Terraform code (resources.tf)

Note

Please refer to: https://github.com/PacktPublishing/Implementing-DevOps-on-AWS/blob/master/5585_06_CodeFiles/Terraform/resources.tf .

We add a second public and a matching private subnet so that we can distribute the production instances across multiple availability zones.

The aws_subnet resource creates a subnet named public-2. It takes attributes such as a VPC ID, CIDR BLOCK and AZs, the values of which we pull from variables. To compute the CIDR and AZ values we use Terraform's interpolation functions (ref: https://www.terraform.io/docs/configuration/interpolation.html):

resource "aws_subnet" "public-2" { 
  vpc_id = "${aws_vpc.terraform-vpc.id}" 
  cidr_block = "${cidrsubnet(var.vpc-cidr, 8, 3)}" 
  availability_zone = "${element(split(",",var.aws-availability-zones), count.index + 1)}" 
  map_public_ip_on_launch = true 
 
  tags { 
    Name = "Public" 
  } 
} 
 

Next, we...