This presentation covers techniques for building an AWS Lambda test harness application, allowing for local development and debugging of AWS Lambda functions.

1. Local Lambda Development and Debugging
Matt Billock
matt@backand.com

2. Agenda:
● AWS Lambda Overview
● Debugging AWS Lambda
● Building a local test harness
● Deployment with Backand CLI
● Quick overview of Backand

3. AWS Lambda
● Created in 2014, launched at
re:Invent
● Kicked off "serverless" (caveat)
● Function-as-a-Service
○Deploy code, not applications

4. Creating A Lambda Function
● Supports Node.JS, Python, C#, and
Java
○ Can call to server functionality (Linux)
● Code deployment options
○ Uploading as a ZIP file
○ Uploading from S3
○ Editing in in-browser editor

5. Creating A Lambda Function
Demo

6. Calling AWS Lambda Functions
● Event-based triggers
○ Also On-Demand
● Event Sources
○ AWS Services (S3, DynamoDB, others)
○ API Gateway
○ AWS SDK

7. Debugging Lambda Functions
● Cloudwatch Integration
○ Provides call record
● console.log()
○ Sends message to Cloudwatch
● … and that's it

8. Lambda Execution Environment
● Details kept proprietary by Amazon
● Based on Amazon Machine Instance
● Dynamically provisioned (hot vs cold)
● Temporary storage (/tmp, 500 MB)
○ NOT guaranteed to persist

9. Debugging Lambda Locally
● Need to mimic input format
● Need to mimic output format
○ Transformations in API Gateway
● Need a test harness

10. Creating a Test Harness
● Function Prototype
● Including Handler
● Mimicking Lambda Invocation
○ Parameters in event object
○ Handlers in the context object

11. Creating a Test Harness
● Calling a Lambda function, continued:
● Provide handlers in context argument

12. Test Harness Notes
● Callback mechanism provided by Lambda
○ Only supported by Node.JS actions
● Using callbacks in context parameter
○ Not officially supported
● Not a perfect substitute
○ Calls the function, but not from the same
environment

13. Improving Iteration Speed
● Per-line output
● Immediate feedback
● Breakpoints and other local
debugging tools
● Unit and Integration tests

14. Deploying Your Code
● Zip-file from S3, or manual upload
○ NOTE: zip only the source code,
not the parent folder!
● Testing upload
● Publishing
● Complex, non-intuitive

15. Using Backand's CLI Tool
● Backand On-Demand Node.JS
Lambda actions
● Backand CLI abstracts away
deployment
● npm install -g backand
● Requires registering with Backand

16. Deploying Lambda Code
● Initializing an action- backand action init
○ Arguments available in docs.backand.com
● Copy your Node.JS code into created
directory
● Deploy - backand action deploy
○ Arguments available in docs.backand.com

17. Calling Your Lambda
● Authentication
○ can be anonymous
○ api.backand.com/1/token
○ See docs
● cURL
curl -H "<auth header>" "https://api.backand.com/1/objects/action/<object>?name=<name>"
● JavaScript (with Backand SDK)
backand.object.action.get(...)

18. What is Backand?
● Serverless app platform
● Manages your app's database
● Manages your app's security and
authentication
● Provides custom server-side code execution
● Provides hosting options
● Provides logging, analytics, and more

19. Backand Features
● Automated REST API
● Bring your own Database
● Custom JavaScript Actions
● Server-Side Code Execution
● Batch and Bulk Processing
● Scheduled Tasks
● Automated messages
● Real-time Communications
● User and Role-based
Security
● Social Media Authentication
● GUI Schema Editor
● Custom Queries
● REST API Playground
● Sample Code Generation
● Hosting
● Detailed Analytics
● Logging
● Multi-Platform SDK
● Single Sign On Support

20. THANK YOU
https://github.com/backand
https://www.backand.com
matt@backand.com