Give the machine's storage the shape its containers have - #872
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This was referenced Aug 27, 2026
The reaper that runs at a concurrency of one deletes everything in the test directory except the unpacked rootfs it means to preserve. It held that rootfs path as FileManager reports it, under /var, and compared it against the entries of contentsOfDirectory, which reports them under /private/var, so the preserved path never matched any entry and the rootfs was deleted along with the per-test files. The unpack coordinator still held it as unpacked, so the next test opened a rootfs that was no longer there and failed with a missing file error. Resolve both sides with resolvingSymlinksInPathWithPrivate, which exists for this difference between the two views of the same directory.
Tests guarded for Linux are compiled out on macOS, so `make test` reports success without having run them, and nothing says so. The target that does run them is not mentioned anywhere outside the makefile.
The default kernel the tests fetch had drifted from the one users run. container installs kata 3.28.0 and its 6.18.15 kernel, while these tests fetched 3.17.0, so the suite exercised a guest with a different feature set to the one it is meant to represent. Nested runtimes are the visible case: 3.17.0 was built without nf_tables, so a docker daemon inside a container fails there and works on what ships. Kata moved from xz to zstd between those releases, so the archive is no longer named for its compression and tar is left to recognise it rather than being told, which also holds if the format changes again.
A test's rootfs clones, init block, and writable layers land in a directory the runner creates for it and deletes when it finishes, so a test holds disk only while it runs at any concurrency. The run-shared directory holds the unpacked images every bootstrap clones from, and is removed when the run ends.
A container's storage is its rootfs, an optional writable layer, and its mounts; a machine's is its containers' plus the volumes they share. One generic shape describes both the Mount values a machine is configured with and the AttachedFilesystem values it reports once attached, so converting between the two is a map over the structure and the roles cannot drift between configuration and attachment. Device addresses are allocated walking the same sorted order the devices are created in, on both backends. Consumers read roles instead of list positions: the spec builders take a container's mounts without prefix arithmetic, pod volumes mount by name, and a cloud-hypervisor volume's virtiofsd is held by a machine-lifetime reference alongside its containers' reference counts.
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Summary
A container's storage is its rootfs, an optional writable layer, and its mounts; a machine's is its containers' plus the volumes they share. One generic shape describes both the
Mountvalues a machine is configured with and theAttachedFilesystemvalues it reports once attached, so converting between the two is a map over the structure and the roles cannot drift between configuration and attachment.Device addresses are allocated walking the same sorted order the devices are created in, on both backends. Consumers read roles instead of list positions: the spec builders take a container's mounts without prefix arithmetic, pod volumes mount by name, and a cloud-hypervisor volume's virtiofsd is held by a machine-lifetime reference alongside its containers' reference counts.
Each integration test also runs in a scratch directory the runner creates for it and deletes when it finishes, so a test holds disk only while it runs, at any concurrency. The run-shared directory holds the unpacked images every bootstrap clones from, and goes when the run ends.
Dependency and Merge Order
This targets stock
apple/containerization:mainand depends on #863. Please merge #863 first.The head carries #863's three commits as prerequisites, because both PRs target stock
mainand a fork PR can only base on a branch in this repository. After #863 merges, this branch takes currentmainand its remaining diff is the storage shape and the per-test scratch directory.Motivation and Context
The thing this replaces is positional: attachments were correlated with their configuration by index, so "the first entry is the rootfs, the second is the writable layer if there is one" was knowledge each consumer had to hold and keep in step. Prefix arithmetic like that is invisible when it breaks, and it breaks by someone inserting an attachment.
Giving the two representations one shape means the roles are named in both, and converting is a map rather than a re-derivation. It is what makes #861 (the virtiofs tag collision) expressible as "the additional mounts" rather than "everything after the leading entries".
Testing
swift buildandmake checkclean.swift test: 603 tests in 83 suites passed.Type of Change