AWS Cloudfront 如何知道源何时更新？

Question

I have configured cloudfront distribution with OAI and S3 as origin. So the request from user goes from User -> Edge Location -> CloudFront-> S3 . Based on the documentation CloudFront can also cache frequently accessed objects.
Question:
1>When object is updated in S3 how does cloudfront know that the object is changed at origin? Is there any trigger from S3-> CloudFront -> Edge?
2>If there is no trigger, then how do we trigger cloudfront redistribution of objects from S3? ( this is typically after code deployment to s3)

Answer 1

When object is updated in S3 how does cloudfront know that the object is changed at origin? Is there any trigger from S3-> CloudFront -> Edge?

It does not "know" that immediately, until objects in cache expire. You have to refresh catch manually or build an automation for that yourself, to for cache invalidation.

If there is no trigger, then how do we trigger cloudfront redistribution of objects from S3? ( this is typically after code deployment to s3)

You have to invalidate the cache yourself, as explained earlier.