You may decide to allow the internet to access certain ports on your OCI instance's public ip interface.

First, allow the access in Oracle OCI management console:

• Select your instance
• Under Instance details, go to Virtual cloud network and select the one used by the instance)
• Find the applicable Subnet in the table at the bottom. Click the subnet attached to the instance
• Find the applicable Security List in the table at the bottom. Click the security list attached to the instance
• Add a new Ingress rule with source 0.0.0.0/0, TCP protocol, Destination port 80 (or whatever, just change the port nginx listens on, which I won't cover here), add a description if you like.

Now that this is in place, you still need to allow the port access on the host itself. Good old iptables:

sudo iptables -I INPUT 6 -m state --state NEW -p tcp --dport 80 -j ACCEPT

And make it persistent after reboot:

sudo netfilter-persistent save

Test by hitting your host at http://yourhost.com

Now for the certbot stuff. Time for another snapshot.