AWS Lambdas

Introduction

Purpose

Open questions

• How to handle webhooks, e.g. gitlab webhook on local ubuntu
• how to test lambda code on local ubuntu machine?
  • AWS Lambda Runtime Interface Emulator (RIE)
  • Moto (for AWS service mocking)
  • LocalStack (Full AWS Simulation)

Reference

• Understanding AWS Lambda’s invoke throttling limits
• AWS Lambda FAQs

TODO

• how to deploy lambdas
• what languages are supported by lambdas

Overview

• Supported language
  • C#
  • Go
  • Java
  • Node.js
  • PowerShell
  • Python
  • Ruby
  • Rust

Writing lambdas

• Define Lambda function handler in Node.js

JS Lambda script

• handler(event, context) - the entry function

  • event - a JSON formatted document that contains data for your function to process.
  • context - contains information about the function invocation and execution environment.

• TODO Clean-up https://docs.aws.amazon.com/lambda/latest/dg/getting-started.html#gettingstarted-cleanup

Layers

• TODO look into layers Creating a .zip deployment package with dependencies
• TODO Creating and deleting layers in Lambda
• TODO Adding layers to functions
• TODO Managing Lambda dependencies with layers
• TODO Using AWS SAM with layers

Creating a project

• ?
• cd my_function
• ?
• npm install aws-xray-sdk ?
• Create a directory under node_modules with the name of your module and save your custom written packages there.
• zip -r ../my_deployment_package.zip .

Deploying Lambdas

Deploying lambdas manually

• Create your first Lambda function

• Deploy Node.js Lambda functions with .zip file archives

• .zip

  • index.mjs

Deploying lambdas using serverless

• Serverless Framework - An Introduction

• osls

• Official Serverless Framework docs — The getting started guide at serverless.com/framework/docs is well-structured and assumes AWS familiarity.

  • It walks through creating, deploying, and managing Lambda functions with CloudFormation under the hood, which is great for understanding how the two connect.

• AWS's own Lambda documentation — Before diving deep into Serverless Framework abstractions, it helps to understand the raw Lambda execution model, cold starts, and IAM role requirements.

  • The AWS Lambda Developer Guide covers this well.

• "Serverless Stack" (sst.dev) — This is a free, comprehensive tutorial that builds a full-stack app step by step. It's particularly good because it explains the CloudFormation concepts as they come up rather than assuming you already know them.

• Yan Cui's "Production-Ready Serverless" course — Yan is one of the most respected voices in the serverless space.

  • His course goes beyond basics into real-world patterns like structured logging, error handling, and performance optimization — things a senior engineer will want to know quickly.

• "Serverless Architectures on AWS" by Peter Sbarski — A good book for someone who already thinks in infrastructure terms but needs to shift their mental model toward event-driven, function-as-a-service patterns.[3:55 PM]I completely agree with Claude's conclusion

• For someone with strong AWS experience, I'd suggest starting with the official Serverless Framework docs alongside the Lambda developer guide, then moving to the SST tutorial for hands-on practice.

  • The framework essentially generates CloudFormation templates, so as he works through examples, the CloudFormation side will start clicking naturally.

Logs

AWS Console - Cloudwatch logs

Find the logs Directly in Cloudwatch

• Navigate to: AWS Console -> CloudWatch -> Logs -> Log groups
• Find the log group
  • Search for: /aws/lambda/pre-production-engineEntityListAlpha
  • Or filter by: /aws/lambda/pre-production-
• View logs
  • Click on the log group
  • Click on any log stream to see the actual logs
  • Log streams are organized by date/time
  • Alternative: From Lambda Console
  • Go to Lambda

Find the logs via the lambda entry

• AWS Console -> Lambda -> Functions
• Find the function
  • Search for: pre-production-engineEntityListAlpha
• View logs
  • Click on the function
  • Go to the Monitor tab
  • Click View CloudWatch logs button
  • Or click View logs in CloudWatch from the dropdown

Get the logs via aws cli

• List recent log streams

• aws logs describe-log-streams --log-group-name /aws/lambda/pre-production-engineEntityListAlpha --order-by LastEventTime --descending --max-items 10

• or Get the latest logs (last 10 minutes)

  • aws logs tail /aws/lambda/pre-production-engineEntityListAlpha --since 10m --follow

  Recipes

List all lambdas with a specific env var

• aws lambda list-functions --query "Functions[?Environment.Variables.S3_STATIC_TENANT_ROLE != null].FunctionName" --output text | tr '\t' '\n' | grep -v '^$' | sort