An easy ec2 instance with ssh access, inspired by https://bit.ly/3mbgc35

ec2-instance.tf

variable "ami_name" {
  default = "Amazon Linux 2 AMI "
}
variable "ami_id" {
  default = "ami-0d26eb3972b7f8c96"
}
variable "ami_key_pair_name" {
  default = "el-test"
}

//subnets.tf
resource "aws_subnet" "subnet-uno" {
  cidr_block = "${cidrsubnet(aws_vpc.test-env.cidr_block, 3, 1)}"
  vpc_id = "${aws_vpc.test-env.id}"
  availability_zone = "eu-west-2a"
}

//security.tf
resource "aws_security_group" "ingress-all-test" {
name = "allow-all-sg"
vpc_id = "${aws_vpc.test-env.id}"
ingress {
    cidr_blocks = [
      "0.0.0.0/0"
    ]
    from_port = 22
    to_port = 22
    protocol = "tcp"
  }

ingress {
    cidr_blocks = [
      "0.0.0.0/0"
    ]
    from_port = 0
    to_port = 0
    protocol = "-1"
  }
// Terraform removes the default rule
  egress {
   from_port = 0
   to_port = 0
   protocol = "-1"
   cidr_blocks = ["0.0.0.0/0"]
 }
}

//servers.tf
resource "aws_instance" "test-ec2-instance" {
  ami = "${var.ami_id}"
  instance_type = "t2.medium"
  key_name = "${var.ami_key_pair_name}"
  security_groups = ["${aws_security_group.ingress-all-test.id}"]

  subnet_id = "${aws_subnet.subnet-uno.id}"

  tags = {
    Name = "${local.identifier_prefix}-Data-hub"
  }
}

resource "aws_vpc" "test-env" {
  cidr_block = "10.0.0.0/16"
  enable_dns_hostnames = true
  enable_dns_support = true

}
resource "aws_eip" "ip-test-env" {
  instance = "${aws_instance.test-ec2-instance.id}"
  vpc      = true
}

//gateways.tf
resource "aws_internet_gateway" "test-env-gw" {
  vpc_id = "${aws_vpc.test-env.id}"

}

//subnets.tf
resource "aws_route_table" "route-table-test-env" {
  vpc_id = "${aws_vpc.test-env.id}"
  route {
      cidr_block = "0.0.0.0/0"
      gateway_id = "${aws_internet_gateway.test-env-gw.id}"
    }
}
resource "aws_route_table_association" "subnet-association" {
  subnet_id      = "${aws_subnet.subnet-uno.id}"
  route_table_id = "${aws_route_table.route-table-test-env.id}"
}