terraform, then ansible

Terraform creates the infra, 

then we want to use ansible to actually configure it...

Different solutions exist to run Terraform, and them ansible:

• Using Terraform Output as Ansible Inventory :
  https://github.com/adammck/terraform-inventory
   $ terraform-inventory -inventory terraform.tfstate [all] 10.10.1.2 10.10.1.3
  
  
  
• `local-exec` / `remote-exec` : terraform runs ansible locally 
  
   ``` provisioner "local-exec" {command = "ANSIBLE_HOST_KEY_CHECKING=False ansible-playbook -u {var.user} -i '${self.ipv4_address},' --private-key ${var.ssh_private_key} playbook.yml"} ```
  

  key component here is the ${self.ipv4_address} variable. After provisioning the machine, Terraform knows its IP address. And we need to pass an IP address for Ansible.

   (cf https://www.cprime.com/resources/blog/terraform-and-ansible-tutorial-integrating-terraform-managed-instances-with-ansible-control-nodes )

   

• using dynamic inventory and cloud providers specific ansible modules 

•  AWS : https://docs.ansible.com/ansible/latest/collections/amazon/aws/aws_ec2_inventory.html 
•  GCP : https://docs.ansible.com/ansible/latest/collections/google/cloud/gcp_compute_inventory.html#ansible-collections-google-cloud-gcp-compute-inventory and so on...

AWS example of the dynamic inventory:

ansible.cfg :

enable_plugins=aws_ec2

aws_ec2.yml (example):

plugin: aws_ec2

regions:

  - "us-east-1"

keyed_groups:

  - key: tags.Name

  - key: tags

    prefix: tag

  - prefix: instance_type

    key: instance_type

  - key: placement.region

    prefix: aws_region

filters:

  instance-state-name : running

  # All instances with their `Environment` tag set to `dev`

  tag:Environment: dev

  # All dev and QA hosts

  tag:Environment:

    - dev

    - qa

compose:

  ansible_host: public_ip_address

Good way to test : 

ansible-inventory -i aws_ec2.yml --graph

ansible all –list-hosts

To run a playbook have/generate 4 files : myplaybook.yml, key.pem, aws_ec2.yml (seen before), and ansible.cfg (seen after)

ansible.cfg

[defaults]
inventory=./aws_ec2.yml

host_key_chekcing=false

remote_user=ec2-user

private_key_file=key.pem

[privilege_escalation]

become=true

become_method=sudo

become_user=root

Run 

ansible <group-name> -i aws_ec2.yaml -m ping --private-key=<private-key-name> 

ansible-playbook myplaybook.yml

 (with hosts: _Ansible_TargetNode or whatever you have validated in the output of the inventory)

# sources : 

https://www.cloudthat.com/resources/blog/step-by-step-guide-to-integrate-ansible-dynamic-inventory-plugin-for-aws-ec2-instances#why-ansible-dynamic-inventory-

https://medium.com/geekculture/a-complete-overview-of-ansible-dynamic-inventory-a9ded104df4c