How to test your Terraform code

24.JUN.2022

Senior DevOps Engineer

Rafael Natali

• 4+ years of experience with DevOps ecosystem (CI/CD, K8s, IaC, Cloud, open source)
• 15+ years overall IT experience
• HashiCorp Certified: Terraform Associate
• Google Professional Cloud DevOps Engineer
• 6x AWS Certified

​

rafael.natali@marionete.co.uk

https://github.com/rafaelmnatali

https://marionete.co.uk

2

© 2022 Marionete Limited

Why do you need to test your infrastructure?

Why “Terraform Plan” is not enough?

​

Introduction to “Terraform Test”

Testing your infrastructure - DEMO

“Terraform Test” limitations

1

2

3

4

5

© 2022 Marionete Limited

Test-driven infrastructure

Why do you need to test your infrastructure?

• Understand if code is doing what it’s supposed to. 
• Analyse configurations and dependencies before execution.
• Check if the infrastructure is configured correctly.
• Convert infrastructure requirements into test cases (TDD).

​

4

© 2022 Marionete Limited

Plan output

Why “Terraform Plan” is not enough?

• It does not verify if you have permission to execute the task.
• Dynamic content is only known after the apply

​

TERMINAL

• # module.gcs_bucket["eu"].google_storage_bucket.bucket will be created

+ resource "google_storage_bucket" "bucket" {

+ force_destroy = true

+ id = (known after apply)

+ location = "EU"

+ name = (known after apply)

...

5

© 2022 Marionete Limited

“Terraform Test”

Introduction to “Terraform Test”

• Experimental feature that allows us to write Terraform module tests in the Terraform language itself.
• Available since Terraform CLI v0.15.0
• It’s a separate command for more conveniently running multiple tests in a single action.
• Apply and Destroy testing model

​

6

© 2022 Marionete Limited

DEMO – GCP Buckets

Testing your infrastructure

• Bucket creation.
• Bucket creation in multiple locations.

7

© 2022 Marionete Limited

Experimental feature

“Terraform Test” limitations

There are a few limitations on how it works. The two main limitations I’d like to highlight are:

• Currently tests written in this way can only exercise the create and destroy behaviours.
• Capturing context about failures. “Terraform test” is limited in how much context it's able to gather about failures.

Please, refer to the Hashicorp documentation for a complete list.

​

8

© 2022 Marionete Limited