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

Bringing in high availability

With AWS, going HA can be as simple as putting instances into different subnets, assigned to different availability zones. An availability zone is an isolated location within one AWS region, and you can look at it as a separate data center.

We are passing subnet ID as a variable to the application module, and we are passing exactly one subnet ID. This needs to be changed, that is, we will update the subnet_id variable to be the list of two elements. Then, depending on the index of an aws_instance resource, we will assign either first or the second subnet to it.

First of all, replace the subnet_id variable with the subnets variable and specify type as list to avoid anything else to be passed to the module:

variable "subnets"   { type = "list "} 


If you set the default value of variable to be [], then Terraform will understand that this variable is a list.

In root template, we need to change the subnet_cidr variable to make it availability zone aware and...