AWS SAM CLI Commands and Use Cases: Complete 2025 Guide
The AWS SAM CLI is the essential toolkit for serverless developers. With 20+ commands for local testing, debugging, and deployment, mastering SAM CLI can accelerate your development workflow by 40%. This guide covers all essential commands with real-world use cases.
Why SAM CLI Matters for Serverless Development
SAM CLI bridges the gap between local development and cloud deployment. Key benefits:
Local Lambda Testing
Test functions offline without cloud deployment cycles
Rapid Iteration
Hot-reloading for immediate code feedback
CI/CD Integration
Scriptable commands for deployment pipelines
Debugging Superpowers
VS Code/IDE integration for breakpoints
Kid-Friendly Analogy
Think of SAM CLI like a flight simulator for pilots. Instead of flying a real plane (deploying to AWS), you can practice maneuvers (test code) safely on the ground (your laptop) before takeoff.
Essential SAM CLI Commands and Use Cases
SAM CLI Development Workflow
1. sam init – Project Bootstrap
Command: sam init
Use Case: Start new projects using pre-built templates
$ sam init
# Quickstart with Node.js template
$ sam init –name my-app –runtime nodejs18.x –app-template hello-world
Real-World Scenario:
Creating a new REST API backend with Python:
–name product-api
–runtime python3.11
–app-template quick-start-web
2. sam build – Dependency Management
Command: sam build
Use Case: Resolve dependencies and build artifacts
$ sam build
# Build with cached dependencies
$ sam build –cached
Real-World Scenario:
Building a Lambda layer with native extensions:
–use-container
–container-env-var “GIT_TOKEN=my_token”
3. sam local invoke – Function Testing
Command: sam local invoke
Use Case: Test individual Lambda functions locally
$ sam local invoke MyFunction -e event.json
# Stream logs during invocation
$ sam local invoke -d 5858 –log-file ./debug.log
Real-World Scenario:
Testing an image processing function:
-e s3-event.json
–env-vars env.json
4. sam local start-api – API Simulation
Command: sam local start-api
Use Case: Emulate API Gateway locally
$ sam local start-api -p 8080
# Hot-reloading for rapid development
$ sam local start-api –warm-containers LAZY
Kid-Friendly Explanation
sam local start-api is like building a miniature version of your entire app on your desk. You can test all buttons (API endpoints) without turning on the real machine (deploying to AWS).
5. sam deploy – Cloud Deployment
Command: sam deploy
Use Case: Deploy applications to AWS
$ sam deploy –guided
# CI/CD friendly deployment
$ sam deploy
–stack-name prod-stack
–s3-bucket my-deployment-bucket
–capabilities CAPABILITY_IAM
Real-World Scenario:
Production deployment with approval prompts:
–stack-name production
–config-env prod
–confirm-changeset
–disable-rollback
Advanced Debugging Techniques
VS Code Debugging Setup
{
“configurations”: [
{
“name”: “Attach to SAM CLI”,
“type”: “node”,
“request”: “attach”,
 ”address”: “localhost”,
“port”: 5858,
“localRoot”: “${workspaceRoot}”,
“remoteRoot”: “/var/task”
}
]
}
sam local invoke –debug
Command: sam local invoke --debug
Use Case: Debug Lambda functions with IDE breakpoints
$ sam local invoke –debug-port 5858 MyFunction
# Debug Node.js with Chrome DevTools
$ sam local invoke –debugger-path node_modules
CI/CD Integration Patterns
GitHub Actions
run: |
sam build
sam deploy –no-confirm-changeset
CodePipeline
build:
commands:
– sam build
deploy:
commands:
– sam deploy –no-confirm-changeset
Troubleshooting Common SAM CLI Issues
- Dependency errors: Use
--use-containerflag for consistent builds - Timeout errors: Increase
--container-hostand--container-host-interfacevalues - Permission issues: Run with
--debugto trace IAM policies - Cold start delays: Use
--warm-containers EAGERduring development
Kid-Friendly Tip
When SAM CLI acts up, sam --info is like asking “How are you feeling?” to your computer. It tells you exactly what’s working and what’s not!
Best Practices for 2025
- Use
sam syncfor rapid development iterations - Implement
sam pipelinefor CI/CD automation - Leverage
sam logs -tfor real-time debugging - Enable
--cachedbuilds for faster deployments - Integrate
sam validatein pre-commit hooks
Further Learning on Serverless Servants
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