Hacker News Reader

"Thus it seems that if you leave a file on disk between steps in your Dockerfile, the space will not be reclaimed when you delete the file."

This must be a bug? Why should it legitimately behave this way?

View on HN

From what I understand, docker caches the state of its world during each step. So you add a file, it caches, remove the file, it can't free that space from the layered filesystem. But if you create & remove in the same `RUN` command, it never gets persisted as a step, so doesn't take up space.

I don't think its a bug. Its due to the layered filesystem architecture. Deleting a file in a later build step is not going to remove it from the previous layers. It just adds a new layer with meta-data saying the file has been removed.

Reply on news.ycombinator.com