AWS EC2 Instance with Security Group using Terraform

1. Create tf script.
flowchart TD; A[ssh-key]-->|login|B[EC2]; C[Security Group]-->|attach|B;

provider "aws" {
    region = "${var.AWS_REGION}"
}
resource "aws_key_pair" "example_key" {
    key_name = "mykey"
    public_key = "${file("${var.PATH_TO_PUBLIC_KEY}")}"
}

resource "aws_instance" "example" {
    ami = "${lookup(var.AMIS,var.AWS_REGION)}"
    instance_type = "t2.micro"
    security_groups = [aws_security_group.example_sg.name]
    key_name = "${aws_key_pair.example_key.key_name}"
    provisioner "file" {
        source  = "script.sh"
        destination = "/tmp/script.sh"
    }
    provisioner "remote-exec"{
        inline = [
            "chmod +x /tmp/script.sh",
            "sudo /tmp/script.sh"
        ]
    }
    connection {
        host = self.public_ip
        user = "${var.INSTANCE_USERNAME}"
        private_key = "${file("${var.PATH_TO_PRIVATE_KEY}")}"
    }
    provisioner "local-exec"{
        command = "echo ${aws_instance.example.public_ip} >> public_ips.txt"
    }
    tags = {
        Name = "ec2 example terraform instance"
    }
}

resource "aws_security_group" "example_sg" {
    name = "security group for example ec2"
    ingress {
        description = "HTTPS"
        from_port = 443
        to_port = 443
        protocol = "tcp"
        cidr_blocks = ["0.0.0.0/0"]
        ipv6_cidr_blocks = ["::/0"]
    }
    ingress {
        description = "HTTP"
        from_port = 80
        to_port = 80
        protocol = "tcp"
        cidr_blocks = ["0.0.0.0/0"]
        ipv6_cidr_blocks = ["::/0"]
    }
    ingress {
        description = "SSH"
        from_port = 22
        to_port = 22
        protocol = "tcp"
        cidr_blocks = ["0.0.0.0/0"]
        ipv6_cidr_blocks = ["::/0"]
    }

    egress {
        from_port = 0
        to_port = 0
        protocol = "-1"
        cidr_blocks = ["0.0.0.0/0"]
        ipv6_cidr_blocks = ["::/0"]
    }

    tags = {
        Name = "sg"
    }
}

output "ip" {
    value = "${aws_instance.example.public_ip}"
}
        

2. Generate ssh key. ssh-keygen mykey
3. Terraform apply.
4. ssh -i mykey ubuntu@ip

References