Destroying a VM with its disk files forced it off first and then
worked out which files to delete, so a check that failed left the VM
stopped, and only this host's VMs and volumes were checked: a file on
shared storage that a VM on another host uses was deleted.
The files are now worked out before the VM is stopped: the disks it
runs with and those of its next start, as before with their snapshot
files and seed. A file a VM or volume of another of the panel's hosts
uses at the same path (shared storage is mounted at one path on every
host, as migration needs) is kept like one used here; another record
of the VM's own host is skipped, as there the VM itself uses them. A
host that cannot be read stops the destruction with its name, before
anything is stopped or deleted.
The Destroy tab was a sub-tab with one sentence and a link; its
confirmation page said only "This action is irreversible!" over a
"Remove Instance's data" switch. The tab now shows the state and
"Review destruction". The owner chose the confirmation layout from
three rendered options: the VM and its host, that its definition,
saved state and snapshot records go and that a running VM is forced
off, two plans for the files (delete the disk files, or keep them), the
VM's disks, what is always kept, the NVRAM choice, and Cancel.
Codex reviewed destroying; this is fixed:
- A disk file that cannot be deleted keeps the files below it, which
it needs: they were deleted after it, leaving it broken. The files
are deleted overlays first (split_disk_paths_by_use orders them by
how many files each grows from), and if the files a kept one needs
cannot be read, none of the rest goes. A message names each file
kept so, and a failed deletion says the VM is removed.
The Snapshots tab had three sub-tabs: internal, external and the
lists, with the two kinds side by side as equals. The owner set the
direction: external snapshots are the way; internal ones pause the VM
while its memory is saved and can take long, so they stay only as a
fallback for a VM that cannot take an external one.
The tab now has the external snapshot form on top, its name and
description on one line, with its memory and freeze options; the
internal snapshot under a folded "fallback" line with its warning; and
one list of all snapshots, newest first, each on one line with its
name, description, kind and date, and Revert and Delete.
Codex reviewed snapshots end to end; these are fixed:
- The pause and memory lines follow the VM's state and the kind.
- An internal snapshot is reverted to on a shut-off VM only, on the
server too; the tab alone held that rule.
- A paused VM's revert says it comes back paused, not that it starts.
- An external snapshot waits, with the reason, while snapshots newer
than the one reverted to exist; the server refused it unexplained.
- Deleting an external snapshot says its files are merged with the
disks; "into the next one" was wrong for the last one.
- The description has no 45-character limit only the browser kept.
- Freezing is not shown ticked where it cannot be offered, and
unticking memory gives back the earlier freeze choice.
- Internal create, revert and delete refuse a saved state or a running
disk job, as external ones do.
Cloud images read their first-boot settings with cloud-init. The panel
served them only over HTTP, which a VM reaches only with the network
and a reverse DNS name for its address. A new VM can now carry them
itself: Cloud-init seed (Advanced) on the create form, or cloud_init in
the API.
The job writes a NoCloud seed, an ISO labelled cidata, into the disk's
directory pool as cidata-<uuid>.iso and puts it in the VM's CD-ROM
drive. Its meta-data holds the VM's UUID as instance-id and its name as
hostname, written as JSON so a VM named 123 or yes keeps a string
hostname; its user-data is what the HTTP datasource serves, with the
creating user's SSH keys. The ISO is built with pycdlib and written
through a libvirt stream, as the NVRAM copy is, now one helper for both.
A seed needs a CD-ROM bus and a directory pool, else the create is
refused. A failed create deletes the seed with the new disk, recovery
names one left behind, and deleting the VM with its disks deletes its
seed, found in the pools by name even when ejected. A clone's drive is
left empty: the seed is the source VM's identity.
A quiesced snapshot and a live clone freeze the guest's file systems
through libvirt, which asks the agent without a timeout: with the agent
hung, the job waited, holding the VM, with no end.
The agent must now first answer a guest-ping within 10 s; a frozen or
dead agent fails the job in seconds, before anything is frozen. The
freeze itself stays libvirt's, without a timeout: a timed freeze was
tried and left the guest frozen, since the freeze still ran in the
guest when the agent came back, after its thaw had failed.
A disk-only snapshot was taken without any space check, though its
overlays grow as the guest writes and a later delete merges them down;
a full pool pauses the guest and can leave the snapshot undeletable.
