How To Read S3 File/Image Using Lambda Functions

Here i share how you preview image using API Gateway, S3 and Lambda Function. This function build on Node.js 18.x

Create A Lambda Function

Give a function name, Runtime, Architecture.

After creating the function. Need to Add trigger with S3 and API Gateway

Add Trigger at S3 and API Gateways

Here 1st i adding S3 as a trigger with this function.

Give the selected bucker name and event type. After that click Add.

2nd adding the API Gateway

At API Gateway, create intent as a create a new API , Set API Type is HTTP API , At Security, Select Open. Then Click Add Button.

Trigger configuration done.

Adding Code

Now Add Code at index.js

const AWS = require('aws-sdk');
const s3 = new AWS.S3();
exports.handler = async (event, context) => {

  const bucketName = '<BUCKET_NAME>';
  const imageKey = '<IMAGE_KEY/NAME>'; // Replace 'your-image-key.jpg' with your actual image key

  try {
    const params = {
      Bucket: bucketName,
      Key: imageKey,
    };

     const s3Object = await s3.getObject(params).promise();
    if (!s3Object || !s3Object.Body) {
      return {
        statusCode: 404,
        body: JSON.stringify({ message: 'Image not found' })
      };
    }
    const imageData = Buffer.from(s3Object.Body, 'binary').toString('base64') ;
    return {
      statusCode: 200,
      headers: {
        'Content-Type': 'image/jpeg'
      },
      isBase64Encoded: true,
      body: imageData

    };
  } catch (error) {
    return {
      statusCode: 500,
      body: JSON.stringify(error.message)
    };
  }
};

Here a a require package needed. But you can’t add node_modules at Lambda function. Need to create a layer.

Goto Lambda Function > Layer (At Additional resources)