Creating ec2 instances and installing mongoDB using automation I am trying to create a 3 node MongoDB replica set using automation (ansible or terraform) in AWS. I am able to do this in the management console of AWS, but I'm not sure how to approach it.

Essentially, the script must create the instances and then set up a 3 node MongoDB replica set on them. I want to add an EBS disk on it and then maybe secure it.

All of this via Ansible (or Terrafor) so I can automate it fully.

Is this possible?

Thanks!!
It's possible. I would use Terraform for creating the infrastructure on AWS and Ansible for provisioning. You will have to write .tf files and ansible-playbooks in order to do this. 

Just to let you know, if all 3 nodes are equal you should do the installation and provisioning once and then create an AMI to set up the rest. Maybe an autoscaling group is a possibility too. 

Keep in mind that AWS provides documentdb as document-oriented database as a service. It's not mongoDB but it's pretty similar (there are some functions mongo provides and docdb doesn't).