When deploying compute instances at Oracle Cloud Infrastructure you need to take into account few things:
- Create Internet Gateway (IGW).
- Define routes to point to IGW.
- Allow port 80 in the Security List associated with the IGW. By default you only have access to SSH and ICMP 3,4 type.
- Allow connectivity on Compute's instance firewall (which is enabled by default).
In your example if you are using a OEL shape:
$ sudo firewall-cmd --zone=public --permanent --add-port=80/tcp
$ sudo firewall-cmd --reload