Updating and deleting stacks in AWS - Commands & Configuration

Introduction

Sometimes you need to change or remove your cloud resources after creating them. Updating stacks lets you change settings or add features. Deleting stacks removes all resources to keep things clean.

When you want to add a new server or database to your existing cloud setup

When you need to fix a mistake in your cloud resource configuration

When you want to remove all resources related to a project you finished

When you want to save money by deleting unused cloud resources

When you want to upgrade your application by changing its infrastructure

Config File - stack-template.yaml

stack-template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Description: Simple stack with an S3 bucket
Resources:
  MyBucket:
    Type: 'AWS::S3::Bucket'
    Properties:
      BucketName: example-stack-bucket-12345

This file defines a simple cloud stack with one S3 bucket named example-stack-bucket-12345. The Resources section lists what cloud resources to create. This template is used to create, update, or delete the stack.

Commands

This command creates a new stack named 'example-stack' using the template file. It sets up the resources defined in the template.

Terminal

aws cloudformation create-stack --stack-name example-stack --template-body file://stack-template.yaml

Expected Output

An error occurred (AlreadyExistsException) when calling the CreateStack operation: Stack [example-stack] already exists

→

--stack-name - Names the stack to create

→

--template-body - Specifies the template file to use

This command updates the existing stack 'example-stack' with any changes in the template file. Use this to change or add resources.

Terminal

aws cloudformation update-stack --stack-name example-stack --template-body file://stack-template.yaml

Expected Output

Waiting for stack update to complete...

Successfully updated stack example-stack

→

--stack-name - Specifies which stack to update

→

--template-body - Template file with updated resource definitions

This command deletes the stack named 'example-stack' and all its resources. Use this to clean up when you no longer need the stack.

Terminal

aws cloudformation delete-stack --stack-name example-stack

Expected Output

No output (command runs silently)

→

--stack-name - Specifies which stack to delete

This command checks the status of the stack 'example-stack' to confirm if it still exists or was deleted.

Terminal

aws cloudformation describe-stacks --stack-name example-stack

Expected Output

An error occurred (ValidationError) when calling the DescribeStacks operation: Stack with id example-stack does not exist

→

--stack-name - Specifies which stack to describe

Key Concept

If you remember nothing else from this pattern, remember: update stacks to change resources and delete stacks to remove them completely.

Common Mistakes

Trying to create a stack with a name that already exists

AWS CloudFormation does not allow duplicate stack names, so creation fails

Use update-stack to change an existing stack or delete the old stack before creating a new one

Not waiting for the update or delete operation to finish before running other commands

Commands may fail or show outdated information if the stack is still changing

Wait for the operation to complete or use wait commands to check status before proceeding

Deleting a stack without confirming you no longer need its resources

You lose all resources and data in the stack permanently

Double-check the stack contents and backup any important data before deleting

Summary

Use 'aws cloudformation update-stack' to change resources in an existing stack.

Use 'aws cloudformation delete-stack' to remove all resources and the stack itself.

Check stack status with 'aws cloudformation describe-stacks' to confirm changes or deletion.

Practice

1. What is the primary purpose of the update-stack command in AWS CloudFormation?

easy

A. To create a new stack from a template

B. To safely change existing cloud resources managed by a stack

C. To delete all resources created by a stack

D. To list all stacks in your AWS account

Solution

1. Step 1: Understand the role of update-stack

   The update-stack command is used to modify resources that are already managed by an existing CloudFormation stack.

2. Step 2: Differentiate from other commands

   Unlike delete-stack which removes resources, update-stack changes them safely without deleting the stack.

3. Final Answer:

   To safely change existing cloud resources managed by a stack -> Option B

4. Quick Check:

   update-stack = change resources safely [OK]

Hint: Update-stack changes resources; delete-stack removes them [OK]

Common Mistakes:

• Confusing update-stack with delete-stack
• Thinking update-stack creates new stacks
• Assuming update-stack lists stacks

2. Which AWS CLI command syntax correctly deletes a stack named MyAppStack?

easy

A. aws cloudformation delete-stack --stack-name MyAppStack

B. aws cloudformation update-stack --stack-name MyAppStack

C. aws cloudformation remove-stack --name MyAppStack

D. aws cloudformation destroy-stack --stack MyAppStack

Solution

1. Step 1: Identify the correct delete command

   The correct AWS CLI command to delete a stack is delete-stack with the parameter --stack-name.

2. Step 2: Verify syntax correctness

   aws cloudformation delete-stack --stack-name MyAppStack uses the exact syntax: aws cloudformation delete-stack --stack-name MyAppStack, which is valid and deployable.

3. Final Answer:

   aws cloudformation delete-stack --stack-name MyAppStack -> Option A

4. Quick Check:

   delete-stack + --stack-name = correct syntax [OK]

Hint: Delete stacks with 'delete-stack' and '--stack-name' [OK]

Common Mistakes:

• Using update-stack instead of delete-stack
• Wrong parameter names like --name or --stack
• Using non-existent commands like remove-stack or destroy-stack

3. Given this AWS CLI command sequence:

aws cloudformation update-stack --stack-name TestStack --template-body file://template.json
aws cloudformation describe-stacks --stack-name TestStack

What is the expected behavior after running these commands?

medium

A. The stack TestStack is updated with the new template, and its status is shown

B. The stack TestStack is deleted, and no status is returned

C. A new stack named TestStack is created, and its details are displayed

D. The command fails because update-stack cannot be followed by describe-stacks

Solution

1. Step 1: Understand update-stack effect

   The update-stack command modifies the existing stack named TestStack using the provided template.

2. Step 2: Describe-stacks shows current stack status

   The describe-stacks command retrieves details about TestStack, including its updated status.

3. Final Answer:

   The stack TestStack is updated with the new template, and its status is shown -> Option A

4. Quick Check:

   update-stack changes stack + describe-stacks shows status [OK]

Hint: Update then describe shows updated stack status [OK]

Common Mistakes:

• Thinking update-stack deletes the stack
• Assuming describe-stacks creates a new stack
• Believing update-stack and describe-stacks cannot be used sequentially

4. You run aws cloudformation update-stack --stack-name ProdStack --template-body file://newtemplate.json but get an error saying the stack is in UPDATE_IN_PROGRESS state. What should you do to fix this?

medium

A. Ignore the error and rerun update-stack multiple times

B. Run delete-stack immediately to remove the stack

C. Change the stack name and try update-stack again

D. Wait for the current update to finish before running update-stack again

Solution

1. Step 1: Understand stack states during update

   When a stack is in UPDATE_IN_PROGRESS, it means an update is already running and must complete before another update starts.

2. Step 2: Choose the correct action

   Waiting for the current update to finish avoids conflicts and errors. Deleting or renaming the stack is unnecessary and may cause data loss or confusion.

3. Final Answer:

   Wait for the current update to finish before running update-stack again -> Option D

4. Quick Check:

   UPDATE_IN_PROGRESS means wait before next update [OK]

Hint: Wait for update to finish before next update [OK]

Common Mistakes:

• Trying to delete stack during update
• Renaming stack instead of waiting
• Ignoring error and retrying immediately

5. You want to update a stack but also ensure that if the update fails, the stack rolls back to its previous state automatically. Which AWS CloudFormation option should you avoid using with update-stack to achieve this?

hard

A. --rollback-configuration

B. --no-rollback

C. --disable-rollback

D. --enable-rollback

Solution

1. Step 1: Understand rollback behavior in update-stack

   By default, CloudFormation rolls back stack updates on failure. The --disable-rollback option disables this behavior.

2. Step 2: Identify the correct option to keep rollback enabled

   To ensure rollback happens automatically on failure, you should NOT disable rollback. Therefore, do not use --disable-rollback. The default behavior is rollback enabled, so omit this option or explicitly avoid disabling rollback.

3. Step 3: Analyze options

   --rollback-configuration is for configuring alarms, --enable-rollback and --no-rollback are not valid AWS CLI options.

4. Final Answer:

   --disable-rollback disables rollback; omit it to keep rollback enabled -> Option C

5. Quick Check:

   Omit --disable-rollback to keep rollback on failure [OK]

Hint: Do not use --disable-rollback to keep rollback active [OK]

Common Mistakes:

• Using non-existent --enable-rollback option
• Confusing disable-rollback disables rollback
• Assuming rollback is off by default