One Bucket, Two Terraform Owners - the Last apply Wins

Originally published at blog.whynext.app . It started as an ordinary cleanup problem. Users upload media files (recordings and images) through presigned URLs. The server issues an upload URL, the client uploads straight to S3, then calls a commit API to say "register this key as a real asset." The problem is what happens when someone gets a presign but never commits. The app crashes, the network drops, the user leaves the screen, and the bucket is left with an object that isn't registered anywhere. I wanted a lifecycle rule to clean these up, but there was no way to write one. Committed and uncommitted objects were mixed under the same prefix, so any rule that says "delete old things" would delete real assets too. A daily upload quota kept the pile from growing fast, but the fact remained: there was no path to reclaim the space. The design: what isn't committed lives in tmp The backbone of the fix is key namespace separation. presign issues a temporary key under the tmp/ prefix. When commit passes validation (existence check via HEAD, Content-Type, size limit), it promotes the object to its final key with CopyObject and deletes the tmp original. Objects whose commit never arrives stay in tmp/ , and a lifecycle rule expires them after 7 days. Now the lifecycle rule only has to look at tmp/ . Real assets are outside its blast radius from the start. The clients didn't need to change. I read all three upload flows to confirm this: every one of them uses the key returned in the commit response for its follow-up calls, so the server can change the key shape without them noticing. Commits for old-format keys already in flight at deploy time still go through the existing path. One trap here. This bucket has versioning enabled. On a versioned bucket, expiration doesn't delete an object. It only adds a delete marker, and the original bytes stay behind as a noncurrent version. Without a paired noncurrent_version_expiration (1 day), the cleanup runs and not a single byte is rec