Let a service manager run as a container's init - #866
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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.
An image built around a service manager expects to own the runtime state it keeps, and finds nowhere to write it: a container gets its image's filesystem and the mounts a single process needs, so the manager cannot start and takes the container down with it. Give it somewhere to write, which is what nerdctl and podman give such a container, and take the same paths to mean one is being asked for. The container says which of the three it wants: never, whenever the process it starts is a service manager, or whatever it starts. Never is the default, as it is for the runtimes that create cgroups themselves. A mount the caller supplied for one of those places is left as they asked for it, and a pod's containers ask the same way.
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Summary
An image built around a service manager expects to own the runtime state it keeps, and finds nowhere to write it: a container gets its image's filesystem and the mounts a single process needs, so the manager cannot start and takes the container down with it.
Give it somewhere to write, which is what podman gives such a container, and take the same paths to mean one is being asked for. The container says which of the three it wants: never, whenever the process it starts is a service manager, or whatever it starts. Never is the default, as it is for the runtimes that create cgroups themselves.
A mount the caller supplied for one of those places is left as they asked for it, and a pod's containers ask the same way.
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
main. After #863 merges this branch can take currentmain, leaving only the systemd-mode change and its test.The dependency is real rather than incidental: a systemd container needs
nf_tablesin the guest, and #863 is what makes the suite run against the kernel release the shipped tool installs rather than an older one built without it.Motivation and Context
The journal directory here is
/var/log/journal, which is wheresystemd-journaldwrites persistent logs, with volatile logs going to/run/log/journal:https://www.freedesktop.org/software/systemd/man/latest/journald.conf.html
Worth noting for reviewers comparing against other runtimes: nerdctl's list names
/var/lib/journal, which journald does not consult, so a container given that one has a tmpfs nothing writes to. podman uses/var/log/journal. This follows podman.Testing
swift buildandmake checkclean.swift test: 603 tests in 83 suites passed.container systemdboots a systemd image as init and asserts both that PID 1 is systemd and that it reaches a running or degraded state, rather than dying at start.Type of Change