Change CloudFront response using lambda#Edge - request

Question

I have been trying to use lambda#edge to add the CloudFront-viewer-country header to my response, I managed to trigger the function and its working, but I can't see any logs in cloudWatch, cloudWatch is only logging the test which is done on the function page not the real test that got trigged by visiting the website, I googled how to find the logs and found out that its in cloudWatch of the nearest region that received the request, but I could not find any.
I have tried two methods to change my response one of them was on stack overflow answers: https://stackoverflow.com/questions/48633610/how-do-i-get-cloudfront-viewer-country-to-appear-in-response-headers
'use strict';
exports.handler = (event, context, callback) => {
const request = event.Records[0].cf.request;
const response = event.Records[0].cf.response;
if(request.headers['cloudfront-viewer-country'])
{
response.headers['cloudfront-viewer-country'] = request.headers['cloudfront-viewer-country'];
}
return callback(null,response);
};
This method when gets tested from the lambda page it works, but when I test by accessing the website I get 503 server error: The Lambda function associated with the CloudFront distribution is invalid or doesn't have the required permissions.
So can someone help in these permissions, please note that I have the following policy on my s3 bucket which static hosts my website:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "PublicReadForGetBucketObjects",
"Effect": "Allow",
"Principal": "*",
"Action": "s3:*",
"Resource": "arn:aws:s3:::outfityard-app-client/*"
}
]
}
The other method that I have tried was using the following function in my lambda:
'use strict';
exports.handler = (event, context, callback) => {
const request = event.Records[0].cf.request;
const headers = request.headers;
const uri = request.uri === "/index.html" ? "/" : request.uri;
var countryCode = null;
if(headers["cloudfront-viewer-country"]) {
countryCode = headers["cloudfront-viewer-country"][0].value;
}
console.log(`Country detected: '${countryCode}'`);
if (countryCode !== "US") {
const response = {
status: "200",
statusDescription: "Found",
headers: {
["cache-control"]: [
{
key: "Cache-Control",
value: "no-cache, no-store, private"
}
],
["cloudfront-viewer-country"]: [
{
key: "cloudfront-viewer-country",
value: countryCode
}
]
}
};
callback(null, response);
} else {
callback(null, request);
}
};
This method is returning the expected response but nothing gets loaded from my website which I don't understand why! here is the response headers that I received:
Content-Type →text/html
Content-Length →1217
Connection →keep-alive
Server →CloudFront
Date →Fri, 16 Aug 2019 11:37:19 GMT
X-Cache →LambdaExecutionError from cloudfront
Via →1.1 9891f2220bf61a27cb1f26085ab3703d.cloudfront.net (CloudFront)
X-Amz-Cf-Pop →CDG3-C2
X-Amz-Cf-Id →D542SzvAsMYAXIOcBUwHWEB5_lAf41t1wWULh6LcXwagAvjFRvH5nA==
I have used the following and its working fine but I don't know if its the right way to do it:
'use strict';
exports.handler = (event, context, callback) => {
const request = event.Records[0].cf.request;
const response = event.Records[0].cf.response;
const value = request.headers['cloudfront-viewer-country'][0].value;
const key = request.headers['cloudfront-viewer-country'][0].key;
response.headers['cloudfront-viewer-country'] = [{key: key, value: value}];
return callback(null,response);
};