Get File From S3 bucket using Serverless and Node js - amazon-web-services

Question

I am new to Serverless and AWS also. So My requirement is like. I need to download a file from S3. I have tried in many ways. I read many articles but could not find a proper document for this purpose.
So What I did was, I created a boilerplate using Serverless and got all the files like handler.js, serverless.yml
I need to know the correct steps to download a file from S3.
What I tried is.
Handler.js
const AWS = require('aws-sdk');
const S3= new AWS.S3();
exports.hello = async (event, context) => {
console.log(`Hi from Node.js ${process.version} on Lambda!`)
S3.getObject({Bucket: '*******', Key: '******'}).promise().then( data =>{
return {
statusCode: 200,
body: data
})
}
Serveless.yml
service: node11
custom:
bucket: *********
provider:
name: aws
runtime: provided # set to provided
stage: dev
region: us-east-1
iamRoleStatements:
- Effect: Allow
Action:
- s3:*
Resource: "arn:aws:s3:::${self:custom.bucket}/*"
functions:
hello:
handler: handler.hello
events:
- http:
path: /
method: get
layers: # add layer
- arn:aws:lambda:us-east-1:553035198032:layer:nodejs11:3
Whatever I did, I am always getting an error like INTERNAL SERVER ERROR.
What is the proper way to get the file from S3?

Answer 1

Try this:
const AWS = require('aws-sdk');
const S3= new AWS.S3();
exports.hello = async (event, context) => {
try {
console.log(`Hi from Node.js ${process.version} on Lambda!`);
// Converted it to async/await syntax just to simplify.
const data = await S3.getObject({Bucket: '*******', Key: '******'}).promise();
return {
statusCode: 200,
body: JSON.stringify(data)
}
}
catch (err) {
return {
statusCode: err.statusCode || 400,
body: err.message || JSON.stringify(err.message)
}
}
}
and ensure that in serverless.yml you've set runtime: nodejs8.10 under provider.
Lambda response body must be a string as defined here.