Read a file line by line from S3 in Node.js

January 7, 2022

I had to do this recently, and it’s actually quite straightforward… once you know what to do.

One problem I faced was that all the blogs and Stack Overflow answers I found were about the AWS SDK v2 and they don’t work with v3. The following code has been tested with AWS SDK v3.45.

const AWS = require("@aws-sdk/client-s3");
const readline = require("readline");

const readFile = async (bucket, filename) => {
    const s3 = new AWS.S3();

    const file = await s3.getObject({
        Bucket: bucket,
        Key: filename
    });

    const reader = readline.createInterface({ input: file.Body });

    for await (const line of reader) {
        // process each line
    }
}