Top Terraform Interview Questions and Answers

Terraform is an open-source infrastructure as code or IaC tool created by HashiCorp. Terraform helps us build, change, and version cloud and on-prem resources efficiently and safely. We then have a consistent workflow to provision and manage our infrastructure throughout its lifecycle. This blog focuses on Terraform interview questions to help you get ready for your interview.

Terraform Interview Questions and Answers

Here are some Terraform interview questions and answers to give you an idea of what to expect:

1. What are the steps of Terraform’s core workflow?

The core workflow of Terraform has three steps. The first is to write and includes creating infrastructure in code. The second is to plan and involves planning ahead of time to check how the changes may look before implementing them. Lastly, the third is to apply, which deals with creating a repeatable infrastructure.

2. How would you prevent Error Duplicate Resource?

Based on the needs and the situation, we can prevent Error Duplicate Resource in three ways. You can remove the duplicate resource from the configuration or manually delete it from the infrastructure. Otherwise, you could use the Terraform import command to import the existing resource into your state file, and Terraform will manage it without duplication. Alternatively, we can discard the resource from the APIs.

3. What do you know about the “.terraform" directory?

A .terraform directory is the result of running terraform init on a Terraform project. It serves as the local cache for several important components of Terraform. 

Terraform needs these cached resources to work its way around managing and provisioning infrastructure without having to re-download so many dependencies. It is worth noting that the .terraform directory should not be under any version control system, such as Git. It can contain environment-specific data that is different between deployments.

4. What are some of the version control tools that Terraform supports?

Terraform easily integrates with a number of Version Control Systems that allow teams to manage changes through code reviews and collaboration. Currently, the list of supported VCS platforms includes but is not limited to GitHub, GitLab CE/EE, Bitbucket Cloud, and Azure DevOps.

Such integrations enable the use of features like automated pipelines applying Terraform configurations to track changes and maintain history. This way, Terraform Cloud or Terraform Enterprise could be configured to collaborate with VCS repositories in order to automatically make changes to the infrastructure during a pull request or merge.

5. Define Modules in Terraform

A module in Terraform is a container for numerous resources that come in usage together. At the most basic level, every Terraform configuration could be considered a module. Modules in Terraform allow for code reusability, organization, and abstraction. 

Your infrastructure should be fragmented into smaller, more self-contained modules. This helps you eliminate redundancy, ensure consistency, and manage the growing complexity. 

A typical example would be to create a module responsible for managing a VPC that can then be reused across any number of other environments. You could source the modules from the Terraform Registry or local paths or version control, allowing for scalable infrastructure. 

Terraform Interview Questions For Practice

Here are some basic Terraform interview questions to get you started:

1. Talk about Terraform and how it works.

2. Describe some key features of Terraform.

3. Name some use cases of Terraform.

4. Why opt for Terraform for DevOps?

5. Describe some key features of Terraform.

6. What is IaC?

7. How does Terraform core work?

8. Define and describe the usage of Terraform init.

9. What is the use of a Terraform provider?

10. Talk about some basic CLI commands.

11. Define and describe Terraform D.

12. What is Terraform's backend, and what does it do?

13. What does cloud agostic mean, and is Terraform cloud agostic?

14. Can we have multi-provider deployments in Terraform?

15. Name some built-in provisioners in Terraform and describe their usage.

Advanced Terraform Interview Questions for Experienced Developers

Next, check out these advanced Terraform interview questions to gauge your preparation level.

1. What’s the process for recovering from a failed apply command in Terraform?

2. Describe State File Locking.

3. What is Terragrunt, and what is its usage?

4. What is a Remote Backend in Terraform?

5. What is Terraform CLI, and what are its uses?

6. What is Terraform HCL, and what are its uses?

7. What are the use cases for Terragrunt?

8. What’s the process to make an object of one module available to another module at a high level?

9. What is a Tainted Resource?

10. How can we ignore duplicate resource errors when using Terraform apply?

11. What are the guidelines to follow when using Terraform modules?

12. How do we utilize callbacks on Azure by using Terraform?

13. Desribe the Terraform request flow architecture.

14. Can we have callbacks with Terraform on Azure?

15. What’s Terraform cloud, and what are its uses?

Terraform Technical Interview Questions

Lastly, make sure you can answer these technical interview questions before your Terraform interview:

1. Can we add policies to any open-source or pro version of Terraform?

2. How can we lock Terraform module versions?

3. What’s the difference between Terraform and Cloudformation?

4. What’s a null resource in Terraform?

5. What’s the difference between Terraform and Ansible?

6. What does the Terraform -version command do?

7. What does the Terraform fmt command do?

8. What does the Terraform providers command do?

9. What does the Terraform validate command do?

10. What does the Terraform destroy command do?

11. What does the Terraform init command do?

12. What does the Terraform apply command do?

13. What does the Terraform graph command do?

14. What does the Terraform plan command do?

15. What does the Terraform refresh command do?

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FAQs: Terraform Interview Questions

Q1. What does Terraform do?

Terraform creates an implementation plan and defines what it will need to do to attain the preferred state. It then executes the plan to construct the described infrastructure. Terraform checks what changed with configuration changes and generates practical and incremental execution plans.

Q2. Is it possible to have callbacks with Terraform on Azure?

Yes, we can have callbacks on Azure with Terraform with the help of the Azure Event Hubs.

Q3. Can we use Terraform for on-prem infrastructure?

Yes, we can utilize Terraform for on-prem infrastructure, and there are providers available to choose from.

Q4. How can we check the version of Terraform that’s running?

We can use the command terraform -version to get the version of Terraform that’s running.

Q5. What are some key competitors of Terraform?

Ansible, Kubernetes, Packer, and Cloud Foundry are some key competitors of Terraform.

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