Rewrite volume storage, refactor some of the old code #16
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Wrote a doc for which directories exist for volumes and how they are supposed to be managed. It will be used for storage implementation (#7)
The plugin now determines the active mounts for a volume (not overlay) using the activemounts/ subdirectory corresponding to the volume. It resolves the race condition problem with parallel mounts/unmounts on the same volume. Gets us closer to fixing #15! However, not there yet, as we are still using go's `map`, which is thread-unsafe.
- Removed the `volumes` field of `Driver`, instead introduced the metadata.json per-volume internal file, which currently stores the base directory path and the volatility. - Rewrote the methods that used the in-memory volume storage to use the filesystem instead. - Renamed dotBaseDir to `dotRootDir` and turned it into a field of `Driver`. Fixes #7. As far as I can see, fixes #15! The code is starting to get bulky, probably, restructuring is needed...
A large refactoring! Created several files and restructured the code between them, renamed a couple of entities, wrote documentation for some non-trivial functions/methods. Also fixed a few minor bugs: - A file descriptor leak in `lockedFile.Open` if an error occurs in `syscall.Flock` - An error returned on every unmount, even when no actual error occurred
When creating a `DockerOnTop` object, go through the existing volumes with some sort of a health check: if an overlay is mounted for the volume, do nothing with it, otherwise ensure the active mounts and the workdir/ directory are clean - this protects from a case when the machine is rebooted without giving the docker daemon enough time to properly clean up.
kolayne
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Jun 4, 2023
When starting, the plugin now checks for each volume whether its state is clean, dirty but overlay-unmounted, or overlay-mounted. Info logs describe all the detected volumes, a detailed warning log message is issued if there's at least one overlay-mounted volume to explain which consequences it might have.
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kolayne
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Jun 5, 2023
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Fixed some docs/comments, variables names, log messages, code style issues
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The following features are introduced by this PR:
NewDockerOnTop) all the volumes and their metadata is accessed in a thread-safe manner, synchronized via filesystem access (there's a new requirement: the/var/lib/docker-on-top/is located on a filesystem that supports theflocksystem call) (fixes Thread-safety! #15)