Static JS files served from S3 via CloudFront lead to intermittent CORS issues
We have an S3 bucket with static JS bundles. Here are the CORS settings of that bucket:
Each file in the bucket has the following meta data (we use filename versioning to prevent caching issues):
Here are the behavior settings of our CloudFront distribution:
We serve those JS files to our web application for browsers. It works for the great majority of visitors of our website, but every now and again we get report of users who cannot load the JS files because of missing CORS headers (Access-Control-Allow-Origin: *).
We have also invalidated CloudFront cache and have also done "cache busting" by renaming all objects - but the problem remains.
Why is that?
- Newest
- Most votes
- Most comments
=>Intermittent CORS issues with static JS files served from S3 via CloudFront can often be traced back to caching behavior and propagation delays. Here's a simplified conclusion:
=.Caching Issues: CloudFront or the browser might be caching an old version of the file without the correct CORS headers. Ensure that CloudFront is set to forward the Origin header to S3 and that S3 CORS settings are correctly applied.
=.Propagation Delays: Changes to S3 bucket CORS settings or CloudFront distribution settings can take some time to propagate. Ensure you invalidate the CloudFront cache after making changes.
=.Consistent Settings: Double-check that all S3 objects have the correct metadata and headers applied consistently.
To mitigate these issues:
=>Verify CloudFront behavior settings to ensure the Origin header is forwarded.
=>Invalidate the CloudFront cache when updating CORS settings.
=.Ensure S3 bucket CORS configuration allows the necessary methods and origins.
Relevant content
- asked 2 years ago
- asked 10 months ago
AWS OFFICIALUpdated 2 years ago- AWS OFFICIALUpdated a year ago
- AWS OFFICIALUpdated a year ago
- AWS OFFICIALUpdated 2 years ago
This answer is simply general and unspecific. Have you checked our settings in the screenshots above? Is there something specific that is wrong and needs to be changed?