Serverless Backend Implementation & AWS Deployment

Overview

This section documents the Infrastructure-as-Code (IaC) configuration, serverless stack compilation, and AWS deployment procedure executed via AWS SAM (Serverless Application Model).

Infrastructure Template Specification (infra/template.yaml)

The serverless infrastructure is specified using the AWS Serverless Application Model specification. Below is an overview of the primary resource definitions:

AWSTemplateFormatVersion: "2010-09-09"
Transform: AWS::Serverless-2016-10-31
Description: ChromeFlashcardExtension production serverless backend stack.

Parameters:
  JwtSecret:
    Type: String
    NoEcho: true
    Description: Secret key utilized for JWT signature verification.
  AllowedOrigins:
    Type: String
    Default: "*"
    Description: Permitted origins for API Gateway CORS validation.

Globals:
  Function:
    Runtime: nodejs24.x
    Timeout: 15
    MemorySize: 256
    Environment:
      Variables:
        DATA_STORE: dynamodb
        USERS_TABLE: !Ref UsersTable
        FLASHCARDS_TABLE: !Ref FlashcardsTable
        CATEGORIES_TABLE: !Ref CategoriesTable
        EXPORT_BUCKET: !Ref ExportBucket
        JWT_SECRET: !Ref JwtSecret

Resources:
  HttpApi:
    Type: AWS::Serverless::HttpApi
    Properties:
      CorsConfiguration:
        AllowMethods: [GET, POST, PUT, DELETE, OPTIONS]
        AllowHeaders: [Content-Type, Authorization]
        AllowOrigins: !Split [",", !Ref AllowedOrigins]

  ApiFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: ../backend/
      Handler: lambda.handler
      Policies:
        - DynamoDBCrudPolicy: { TableName: !Ref UsersTable }
        - DynamoDBCrudPolicy: { TableName: !Ref FlashcardsTable }
        - DynamoDBCrudPolicy: { TableName: !Ref CategoriesTable }
        - S3CrudPolicy: { BucketName: !Ref ExportBucket }
      Events:
        HttpApi:
          Type: HttpApi
          Properties:
            ApiId: !Ref HttpApi
            Path: /{proxy+}
            Method: ANY

Build & Deployment Execution Workflow

  1. Artifact Compilation Stage:

    cd infra
sam build

    SAM validates template.yaml, pulls npm production dependencies, and builds optimized zip packages targeting the Node.js 24.x runtime.

  2. CloudFormation Stack Provisioning:

    sam deploy --guided

    Stack parameter inputs provided during deployment:

    • Stack Name: chrome-flashcard-backend
    • Target Region: us-east-1
    • Parameter JwtSecret: (Secured string provided at deployment time)
    • Parameter AllowedOrigins: *

  3. Provisioned Cloud Resources Summary:

    • AWS::Serverless::HttpApi -> Provisioned API Gateway endpoint URL: https://<api-id>.execute-api.us-east-1.amazonaws.com
    • AWS::Lambda::Function -> Execution function configured with an IAM role granting DynamoDB & S3 CRUD permissions.
    • AWS::DynamoDB::Table (3 instances) -> UsersTable, FlashcardsTable, and CategoriesTable.
    • AWS::S3::Bucket -> Private encrypted S3 export bucket with lifecycle expiration rules.

Operational Endpoint Verification

System availability was confirmed post-deployment via an automated health check against the live API Gateway HTTP API endpoint:

curl https://<api-id>.execute-api.us-east-1.amazonaws.com/api/health

Execution Output:

{"status":"ok","store":"dynamodb"}

The response verifies active production connectivity between AWS Lambda and the Amazon DynamoDB storage layer.