What migrate_instance did around the migration itself:
- It checked the destination with a 1 s TCP probe of the libvirt port,
which passes while libvirt is down or refuses the login. It now uses
the compute's connection status, as the rest of the app does.
- Two requests for the same VM waited for the compute locks one after
the other; the second then migrated with the VM's old location. The
VM's record is read again under the locks, and the request is
refused when the VM is no longer on the source.
- Restoring autostart on the destination came after the migration but
before the database move; when it failed, the VM ran on the
destination while the app recorded it on the source. Autostart is
now read from libvirt and a failure to restore it is only logged.
- A database failure after a successful migration was logged as
nothing; the log now says the VM migrated and recording it failed.
- When the destination's list had already made a record for the VM,
the merge kept the owners but dropped the template mark.
The VM page reads the VM from libvirt throughout. When its host could
not be reached, the connection error replaced the page with the error
page and showed libvirt's message, which names the host and how it is
reached, to any user who may view the VM.
The page now checks Compute.status first. If the host is not connected,
it goes to the instance list with a message: administrators (superuser
or view_instances) get the host and the error, other users only that
the VM's host cannot be reached right now. The list shows the VM as
unknown.
This covers the page itself; actions on the VM still report libvirt's
error if the host drops. The detail page tests now mock a connected
host.
Checked against the test hosts: a real VM's page opens as before, a VM
on an unreachable compute leads to the list with the user's or the
administrator's message. The new tests fail on the previous code.
check_user_quota added up the vCPUs, memory and disks of the user's
VMs, but skipped a VM whose host failed a TCP probe. A host that was
down therefore let users exceed their quota, and the probe always failed
for ssh computes named by an ssh_config alias or reached through
ProxyJump, so their VMs were never counted. A VM that could not be read
turned the page into the error page instead.
- Hosts are checked with Compute.status, the connection WebVirtCloud
uses, once per host. A VM that cannot be read (host down, VM gone)
makes the usage unknown: clone and resize up are refused with their
own message (fail closed).
- A request that adds nothing is not checked, so a user over quota can
still shrink a VM. Users without limits, and an exceeded instance
count (from the database), need no host either.
- Memory resize of a running VM changes only the current memory, but
the quota was charged with the submitted maximum. It is now charged
with no change, and resize_mem gets the current maximum, so a VM that
shuts down meanwhile cannot take an unchecked one.
- The VM page no longer computes the quota on every load (it read every
VM of the user on every host for a "quota reached" banner). The limit
is reported when a change is refused.
The test that expected a down host to pass the quota now expects it to
be refused. Checked against the test hosts: with a VM behind an
ssh_config alias the previous code counted 29 vCPUs, the new one 31;
with a VM on an unreachable host the previous code allowed +1 vCPU,
the new one refuses it after 5.1 s and allows -1 at once. The new
tests fail on the previous code, except the ones guarding unchanged
behaviour.