Only a memory snapshot was checked, for the memory alone.
Before a snapshot, each storage pool with a disk of the VM must have
free a share of those disks' virtual size (10%, at least 1 GiB), and
the pool of the memory file the VM's memory on top. Both values are on
the Settings page (Snapshot Free Percent, Snapshot Free Min GiB; 0
turns a rule off, an invalid value keeps the default). The pools are
refreshed first, and a failed refresh or an unreadable volume refuses
the snapshot instead of skipping the check; a disk in no pool is not
checked. Nothing is reserved: later writes can still fill a pool.
A disk-only snapshot of a running VM is crash-consistent: data the
guest has not written yet is missing from it. With a connected QEMU
guest agent, the snapshot form now offers to freeze the guest's file
systems while the disks are snapshotted (libvirt's QUIESCE flag); the
box is checked by default and can be cleared. It is offered only for a
running VM whose agent is connected, and not together with memory:
libvirt accepts quiesce only for disk-only snapshots, and a memory
snapshot keeps the whole guest state anyway. A request that does not
fit is refused before libvirt is called.
After a snapshot revert or delete, files libvirt could not remove are
named in a warning that says nothing uses them and asks to remove them
by hand. A file another VM on the same host uses (as a disk, a backing
file or a snapshot file) is no longer named: removing it would break
that VM. The warning now says no VM on this host uses the files.
Deleting a VM with its data deleted only the images its disks pointed
at. With external snapshots that is the newest overlay: the image the
snapshots were taken on, the older overlays and the memory files stayed
on disk, with nothing referring to them once the VM and its snapshot
metadata were gone.
The files the VM's snapshots were taken on, down each disk's backing
chain, the overlays of snapshots kept off the chain after a revert, and
the snapshots' memory files are now the VM's own too. A template the
VM grew from ends the chain and stays, as does an overlay of a disk
detached since. The backing references of the VM's own volumes no
longer count as another domain's use, and a file another VM uses keeps
the files below it.
A backing file that cannot be read (other than one in no pool) stops the
split before anything is deleted, instead of ending the chain there.
The snapshot tab listed the VM's snapshots three times per page: once
per kind and once more for all of them. The list of all is now made
from the two kinds, so the combined flag is no longer used anywhere.
The revert confirm named only the disks the persistent definition
would lose. A disk hot-plugged into the running VM alone is detached
too, so the live definition is compared with what ran when the
snapshot was taken.
A storage pool refresh error after libvirt had already made, reverted
or deleted the snapshot was shown as if the operation had failed. It
is now logged, and the left-behind check is skipped then, since a stale
pool still lists the removed files. A volume removed while that check
reads it is skipped too.
An error reading the block jobs no longer breaks the instance page;
create, revert and delete still query the jobs again and refuse.
When libvirt cannot remove a snapshot file it merged or discarded, it
only logs a warning and the delete or revert still succeeds. On NFS it
removes them as the qemu user, so an image directory the qemu user may
not write to left every merged overlay on disk without a word.
Revert and delete now compare the files in use before and after and
show a warning naming the ones still on disk. Only a snapshot's own
files (overlays, memory) and overlays on a snapshot point count, and a
disk the revert detached is never named, so a kept disk is not offered
for removal.
Create, revert and delete are one libvirt call each. The pflash-to-rom
loader rewrite, the hand-written block commit and the s1./s2. names are
gone, so UEFI VMs can take external snapshots, a revert keeps disks added
later, and deleting an older snapshot keeps the newer one.
Create refuses what libvirt could not revert or delete later: internal
snapshots on the VM, a saved state, a running snapshot job, disks that
are not files, CD-ROM media, a branch after a revert, and memory without
a running VM or room in the first disk's pool. A disk-only revert keeps
the VM running, paused or shut off; one with memory resumes it as saved.
A revert in the same second as the previous one, which libvirt fails
after stopping the VM, is retried once.
A snapshot the old code took of a UEFI VM saved the loader as rom; its
revert is refused (deleting it still works).
The snapshots tab lists internal and external snapshots separately, can
save memory too, shows running snapshot jobs, and the revert confirmation
names the disks it detaches and that NVRAM is not restored.
