Requirements

Write IaC script for provision of a 3-tier application in AWS. You can choose Terraform or CloudFormation to provide the infrastructure. Terraform is most preferred tool. Your code should provision the following:

• VPC with a public and private subnet.
• Route tables for each subnet, private subnet shall have a NAT gateway.
• Application tier and data tier shall be launched in private subnet.
• Web-tier shall be launched in public subnet.
• Web-tier and application-tier both must have autoscaling enabled and shall be behind an ALB
• Proper security groups attached across all the tiers for proper communication.

Bonus points will be given to the assignment with following items:

• Proper DNS mappings with a privately hosted zone in Route53 for application and data-tier.
• IAM roles attached to the application tier to access RDS, CloudWatch and s3 bucket.

Delivery Outcome:

• Once the IaC script is executed, it should create a VPC with valid CIDR block, which contains all VPC related Resources such as valid subnets, route tables (public, private), security groups, NAT gateway, Internet Gateway etc.
• It should also create EC2 servers for application-tier and web-tier with autoscaling groups and ALB, and RDS instances for data-tier.
• Proper security groups and IAM roles should be in place.

Manual Provisioning

Multiple environment state can be manage through Terraform workspace.

1. Create a new workspace for your project environment.

   terraform workspace new <project environment>

2. Initialize the Terraform environment.

   terraform init

3. Create new variables file for your new environment with the command below and update the value.

   cp terraform.tfvars.example terraform.tfvars

4. Apply the Terraform configuration to provision the infrastructure.

   terraform apply -var="name=<project name>" -var="environment=<project environment>"

   Note: You can use -auto-approve to skip the interactive confirmation.

5. Tear down the infrastructure with Terraform destroy command.

   terraform destroy -var="name=<project name>" -var="environment=<project environment>"

Automated Provisioning

Automated provisioning can be done through Github Actions workflow.