I'm trying to set up a reverse proxy on a subfolder of our domain (example.com/sub) to show content from a site sitting on a different domain/server. I would like to access that site on the same domain subfolder for SEO purposes.
I have a CloudFront distribution set up for the whole domain. On the same distribution, I have an additional behavior /sub* Viewer request linked to a Lambda@Edge function.
In that lambda function, I'm returning some HTML. For testing, I'm using code straight from AWS docs.
'use strict';
const content = `
<\!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Simple Lambda@Edge Static Content Response</title>
</head>
<body>
<p>Hello from Lambda@Edge!</p>
</body>
</html>
`;
exports.handler = (event, context, callback) => {
/*
* Generate HTTP OK response using 200 status code with HTML body.
*/
const response = {
status: '200',
statusDescription: 'OK',
headers: {
'cache-control': [{
key: 'Cache-Control',
value: 'max-age=100'
}],
'content-type': [{
key: 'Content-Type',
value: 'text/html'
}]
},
body: content,
};
callback(null, response);
};
This works as expected. But when I try to return a more complex HTML for example
exports.handler = async (event, context, callback) => {
console.log(event);
const response = await fetch('https://www.nbcnewyork.com');
const content = await response.text();
const res = {
status: '200',
statusDescription: 'OK',
headers: {
'cache-control': [{
key: 'Cache-Control',
value: 'max-age=100'
}],
'content-type': [{
key: 'Content-Type',
value: 'text/html'
}]
},
body: content,
};
callback(null, res);
};
When I GET the example.com/sub I'm getting the error below.
502 ERROR
The request could not be satisfied.
The Lambda function returned invalid JSON: The JSON output is not parsable. We can't connect to the server for this app or website at this time. There might be too much traffic or a configuration error. Try again later, or contact the app or website owner.
If you provide content to customers through CloudFront, you can find steps to troubleshoot and help prevent this error by reviewing the CloudFront documentation.
Generated by cloudfront (CloudFront)
Request ID: *
In CloudWatch for CloudFront/LambdaEdge I'm also seeing these events:
2022-04-08T12:31:50.000+02:00 (2k-5BGOaTxD_Ll51dVhJbBRN0rQY4yjju4k9TEPQcpgzl1MZa-vYAA==) INFO START processing EventType: viewer-request LambdaFunctionARN: arn:aws:lambda:eu-central-1:*:1 Method: GET URI: /sub
2022-04-08T12:31:50.000+02:00 (2k-5BGOaTxD_Ll51dVhJbBRN0rQY4yjju4k9TEPQcpgzl1MZa-vYAA==) INFO Invoking LambdaFunctionARN: arn:aws:lambda:eu-central-1:*:1 Region: eu-central-1
2022-04-08T12:31:50.000+02:00 (2k-5BGOaTxD_Ll51dVhJbBRN0rQY4yjju4k9TEPQcpgzl1MZa-vYAA==) INFO Response received from Lambda: RequestId: *
2022-04-08T12:31:50.000+02:00 (2k-5BGOaTxD_Ll51dVhJbBRN0rQY4yjju4k9TEPQcpgzl1MZa-vYAA==) ERROR Validation error: The Lambda function returned an invalid json output, json is not parsable.
2022-04-08T12:31:50.000+02:00 (2k-5BGOaTxD_Ll51dVhJbBRN0rQY4yjju4k9TEPQcpgzl1MZa-vYAA==) INFO END processing EventType: viewer-request LambdaFunctionARN: arn:aws:lambda:eu-central-1:*:f
Any ideas about what I'm doing wrong?
Regards, Primoz