Overview

A demo to show the differences between Ansible and Terraform

Instructions

Export the environment variables for AWS

export AWS_ACCESS_KEY_ID=
export AWS_SECRET_ACCESS_KEY=

Ansible Demo

Run the Playbook

Change directory to the Ansible folder.

cd Ansible
ansible-playbook playbook_create.yml

Go to the EC2 instance and check the output.

Destroy the Environment

ansible-playbook playbook_destroy.yml

Terraform Demo

Run the Terraform

Change directory to the Terraform folder.

cd Terraform
terraform init
terraform plan
terraform apply

Destroy the Environment

terraform destroy

Differences to Notice

In Ansible:

1. Order matters If you put the launch of the EC2 instance before creating the key pair, it will fail to create the EC2 instance

2. Can't add tags after the EC2 instance is Created Since there is no state file, you can't make that change. Ansible doesn't detect the change.

3. Creation outside of Ansible is Considered If you create an EC2 instance from the AWS console in the same region, VPC, availability zone, and with a public IP. Basically it needs to have very similar config to the instance that Ansible created. Ansible is configured for a certain number of EC2 instances and will count the one created from the console. This can have strange and unpredictable effects.

Example: If you had a count of 2 and then create a 3rd instance outside of Ansible via the console, then run Ansible again with the same count of 2, Ansible will delete the latest instance it created. So it will take into account the instance created outside of Ansible.

4. Need to Create a Separate Playbook To Destroy In Ansible, you can't just destroy the infrastructure with the same playbook you used to create because there is no saved state. So you need to create another playbook to destroy the resources created. You also need to delete things in reverse order to how you created them.