20 CloudFormation Template Interview Questions and Answers

CloudFormation is a popular tool for provisioning and managing cloud infrastructure. It is used by many organizations to automate the process of setting up and maintaining cloud resources. When interviewing for a position that involves CloudFormation, you can expect to be asked questions about your experience and knowledge of the tool. In this article, we will review some of the most common CloudFormation interview questions and how you should answer them.

CloudFormation Template Interview Questions and Answers

Here are 20 commonly asked CloudFormation Template interview questions and answers to prepare you for your interview:

1. What is CloudFormation?

CloudFormation is a tool from Amazon Web Services that allows you to create templates for describing and provisioning AWS resources. With CloudFormation, you can define your AWS infrastructure in a template file, and then use that template to create and provision AWS resources automatically.

2. Can you explain what a template is in the context of AWS CloudFormation?

A template is a blueprint or set of instructions for creating a stack in AWS CloudFormation. A template can be used to create a new stack or update an existing stack. A template can include parameters, mappings, conditions, outputs, and resources.

3. What are stacks?

A stack is a collection of resources that are created and managed as a unit by CloudFormation. A stack can contain any number of resources, and you can create as many stacks as you like.

4. How do you create a stack using CloudFormation?

You can create a stack using CloudFormation by creating a template that defines all of the resources and parameters that you want to include in your stack, and then using the AWS Management Console, AWS Command Line Interface, or AWS SDKs to upload the template and create the stack.

5. How can you delete a stack that’s already running on AWS CloudFormation?

You can delete a stack that’s already running on AWS CloudFormation by using the AWS CloudFormation console, the AWS CloudFormation API, or the AWS CloudFormation CLI.

6. What types of resources does AWS CloudFormation support?

AWS CloudFormation supports a wide range of resources, including Amazon EC2 instances, Amazon S3 buckets, Amazon DynamoDB tables, and more.

7. How would you use AWS CloudFormation to configure an EC2 instance in a VPC environment?

You would use the AWS::EC2::Instance resource type in your CloudFormation template. You would also need to specify the VPC and subnet in which you want to launch the instance. You can find more information about configuring an EC2 instance in a VPC environment in the AWS CloudFormation User Guide.

8. Is it possible to run nested stacks using AWS CloudFormation? If yes, then how?

Yes, it is possible to run nested stacks using AWS CloudFormation. You can do this by creating a parent stack that contains a reference to the child stack template. The child stack template can then be used to launch the nested stack.

9. What are some ways to update or edit a running stack without terminating it?

One way to update a running stack is to use the UpdateStack API call. This will allow you to update the template and/or parameters for an existing stack. Another way to update a running stack is to use the CloudFormation console. From the console, you can select the stack you want to update, make your changes, and then select “Update Stack”.

10. How do you define parameters while launching a stack using AWS CloudFormation?

You can specify parameters while launching a stack using AWS CloudFormation by adding the “Parameters” section to your template. In this section, you can specify the parameter name, type, and default value. You can also specify whether the parameter is required or not.

11. What are the different types of templates supported by AWS CloudFormation?

AWS CloudFormation supports three different types of templates: JSON, YAML, and HOT. JSON is the most common and most basic type of template. YAML is a superset of JSON, so it can be used to create more complex templates. HOT is a template format that is specifically designed to be used with the Heat tool, which is used to orchestrate the creation of cloud infrastructure.

12. What are pseudo-parameters and how are they used with AWS CloudFormation?

Pseudo-parameters are variables that are set by AWS CloudFormation and are available to all resources in a stack. These variables can be used to reference information about the stack or the AWS environment, and can be used in conjunction with other resources to create dynamic templates.

13. Is it possible to launch non-AWS resources using AWS CloudFormation? If yes, then how?

Yes, it is possible to launch non-AWS resources using AWS CloudFormation. You can do this by creating a custom resource in your CloudFormation template. This custom resource can be used to launch any type of resource, including those that are not hosted on AWS.

14. What are the limitations of AWS CloudFormation?

AWS CloudFormation has a few limitations that you should be aware of before using it to manage your AWS resources. One such limitation is that CloudFormation can only manage resources within a single region. Additionally, CloudFormation templates must be valid JSON or YAML, which can sometimes be tricky to work with. Finally, CloudFormation stacks can only be created or updated one at a time, so you need to plan accordingly if you want to update multiple stacks at once.

15. What is Change Set? Why is it important when working with AWS CloudFormation?

A change set is a summary of changes that will be made to a stack if you execute the change set. It is important when working with AWS CloudFormation because it allows you to see what changes will be made to your stack before you actually make those changes. This way, you can avoid any potential problems that might occur if the changes are made without first being reviewed.

16. Is there any difference between “Update Stack” and “Create Stack” in AWS CloudFormation? If yes, then what?

Yes, there is a difference between “Update Stack” and “Create Stack” in AWS CloudFormation. “Update Stack” will only update the resources that have changed since the last time the stack was updated, whereas “Create Stack” will create a new stack with all of the resources defined in the template.

17. Can you give me some examples of real world applications built using AWS CloudFormation?

Some examples of real world applications built using AWS CloudFormation include:

– A social media platform
– A gaming platform
– A video streaming platform
– A web hosting platform

18. What are custom resources and why do we need them when working with AWS CloudFormation?

Custom resources are pieces of code that can be used within an AWS CloudFormation template to perform tasks that are not natively supported by CloudFormation. This could be something like calling an external API, or performing some sort of custom logic. Custom resources can be written in any language, and are executed by AWS Lambda.

19. What is drift detection and how does it work with AWS CloudFormation?

Drift detection is a feature of AWS CloudFormation that allows you to detect whether your AWS CloudFormation stack has drifted from its original configuration. This can happen if someone manually updates a resource outside of AWS CloudFormation, or if an AWS CloudFormation template is updated without also updating the stack. Drift detection will compare the current state of your stack with the template that was used to create the stack, and will report any differences that it finds.

20. Can you explain the different stages involved in deploying a new application version using AWS CloudFormation?

When you are ready to deploy a new version of your application using AWS CloudFormation, there are a few different stages that you will need to go through. First, you will need to update your CloudFormation template to reflect the changes that you have made to your application. Next, you will need to create a new stack using this updated template. Finally, you will need to update your application to point to the new stack.