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[ S3 Access Logs ]

- For audit(품질검사) purpose, you may want to log all access to S3 buckets

- Any request made to S3, from any account, authorized or denied, will be logged into another S3 bucket

- That data can be analyzed using data analysis tools

- Or Amazon Athena as we'll see later in this section

# Warning

로깅 버킷을 로깅 모니터링 대상으로 두면 로깅 루프가 되어 버킷 사이즈가 기하급수적으로 커짐

* Do not set your logging bucket to be the monitored bucket

  It will create logging loop, and your bucket will grow in size exponentially(기하급수적으로)

[ S3 Replication ]

- Must enable versioning in source and destination

- Cross Region Replication (CRR)

- Same Region Replication (SRR)

- Buckets can be in different accounts

- Copying is asynchronous

- Must give proper IAM permissions to S3

- CRR Use cases : compliance, lower latency access, replication across accounts

- SRR Use cases : log aggregation, live replication between production and test accounts

- After activating, only new objects are replicated (not retroactive)

- For Delete operations :  any delete operation is not replicated

  If you delete without a version ID, it adds a delete marker, not replicated

  If you delete with a version ID, it deletes in the source, not replicated

- There is no "chaining" of replication

  If bucket I has replication into bucket 2, wich has replication into bucket 3

  Then objects created in bucket 1 are not replicated to bucket 3

[ S3 Pre-signed URLs ]

- Can generate pre-signed URLs using SDK or CLI

  for downloads (easy, can use the CLI)

  for uploads (harder, must use the SDK)

- Valid for a default of 3600 seconds, can change timeout with --expires-in [TIME_BY_SECONDS] argument

- Users given a pre-signed URL inherit the permissions of the person who generated the URL for GET/PUT

Examples :

  1) Allow only logged-in users to download a premium video on your S3 bucket

  2) Allow an ever changing list of users to download files by generating URLs dynamically

  3) Allow temporarily a user to upload a file to a precies location in our bucket