AWS Lambda return a file - scala

Question

I'm reading a CSV file from S3 using Lambda and want to return that file to the caller of the lambda function. I don't want to print the file through outputstream - I want to return the actual file. Is there a way to do this? I get the S3 file like this:
override def handleRequest(inputStream: InputStream,
outputStream: OutputStream,
context: Context): Unit = {
...
val s3File = s3Client.getObject(bucketName, bucketKey)
}
How can I return the actual file (as opposed to converting it to String and printing via outputStream)?

Answer 1

The above can be done using nodejs aws lambda with express server. You could use aws provided package
// lambda.js
'use strict'
const awsServerlessExpress = require('aws-serverless-express')
const app = require('./app')
const server = awsServerlessExpress.createServer(app)
exports.handler = (event, context) => { awsServerlessExpress.proxy(server, event, context) }
// app.js
// refer the examples for complete code
// https://github.com/awslabs/aws-serverless-express/blob/master/examples/basic-starter/app.js
...
router.get('/download', (req, res) => {
s3.getObject({Bucket: myBucket, Key: myFile},function(err,data){
if (err) {
// report error and return the server error
return res.status(500).send("Error!");
}
// set the http Headers
res.set("Content-Length",data.ContentLength)
.set("Content-Type",data.ContentType);
// send the data
res.send(data.Body);
});
});
...
PS: I have not tested the above code.