Book Image

Getting Started with Terraform

By : Kirill Shirinkin
Book Image

Getting Started with Terraform

By: Kirill Shirinkin

Overview of this book

Terraform is a tool used to efficiently build, configure, and improve production infrastructure. It can manage existing infrastructure as well as create custom in-house solutions. This book shows you when and how to implement infrastructure as a code practices with Terraform. It covers everything necessary to set up complete management of infrastructure with Terraform, starting with the basics of using providers and resources. This book is a comprehensive guide that begins with very small infrastructure templates and takes you all the way to managing complex systems, all using concrete examples that evolve over the course of the book. It finishes with the complete workflow of managing a production infrastructure as code – this is achieved with the help of version control and continuous integration. At the end of this book, you will be familiar with advanced techniques such as multi-provider support and multiple remote modules.
Table of Contents (15 chapters)
Getting Started with Terraform
About the Author
About the Reviewer
Customer Feedback

Handling resource updates

Let's change our instance's name to be hello-updated-instance:

resource "aws_instance" "hello-instance" {
  ami = "ami-9bf712f4"
  instance_type = "t2.micro"
  subnet_id = "subnet-5f22f536"
  tags {
    Name = "hello-update-instance"

Before we actually run the update, wouldn't it be useful to see what exactly Terraform would do when we run the terraform apply command again? Luckily, there is the terraform plan command that does exactly the same, that is, it shows you what applying would do by checking the template, state file, and actual state of the resource:

$> terraform plan
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but
will not be persisted to local or remote state storage.
aws_instance.hello-instance: Refreshing state... (ID: i-119a10ac)
The Terraform execution plan has been generated and is shown below.
Resources are shown in alphabetical order for quick scanning. Green resources...