Serverless API with Lambda

Description

Create a serverless REST API using AWS Lambda, API Gateway, and DynamoDB with CI/CD pipeline.

Objective

Deliver a scalable, serverless API with automated deployment and monitoring.

Solution

Environment Setup

  1. 1Install AWS CLI and configure credentials.
  2. 2Install Terraform or AWS SAM/Serverless Framework.
  3. 3Initialize Git repository for version control.

Define DynamoDB Table

  1. 1Create DynamoDB table with primary key (userId).
  2. 2Enable auto-scaling for read/write capacity.
  3. 3
    terraformresource "aws_dynamodb_table" "users" {
  name           = "Users"
  billing_mode   = "PAY_PER_REQUEST"
  hash_key       = "userId"

  attribute {
    name = "userId"
    type = "S"
  }
}

Create Lambda Functions

  1. 1Write Lambda functions for CRUD operations.
  2. 2Package functions with dependencies.
  3. 3
    pythonimport boto3
import json

dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('Users')

def lambda_handler(event, context):
    if event['httpMethod'] == 'POST':
        body = json.loads(event['body'])
        table.put_item(Item={'userId': body['userId'], 'name': body['name']})
        return {"statusCode": 200, "body": "User created"}
    elif event['httpMethod'] == 'GET':
        userId = event['queryStringParameters']['userId']
        response = table.get_item(Key={'userId': userId})
        return {"statusCode": 200, "body": json.dumps(response['Item'])}

Configure API Gateway

  1. 1Create REST API in API Gateway.
  2. 2Define resources (/users) and methods (GET, POST, PUT, DELETE).
  3. 3Integrate methods with Lambda functions.
  4. 4
    terraformresource "aws_api_gateway_rest_api" "api" {
  name        = "users-api"
  description = "Serverless REST API"
}

resource "aws_api_gateway_resource" "users" {
  rest_api_id = aws_api_gateway_rest_api.api.id
  parent_id   = aws_api_gateway_rest_api.api.root_resource_id
  path_part   = "users"
}

resource "aws_api_gateway_method" "get_user" {
  rest_api_id   = aws_api_gateway_rest_api.api.id
  resource_id   = aws_api_gateway_resource.users.id
  http_method   = "GET"
  authorization = "NONE"
}

CI/CD Pipeline

  1. 1Set up AWS CodePipeline with CodeBuild.
  2. 2Source stage from GitHub/CodeCommit.
  3. 3Build stage runs tests and packages Lambda.
  4. 4Deploy stage applies changes to AWS.
  5. 5
    yamlversion: 0.2
phases:
  install:
    commands:
      - pip install -r requirements.txt
  build:
    commands:
      - pytest
      - sam package --template-file template.yaml --s3-bucket mybucket --output-template-file packaged.yaml
      - sam deploy --template-file packaged.yaml --stack-name users-api --capabilities CAPABILITY_IAM

Deployment & Validation

  1. 1Deploy infrastructure with Terraform or SAM.
  2. 2Test API endpoints using Postman or curl.
  3. 3Monitor logs in CloudWatch.
  4. 4Validate CI/CD pipeline triggers on commits.

Tool Stack Used

  • ☁️AWS Lambda
  • 🔧API Gateway
  • 🔧DynamoDB
  • 🏗️Terraform/SAM
  • ☁️AWS CodePipeline
  • ☁️AWS CodeBuild
  • ☁️CloudWatch