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The runtime spec says the mount destination is a path inside the container, but runc also accepts a destination prefixed with the host rootfs path, stripping the prefix. This dates back to commit 087caf6, when Docker used to pass the full host path to the mountpoint. Add a comment explaining it. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
The test_mount_order test used host rootfs paths as mount destinations, relying on runc stripping the rootfs prefix, which is a legacy runc behavior not described by the runtime spec. Use paths inside the container instead, as the spec says, so the test can also be used with other runtimes (e.g. crun). Bind mount sources inside the container rootfs are still used, as this is what the test is about. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
kolyshkin
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Oct 1, 2026
| rootfs := root.Name() | ||
| // The runtime spec says the destination is a path inside the container, | ||
| // but for legacy reasons (see commit 087caf69) a destination with the | ||
| // host rootfs path prefix is also accepted, and the prefix is stripped. |
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Maybe add a warning for such paths in 1.6 and remove those in 1.8?
This was referenced Oct 1, 2026
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The
test_mount_ordertest used host rootfs paths as mount destinations, relying on runc stripping the rootfs prefix from a destination. This is legacy runc behavior (dating back to commit 087caf6, when Docker passed full host paths), not something described by the runtime spec, which says the destination is a path inside the container.Use container paths for destinations, so the test can be used with other runtimes (e.g. crun). Bind mount sources inside the container rootfs are still used, as this is what the test is about.
While at it, add a comment explaining the legacy behavior in the code.