Terraform

Frequently used terraform snippets

One-liners

Validate configurations: terraform validate

Start terraform config: terraform init

Give format to files within direcoty terrafom fmt

Execute terraform terraform apply --auto-approve

Frecuently used AMI IDs

• Ubuntu server 18.04 (HVM) 64bits x86: ami-0a63f96e85105c6d3

Recipes

Setup AWS instances

1. Get AWS access key/AWS secret key

2. execute aws configure using credentials from 1.

3. execute terraform init when starting new project at the root of the directory

Get list of AMI IDs matching criteria

variable "image_name" {
    description = "The name of the image to use"
    default = "ubuntu-*-18.04*"
}

provider "aws" {
    region = "us-east-2"
}

data "aws_ami" "images" {
    owners = ["amazon"]
    most_recent = true
    filter {
      name = "name"
      values = [var.image_name]
    }
}

output "ids" {
    value = "\nName: ${data.aws_ami.images.name}\nId: ${data.aws_ami.images.id}"

Single ec2 with ubuntu 18.04 x86

variable "key_name" {
    description = "Key to use for accessing the instance"
}

variable "sec_group" {
    description = "Security group for the instance"
}

variable "instance_name" {
    description = "Instance's name"
}

provider "aws" {
    region = "us-east-2"
}

resource "aws_instance" "example" {
	ami = "ami-f4f4cf91"
	instance_type = "t2.micro"
	key_name = var.key_name
	vpc_security_group_ids = var.sec_group
	tags = {
		Name = var.instance_name
	}
}

output "public_ip" {
    value = "Created instance (public_dns):  ${aws_instance.example.public_dns}"
}

Create and attach ebs storage

aws_ebs_volume and aws_instance ideally belong to the same availability_zone

resource "aws_volume_attachment" "ebs_att" {
  device_name = "/dev/sdh"
  volume_id   = "${aws_ebs_volume.example.id}"
  instance_id = "${aws_instance.web.id}"
}

resource "aws_instance" "web" {
  ami               = "ami-21f78e11"
  availability_zone = "us-west-2a"
  instance_type     = "t1.micro"

  tags = {
    Name = "HelloWorld"
  }
}

resource "aws_ebs_volume" "example" {
  availability_zone = "us-west-2a"
  size              = 1
}

Define storage from ec2 creation

variable "EC2_ROOT_VOLUME_SIZE" {
  type    = "string"
  default = "30"
  description = "The volume size for the root volume in GiB"
}
variable "EC2_ROOT_VOLUME_TYPE" {
  type    = "string"
  default = "gp2"
  description = "The type of data storage: standard, gp2, io1"
}
variable "EC2_ROOT_VOLUME_DELETE_ON_TERMINATION" {
  default = true
  description = "Delete the root volume on instance termination."
}

# then

resource "aws_instance" "example" {
  ami           = "${var.AMI_ID}"
  instance_type = "${var.EC2_INSTANCE_SIZE}"
  
  root_block_device {
    volume_size           = "${var.EC2_ROOT_VOLUME_SIZE}"
    volume_type           = "${var.EC2_ROOT_VOLUME_TYPE}"
    delete_on_termination = "${var.EC2_ROOT_VOLUME_DELETE_ON_TERMINATION}"
  }
}

Create a security group and use it afterwards (Allow income from 8080)

resource "aws_security_group" "http_group" {
    name = "terraform-example-instance"
    ingress {
        from_port = 8080
        to_port = 8080
        protocol = "tcp"
        cidr_blocks = ["0.0.0.0/0"]
    }
}

# add the property 
# vpc_security_group_ids = ["${aws_security_group.http_group.id}"] 
# in the aws_instance

Create a security group for ssh access (Experimental)

resource "aws_security_group" "ssh_group" {
    name = "terraform-example-instance"
    ingress {
        from_port = 22
        to_port = 22
        protocol = "tcp"
        cidr_blocks = ["0.0.0.0/0"]
    }
}

# add the property 
# vpc_security_group_ids = ["${aws_security_group.ssh_group.id}"] 
# in the aws_instance

Stoping/Starting instances with AWS CLI

aws ec2 stop-instances --region us-east-2 --instance-ids i-0123456789abcdef

aws ec2 start-instances --region us-east-2 --instance-ids i-0123456789abcdef

#If you need to fetch the instance ID quickly, you can define a TF output and get at it that way:
terraform output id
#    i-0123456789abcdef

References

• [Terraform up and running (local book)](/media/w/6529BB496A1EC696/Yevgeniy Brikman - Terraform Up and Running (Early Release)-O'Reilly Media (2017).pdf)

• https://learn.hashicorp.com/terraform/getting-started/build

• http://blog.shippable.com/setup-a-container-cluster-on-aws-with-terraform-part-2-provision-a-cluster

• https://towardsdatascience.com/seamlessly-integrated-deep-learning-environment-with-terraform-google-cloud-gitlab-and-docker-faee4b351e94