Book Image

Getting Started with Terraform - Second Edition

By : Kirill Shirinkin
1 (1)
Book Image

Getting Started with Terraform - Second Edition

1 (1)
By: Kirill Shirinkin

Overview of this book

Terraform is a tool used to efficiently build, configure, and improve the production infrastructure. It can manage the 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 the complete management of infrastructure with Terraform, starting with the basics of using providers and resources. It 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. The book ends with the complete workflow of managing a production infrastructure as code—this is achieved with the help of version control and continuous integration. The readers will also learn how to combine multiple providers in a single template and manage different code bases with many complex modules. It focuses on how to set up continuous integration for the infrastructure code. The readers will be able to use Terraform to build, change, and combine infrastructure safely and efficiently.
Table of Contents (15 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Retrieving module data with outputs

Another useful construct that Terraform provides are outputs. In an output, you define which data you want to be returned by the module. Add the following line to the very bottom of the ./modules/application/ file:

output "hostname" { 
  value = "${}" 

Now you can use this output inside the like this:

module "crazy_foods" { 
  source = "./modules/application" 
  vpc_id = "${}" 
  subnet_id = "${}" 
  name = "CrazyFoods ${module.mighty_trousers.hostname}" 

Besides the obvious ability to get data from the module, there is another use case for module outputs: forcing dependencies. Here is the graph before passing the output to the second module:

Here is the graph with dependency forced:

That's a completely different level of graph-beauty, I hope you agree. But sometimes, as we discussed previously, we have to do it. For example, one module creates a master server...