AWS SAM and CDK for serverless and IaC

Automating Deployments on AWS

Dunieski Otano

Amazon Web Services Solutions Architect

A 2,000-line YAML file

• One Lambda + API Gateway grew into 2,000 lines of YAML
• Every IAM role, log group, and permission spelled out
• A typo lands halfway down a permission policy
• SAM and CDK collapse this into a few lines

AWS SAM at a glance

• SAM is a CloudFormation extension for serverless
• Concise resource types: AWS::Serverless::Function, ::Api
• The SAM CLI builds, packages, and deploys
• Templates transform into plain CloudFormation

The SAM workflow

• sam init: scaffold a project from a template
• sam validate: check the template before building
• sam build: compile and package the code
• sam deploy: ship to a CloudFormation stack

AWS CDK at a glance

• Write infrastructure in TypeScript, JavaScript, Python, Java, C#, Go
• Compile to CloudFormation with cdk synth
• Deploy with cdk deploy; rebuilds on every code change
• Same stack and resource concepts as CloudFormation

CDK construct levels

• L1: a 1-to-1 wrap of a CloudFormation resource
• L2: curated constructs with sensible defaults
• L3: patterns that bundle multiple resources
• Higher levels = fewer lines, less control

When to use each

• Raw CloudFormation: full control, ops-friendly
• SAM: pure serverless apps, fastest path
• CDK: complex infra, programming-language teams
• All three deploy the same way underneath

All three deploy as CloudFormation

• SAM transforms to CloudFormation
• CDK synths to CloudFormation
• The resulting stack uses the same events, drift, change sets
• Rollbacks work the same regardless of toolkit

Let's practice!

Automating Deployments on AWS