CloudFormation Stacks and Stack Operations

A CloudFormation stack is a collection of AWS resources that are created, updated, and deleted as a single unit. When you submit a template to CloudFormation, it creates a stack that tracks every resource defined in that template. Understanding how to manage stacks — creating, updating, monitoring, and deleting them — is essential for working with CloudFormation in practice.

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What is a Stack?

A stack is the fundamental deployment unit in CloudFormation. It has:

• A name — a unique identifier within a region and account
• A template — the YAML or JSON file that defines the resources
• A status — indicates whether the stack is being created, updated, or has completed
• A collection of resources — the actual AWS resources managed by the stack
• A history of events — a log of every action CloudFormation has taken

Think of a stack as a single "unit of infrastructure" — all the resources in a stack are meant to work together.

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Stack Statuses

CloudFormation tracks the lifecycle of each stack through a series of statuses:

Status	Meaning
CREATE_IN_PROGRESS	Resources are being created
CREATE_COMPLETE	All resources were created successfully
CREATE_FAILED	One or more resources failed to create
UPDATE_IN_PROGRESS	An update is being applied
UPDATE_COMPLETE	The update succeeded
UPDATE_ROLLBACK_IN_PROGRESS	The update failed and is being rolled back
UPDATE_ROLLBACK_COMPLETE	The rollback after a failed update is complete
DELETE_IN_PROGRESS	Resources are being deleted
DELETE_COMPLETE	All resources have been deleted
ROLLBACK_IN_PROGRESS	Initial creation failed and resources are being cleaned up
ROLLBACK_COMPLETE	Rollback after failed creation is complete

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Creating a Stack

Via the CLI

aws cloudformation create-stack \
  --stack-name my-app-stack \
  --template-body file://template.yaml \
  --parameters ParameterKey=Environment,ParameterValue=production \
               ParameterKey=DBPassword,ParameterValue=MySecurePass123

Via the Console

1. Open the CloudFormation console
2. Click Create stack
3. Upload your template or specify an S3 URL
4. Enter the stack name and parameter values
5. Configure stack options (tags, IAM role, rollback settings)
6. Review and click Create stack

Using an S3 Template

For templates larger than 51,200 bytes, you must upload to S3 first:

aws s3 cp template.yaml s3://my-templates-bucket/template.yaml

aws cloudformation create-stack \
  --stack-name my-app-stack \
  --template-url https://my-templates-bucket.s3.amazonaws.com/template.yaml

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Monitoring Stack Events

Every action CloudFormation takes is recorded as a stack event. You can monitor events to track progress and debug failures:

aws cloudformation describe-stack-events \
  --stack-name my-app-stack

Events include:

• The resource type being created or updated
• The logical resource ID from your template
• The physical resource ID assigned by AWS
• The status of that resource
• A reason if the operation failed

Waiting for Completion

The CLI can block until a stack operation completes:

aws cloudformation wait stack-create-complete \
  --stack-name my-app-stack

echo "Stack creation complete!"

This is useful in CI/CD pipelines where you need to wait before proceeding.

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Updating a Stack

To update a running stack, modify your template and submit an update: