AWS Serverless CSV Processor

This project is a serverless application that processes CSV files uploaded to an S3 bucket using AWS Lambda (Java with Spring Boot) and stores the data into a DynamoDB table. It also archives the original CSV and stores a JSON version.

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📦 Prerequisites

• AWS CLI (aws configure to set credentials)
• AWS SAM CLI
• Docker
• Java 11 and Gradle

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🗂 Project Structure

aws-serverless-s3-csv-lambda/
├── build.gradle
├── template.yaml
├── build.sh
└── src/main/java/com/letzautomate/
    ├── lambda/LambdaHandler.java
    ├── service/FileProcessorService.java
    ├── service/S3Archiver.java
    ├── service/JsonOutputService.java
    └── model/User.java

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📝 SAM Template: template.yaml

Defines the S3 bucket, Lambda function, and DynamoDB table.

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Globals:
  Function:
    Timeout: 30
    Runtime: java11
    MemorySize: 1024
Resources:
  InputBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: s3-csv-user-processor-input

  CsvProcessingFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: .
      Handler: com.letzautomate.lambda.LambdaHandler
      Policies:
        - AmazonS3FullAccess
        - AmazonDynamoDBFullAccess
      Events:
        S3Upload:
          Type: S3
          Properties:
            Bucket: !Ref InputBucket
            Events: s3:ObjectCreated:*
      Environment:
        Variables:
          OUTPUT_BUCKET_NAME: !Ref InputBucket
          ARCHIVE_PREFIX: "archive/"
          OUTPUT_PREFIX: "output/"

  UserTable:
    Type: AWS::DynamoDB::Table
    Properties:
      BillingMode: PAY_PER_REQUEST
      AttributeDefinitions:
        - AttributeName: employeeId
          AttributeType: S
      KeySchema:
        - AttributeName: employeeId
          KeyType: HASH

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🚀 Deployment Script: build.sh

#!/bin/bash

set -e
STACK_NAME="csv-lambda-dynamo"
REGION="us-east-1"
BUCKET_NAME="sam-artifacts-ramakrishna-csv-lambda"

if ! aws s3 ls "s3://$BUCKET_NAME" 2>&1 | grep -q 'NoSuchBucket'; then
  echo "✅ Bucket exists"
else
  aws s3 mb "s3://$BUCKET_NAME" --region "$REGION"
fi

sam build

sam deploy   --stack-name "$STACK_NAME"   --s3-bucket "$BUCKET_NAME"   --region "$REGION"   --capabilities CAPABILITY_IAM   --no-confirm-changeset

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🧠 Main Logic

FileProcessorService does the following:

1. Downloads CSV from S3.
2. Parses it into User objects.
3. Inserts them into DynamoDB.
4. Saves a JSON file.
5. Archives the CSV.

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📤 To Trigger

Upload a file:

aws s3 cp users.csv s3://s3-csv-user-processor-input/

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✅ Final Output

Component	Status
Lambda Build	✅
S3 Trigger	✅
DynamoDB Write	✅
Archiving	✅
Logging	✅