1 Commits

Author	SHA1	Message	Date
Colin Walters	f81b9fa166	sysroot: Rework /var handling to act like Docker VOLUME /var ... We've long struggled with semantics for `/var`. Our stance of "/var should start out empty and be managed by the OS" is a strict one, that pushes things closer to the original systemd upstream ideal of the "OS state is in /usr". However...well, a few things. First, we had some legacy bits here which were always populating the deployment `/var`. I don't think we need that if systemd is in use, so detect if the tree has `usr/lib/tmpfiles.d`, and don't create that stuff at `ostree admin stateroot-init` time if so. Building on that then, we have the stateroot `var` starting out actually empty. When we do a deployment, if the stateroot `var` is empty, make a copy (reflink if possible of course) of the commit's `/var` into it. This matches the semantics that Docker created with volumes, and this is sufficiently simple and easy to explain that I think it's closer to the right thing to do. Crucially...it's just really handy to have some pre-existing directories in `/var` in container images, because Docker (and podman/kube/etc) don't run systemd and hence don't run `tmpfiles.d` on startup. I really hit on the fact that we need `/var/tmp` in our container images by default for example. So there's still some overlap here with e.g. `/usr/lib/tmpfiles.d/var.conf` as shipped by systemd, but that's fine - they don't actually conflict per se.	2024-02-09 17:46:12 -05:00