Whiteouts out-of-band
Table of contents
- What are the challenges that we are trying to solve?
- What ideas do we have for how to address these challenges?
- How do these ideas break down into…
- Questions?
- What pre-existing work or software can support these ideas?
- Relevant OCI Issues
What are the challenges that we are trying to solve?
White-outs are in-band with special filenames. That is, layer tarballs
contain empty files with a .wh. prefix to indicate something has been
deleted. This makes it impossible to simply unpack tarballs and making those
names impossible to store.
Aleksa Sarai has critiqued white-out files in greater detail. It seems the way the spec came about is that Docker simply tarred up the AUFS layers and that that became the standard image format; i.e., the format wasn’t carefully designed but arose as a result of one existing implementation’s way to get a minimally-viable product working quickly.
What ideas do we have for how to address these challenges?
Store white-outs out of band, e.g. as a JSON blob accompanying a layer tarball.
How do these ideas break down into…
Already existing OCI specs?
Image spec.