How to make S3 delete old files on its own (lifecycle rules)

S3 is cheap per GB, but it does not delete anything on its own. The nightly backups from three years ago, the previous versions of every file, the uploads that were cut off halfway: all of it is still there, taking up space and being charged. A lifecycle rule is an automatic rule you tell the bucket once: "anything older than 90 days, delete it" or "anything untouched for 30 days, move it to cheap storage". From then on, S3 does it every day without anyone having to remember.

Step by step

1. Decide what you want to happen and when

   Three questions: how long do you need to keep the backups? (90 days is usually reasonable; a year if there is a legal obligation). How many previous versions of a file do you want to be able to recover? (30 days of previous versions gives plenty of margin for an accidental deletion). Are there files that are hardly ever read but have to be kept? (candidates for cheap storage). Write down the answers: they are the numbers for the rule.

2. Open the bucket's rules

   S3 console, go into the bucket, Management tab, Create lifecycle rule. Give it a name that says what it does (limpiar-copias-90-dias).

3. Choose what it applies to

   If you want it to apply to the whole bucket, tick Apply to all objects in the bucket. If only to one folder, choose Limit the scope of this rule using one or more filters and type the prefix (copias/, with the trailing slash). You can create several rules with different prefixes: one for backups, another for logs, and leave untouched the folders that must be kept forever.

4. Tick the actions

   For a backup folder, the usual thing is to tick:

   • Expire current versions of objects: 90 days after creation. This deletes old backups.
   • Permanently delete noncurrent versions of objects: 30 days after becoming noncurrent. This cleans up previous versions and deleted items.
   • Delete expired object delete markers and delete incomplete multipart uploads after 7 days. This cleans up the invisible rubbish and should be on every bucket.

   If instead of deleting you want to cut costs, tick Transition current versions of objects between storage classes: to Standard-IA after 30 days and, if it is long-term archive, to an archive class after 90. Careful: archive classes take hours to return the file and charge for retrieving it.

5. Review and save

   The final screen summarises in a timeline what happens to each object at 7, 30 and 90 days. Read it slowly: an "expire after 90 days" rule applied to the whole bucket will also delete what you wanted to keep. If the summary says what you expected, Create rule.

6. Check after a few days

   Rules run once a day, in the early hours, and the first pass can take more than a day to show. In the bucket's Metrics tab you will see the total size go down. If you have many objects, turn on the inventory or look at the S3 cost in Cost Explorer over the following weeks: it should drop and level off.

What can go wrong