Download AWS S3 file directly to a directory

Question

I want to automatically save the file im downloading from AWS S3 to my application folder. Right now this can be done manually. Code below:

    router.get("/download", (req, res) => {
    //File S3 URL
    var fileKey =
        "key";

    AWS.config.update({
        accessKeyId: IAM_USER_KEY,
        secretAccessKey: IAM_USER_SECRET,
        Bucket: BUCKET_NAME
    });

    var s3 = new AWS.S3();
    var file = fs.createWriteStream("test.csv");

    var options = {
        Bucket: "name",
        Key: fileKey
    };

    res.attachment(fileKey);

    var fileStream = s3
        .getObject(options)
        .createReadStream()
        .on("error", error => {
        console.log(error);
        res.json({ error: "An error has occured, check console." });
        })
        .on("httpData", function(data) {

        file.write(data);
        })
        .on("httpDone", function() {
        file.end();
        });

    fileStream.pipe(res);
    //   fse.writeFileSync("text.csv");
    });

As mentioned before, the file can be download and saved manually. But how can write the file and save it automatically in an specific folder?

Thank you

Answer 1

Here's an example of downloading an S3 object to a specific local file:

const AWS = require('aws-sdk');
var s3 = new AWS.S3({apiVersion: '2006-03-01'});
var params = {Bucket: 'mybucket', Key: 'test.csv'};
var file = require('fs').createWriteStream('/tmp/test.csv');
s3.getObject(params).createReadStream().pipe(file);

Answer 2

The code for jarmod's answer, promisified:

const AWS = require('aws-sdk');
const s3 = new AWS.S3({apiVersion: '2006-03-01'});
const params = {Bucket: 'mybucket', Key: 'test.csv'};
const file = require('fs').createWriteStream('/tmp/test.csv');

new Promise((resolve, reject) => {
  const pipe = s3.getObject(params).createReadStream().pipe(file);
  pipe.on('error', reject);
  pipe.on('close', resolve);
});