How Lambda@Edge works with requests and responses
When you associate a CloudFront distribution with a Lambda@Edge function, CloudFront intercepts requests and responses at CloudFront edge locations. You can execute Lambda functions when the following CloudFront events occur:
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When CloudFront receives a request from a viewer (viewer request)
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Before CloudFront forwards a request to the origin (origin request)
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When CloudFront receives a response from the origin (origin response)
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Before CloudFront returns the response to the viewer (viewer response)
If you're using AWS WAF, the Lambda@Edge viewer request is executed after any AWS WAF rules are applied.
For more information, see Work with requests and responses and Lambda@Edge event structure.
