[AWS] Serverless

“Serverless” is an architecture where an entire infrastructure is managed by a cloud provider, and the resources are dynamically allocated on demand. A cloud provider handles the infrastructure management tasks (such as capacity provision, patching, auto-scaling, and high availability) so that you can focus on writing code.

Serverless Features

• No servers (host machines) to manage
• Inherent scaling and high availability (HA)
• Pay-as-you-go model
  • No charge in idle time
• Quick deployment
• For event-driven architecture or/and microservice-based architecture

Backend as a Service (BaaS)

BaaS is a cloud service model where cloud providers host the server-side logic. A client application running via a web browser or mobile interface connects to the cloud server through APIs.

• BaaS is popularized by the explosion of mobile applications.
• BaaS provides common functionalities such as authentication, database management, and data storage.
• You do not need to code. You just use functionalities through APIs.

Function as a Service (FaaS)

A function is a cloud service where business logic is processed by event-triggered containers that are ephemeral in nature.

• Unlike BaaS, you provide your own code that is executed in a cloud.
• Event-triggered: The code is executed by triggers that you define.
• Containers: Once an event is triggered, a code in a container runs your code.
• Dynamic Scaling: You do not need to create instances of your application. The cloud provider takes care of creating and destroying containers.
• Ephemeral: Your application only runs when it is needed.

APIs

• API Proxy: An HTTP server that allows decoupling from backend services by routing calls to specific endpoints
• API Gateway: An API proxy, which provides additional features such as authentication, input validation, monitoring, and advanced routing.

Serverless Architecture

• You do not even need to configure and manage infrastructures such as VPC, routing, or servers.
• You do not need to create or destroy instances of your application manually.
• BaaS and FaaS can be a part of the serverless architecture.
• Serverless does not fit all types of applications. It is not a magic sword.
  • Best for short-running tasks that can be charged for the running time

Advantages

• Speed to Market: By eliminating the infrastructure management overhead, you can release your applications quickly.
• Scalable: You can scale your application based on demands automatically.
• Lower Cost: Serverless applications are event-driven, and you are charged only when your code is executed.

Drawbacks

• Easy to become vendor (cloud-provider) locked
• Data security concern
• No ability for infrastructure optimization
• Testing and debugging are not easy
• Usually not built for long-running tasks
• Cold start can cause latency

Use cases

• Sporadically or irregularly used applications
• Lightweight applications that perform straightforward tasks

AWS Serverless Offerings

• Compute
  • Lambda: (FaaS)
• Orchestration
  • Step Functions
• API Integration
  • API Gateway
  • AppSync
• Storage and Data Stores
  • S3: object storage and static website hosting
  • DynamoDB: fully managed NoSQL DB
  • Aurora Serverless: when you need to handle structured data
• Messaging
  • SQS (Simple Queue Service): a message queuing service
  • SNS (Simple Notification Service): a service for sending text messages and mobile notifications
• Event Routers
  • EventBridge
• Tools and Deployment
  • Amplify: (BaaS)
  • AWS CDK (Cloud Development Kit)
  • AWS SAM (Serverless Application Model)
  • AWS X-Ray: debugging your code in depth

AWS SAM

AWS SAM (Serverless Application Model) is an open-source framework to define serverless applications using YAML.

1. You can provide the simplified instruction to define your application – Lambda functions, APIS, and databases.
2. AWS SAM transforms the instructions into the fully detailed CloudFormation template.
3. AWS CloudFormation uses the transformed template to build the stack.

AWSTemplateFormatVersion : '2010-09-09'
Transform: AWS::Serverless-2021-07-11
Description: A hello world application.
Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: main.handler
      Runtime: python3.9
      CodeUri: ./src

AWS SAM CLI

You can use the AWS SAM CLI utility to test and deploy your application.

• SAM CLI launches a DOcker container.
• You can use Cloud9 Environment – Linux 2 instance – to use the pre-installed SAM CLI.

cat /etc/os-release

sam --version

sam validate

AWS Serverless Application Repository

The AWS SAR enables builders to package serverless applications and reuse these within their own AWS accounts (private – default), or share them publicly.

• Upload your application code and a manifest file known as AWS SAM (Serverless Application Model) template.
• Publish apps with AWS SAM template
• Find and deloy published applications

Security in Serverless Architecture

• Apply the principle of least privilege
  • Implement strong identity and access controls
• Apply security at all layers
  • Understand AWS shared responsibility model
  • Secure data both in transit and at rest
  • Protect your endpoints from DDOS attack
• Protect your data and credentials
• Monitor and Audit
  • Automated security monitoring
  • Enable auditing and traceability