How Do You Cache S3 Video Files at CloudFront Edge Locations?

Why the Answer Is Correct

CloudFront decides both the origin and the cache settings for each request through cache behaviors, and each behavior is tied to a URL path pattern. By adding the S3 bucket as a new origin and creating a cache behavior whose path pattern matches the video files, the distribution sends video requests directly to S3 while leaving ALB-backed requests on their existing behavior. That design is exactly what lets the video files be cached at edge locations after migration, because the objects are now fetched through a CloudFront cache behavior rather than through the ALB. Option B therefore satisfies the requirement with the native CloudFront routing and caching mechanism.

Why the Other Options Are Wrong

Option A focuses on forwarding the X-Forwarded-For header and redirecting requests, but header forwarding does not create a cache behavior for S3 and a redirect is not the same as associating S3 as a cacheable origin. Option C uses signed URLs and a custom policy, which control who may access content rather than how CloudFront routes and caches it from S3; signing alone does not add the video path to an S3 origin. Option D configures an origin group, but origin groups are failover constructs that use HTTP status codes to switch to a secondary origin, not a path-pattern routing mechanism for normal video caching. None of these alternatives establishes the necessary S3 origin plus cache behavior for the video URL path.

Community Comment Notes

As Bad_Mat noted, the correct approach is to route to Amazon S3 as a new origin and match a URL path pattern for the video files. The explanation emphasizes adding S3 as a distinct origin alongside the ALB and defining a specific cache behavior path pattern so video requests pull and cache directly from S3. No commenter argued for the header-forwarding, signed-URL, or origin-group options, and the community reasoning aligns with the CloudFront cache behavior model.