CODEWITHSUNDEEP
amazon-cloudfrontcloudfront-functions
Sflagg
Sflagg

Reputation: 257

CloudFront function cache-control header not changing the custom response header set in the CF distribution

I have a CloudFront function set up to set cache-control headers per status code. For status code 200 I want to use the custom response header cache-control set on my CloudFront distribution of max-age=604800, s-maxage=2592000. And for the other response codes I want the CloudFront function to set the cache-control as you can see in the following code. Every response is coming back with the cache-control of max-age=604800, s-maxage=2592000. How can I make it so the responses come back with the cache-control set by my CF function?

var DEBUG = true;

function logToConsole(message, force) {
    if (DEBUG || force !== undefined) console.log(message);
}

var cacheControlHeaders = {
    404: 'max-age=300',
    403: 'max-age=0',
    400: 'max-age=0',
    500: 'max-age=0',
    503: 'max-age=0',
    504: 'max-age=0'
};

function handler(event) {
    logToConsole(event);
    try {
        var statusCode = event.response.statusCode;
        logToConsole(statusCode);
        
        if (cacheControlHeaders.hasOwnProperty(statusCode)) {
            var cacheControlValue = cacheControlHeaders[statusCode];
            logToConsole(`Setting Cache-Control for ${statusCode} response`);
            event.response.headers['cache-control'] = { value: cacheControlValue };
        }
    } catch (error) {
        logToConsole(error, true);
    }

    return event.response;
}

I referenced this AWS article as a starting point https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/example-function-add-cache-control-header.html

I am using the JS Runtime 1.0

I have inspected my CloudFront distributions behaviors and can't place where I am going wrong.

I have the CF distribution referencing a response headers policy with a custom header with cache-control max-age=604800, s-maxage=2592000 and origin override enabled.

Does the response headers policy with a custom header take precedence over a CF function setting this header value?

Upvotes: 0

Views: 182

Answers (1)

Sflagg
Sflagg

Reputation: 257

It turns out that this is not possible. Per https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/edge-function-restrictions-all.html#function-restrictions-status-codes

"CloudFront does not invoke edge functions for viewer response events when the origin returns HTTP status code 400 or higher."

So I am going to set a shorter cache control in the custom response header and then set a longer one for 200 in the CloudFront function.

Upvotes: 0

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