AWS Lambda

Deep Dive


Hi there, I’m Sanjay 👋!

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About me

  • 🔭 Working: Cloud Developer working on Reactive Spring Boot, Kafka, Cassandra, Microservices, AWS.
  • 🖥️ Interests: I love building cool software and systems using Spring Boot, Kotlin and Go
  • 🌱 Learning: Go | Scala | Design Patterns
  • 💬 Ask me about: Java | Reactive Spring | AWS
  • 🧑‍🤝‍🧑 Collaboration: I'm looking to collaborate on several projects over here, please check out my GitHub repos

Languages, Frameworks and Platforms

Java Spring Kotlin Project Reactor Kafka Cassandra AWS Kubernetes

What is AWS Lambda Function

  • A Compute Service to run code without Provisioning or Managing Servers
  • Uses Containerization tech called Firecracker
  • Handles Server & OS Maintenance, Provisioning, Auto-Scaling, Logging
  • Code in one of the Languages supported by Lambda Runtimes

Lambda Concepts

  • Function: a resource invoked to run your code
  • Trigger: a resource/config that invokes a Lambda Function
  • Event: a JSON-formatted data for a Lambda Function to Process
  • Event Source Mapping: a resource that reads items from a Stream/Queue & invokes a function
  • Execution Env: provides a secure and isolated Runtime Environment for your Lambda function
  • Runtime: provides a lang-specific Environment that runs in an Execution Environment

What is Lambda Runtimes

  • Runtime provides a lang-specific env that runs in an execution env
  • It relays invocation Events, Context, & Responses between Lambda & the Function
  • Use AWS provided Lambda Runtimes or Build your own by implementing Runtime API

Execution Environment & Runtime

Lambda Execution Environment Lambda Execution Environment

Supported Lambda Runtimes

Node.js v18, v16, v14 & v12*
Python v3.9, v3.8, v3.7
Java v8, v11
C# .NET v5, v6 & .NET Core v3.1
Go v1.x
Ruby v2.7*
Custom Runtime - Based on Amazon Linux

Micronaut Custom Runtime Implementation Example

Lambda Function Java

public class MsgHandler implements RequestHandler<String, String> {
    public String handleRequest(String input, Context ctx) {
        context.getLogger().log("Input: " + input);
        return "Hello World - " + input;
public class StreamHandler implements RequestStreamHandler {
    public void handleRequest(InputStream is, OutputStream os, Context ctx) {
        String input = IOUtils.toString(is, "UTF-8");
        os.write(("Hello World - " + input).getBytes());
public class NoInterfaceHandler {
    public String customHandle(String input, Context context) {
        context.getLogger().log("Input: " + input);
        return "Hello World - " + input;


  • Automatically manages the underlying Compute Resources
  • Concurrency and Scaling controls
  • Pay Per Request Execution is millis
  • Multiple Event Sources: API-GW, SQS, S3, DynamoDB, etc.
  • Functions defined as Container Images
  • Lambda Extensions
  • Execute inside Private Subnets inside a VPC
  • File Systems Access + EFS


  • Memory: 128 MB to 10,240 MB
  • No Direct Way to assign CPU: 1,769 MB memory is equivalent of one vCPU
  • Function Timeouts: 15 minutes
  • Invocation Payload: 6 MB (sync) & 256 KB (async)
  • File descriptors: 1024
  • Execution processes/threads: 1024
  • No Async Processing Allowed: Lambda Instance Freezes once invocation is completed
  • 1 Lambda Instance serves only 1 request at time

Other Compute Options

Services Comparison with Lambda
AWS EC2 Not Serverless, More RAM/CPU/Storage, Always ON
AWS EKS Managed Container Platform on EC2
Fargate Serverless Container Platform on EC2
Beanstalk AWS Container based PaaS
GCP Cloud RUN Based on OSS Knative - Charged for Runtime only