Let’s Encrypt, and the reason is:

But, I rebooted Instance, configured DNS and without run command ./launcher rebuild app, the welcome page loaded successfully. So the question is how did it happened?


Second questions, how to auto renew Let’s Encrypt certificate?
Should I

like this Topic said(I’ve already using ./discourse-setup to enable Let’s Encrypt)?