How to Clear Amazon S3 and Cloudfront Cache or Synchronize Their Cache

1. What is the problem with Amazon CloudFront not reflecting S3 updates?

The issue occurs when S3 metadata (e.g., Content-Type) is updated, but CloudFront continues serving cached content with outdated metadata, like application/x-mp4 instead of video/mp4. CloudFront serves the old cached version even after manual updates or running a cron job.

2. Why is CloudFront showing outdated metadata?

CloudFront caches both the content and metadata (like Content-Type) at its edge locations. Once cached, CloudFront will continue serving this stale data until:

1. The cache expires (based on TTL settings).
2. Cache invalidation is manually triggered.

3. How can I ensure CloudFront reflects the S3 updates?

a. Manually Invalidate CloudFront Cache
-> AWS Console Steps:

• Open CloudFront in AWS.
• Select your distribution.
• Go to the Invalidations tab and create an invalidation for the updated files (e.g., /path/to/video.mp4).

-> AWS CLI Example:
aws cloudfront create-invalidation \
--distribution-id YOUR_DISTRIBUTION_ID \
--paths "/path/to/video.mp4"

b. Use Proper Cache-Control Headers
Ensure S3 objects have correct Cache-Control headers to define how long objects should be cached by CloudFront. Example:
Cache-Control: max-age=60

c. Automate Invalidation in Cron Job
Update your cron job script to include CloudFront cache invalidation each time it updates metadata.

4. What are the best practices to avoid this issue?

• Use Content Versioning
• Automate Invalidation
• Set Correct TTL