HowTo: Create AWS Lambda with Cloudformation

index.js

// For simplicity, error handling is not included
const axios = require('axios')
const AWS = require('aws-sdk');

const region = process.env['AwsRegion']
AWS.config.update({region});

const url = process.env['ExchangeRateURL']

const bucket = process.env['S3Bucket']
const objectKey = process.env['S3ObjectKey']

const cacheMaxAge = process.env['S3ObjectCacheMaxAge']

exports.getExchangeRate = async (event) => {
  const res = await axios.get(url)
  const params = {
    Body: JSON.stringify(res.data),
    Bucket: bucket,
    Key: objectKey,
    ContentType: 'application/json',
    CacheControl: 'max-age=' + cacheMaxAge
  }

  const s3 = new AWS.S3();
  await s3.putObject(params).promise()

  return res.data
}