Making sense of our template

So far, we have created a VPC with a single subnet. While we played around with master-slave instances and dependencies between them, these were just temporal changes to show how Terraform handles these use cases. Now it's time to add more meat to the template: let's create an instance with a security group attached to it.

Let's say we have a web application named MightyTrousers and we need a server for this, protected from unwanted traffic by a security group:

resource "aws_security_group" "allow_http" { 
  name = "allow_http" 
  description = "Allow HTTP traffic" 
  vpc_id = "${aws_vpc.my_vpc.id}" 
 
  ingress { 
    from_port = 80 
    to_port = 80 
    protocol = "tcp" 
    cidr_blocks = ["0.0.0.0/0"] 
  } 
 
  egress { 
    from_port = 0 
    to_port = 0 
    protocol = "-1" 
    cidr_blocks = ["0.0.0.0/0"] 
  } 
} 
 
resource "aws_instance" "mighty-trousers" { 
  ami = "ami-9bf712f4" 
  instance_type = "t2.micro" 
  subnet_id = "${aws_subnet.public.id}" ...