Add CORS headers to HTTP responces with AWS Lambda for API Gateway

index.js

const axios = require('axios');

exports.handler = async (event) => {
    const response = await axios.get(process.env.ENDPOINT_URL, { params: event.queryStringParameters });
    return { statusCode: 200, headers: { "access-control-allow-origin": "*" },  body: JSON.stringify(response.data) };
};