The previous method was a "throw it in the sea"-type migration with some
(very arbitrary) sleep statements thrown in for good measure.
Reimplement this with some hard locking. During each phase of the
transition, the nodes acquire read/write shared locks to a Zookeeper key
so that they can tightly coordinate the actions of transferring each
part of the primary state between them. This is done in a subthread to
prevent strange blocking issues that were encountered, likely due to
business in the existing main thread.
Implements the storing of three VM metadata attributes:
1. Node limits - allows specifying a list of hosts on which the VM must
run. This limit influences the migration behaviour of VMs.
2. Per-VM node selectors - allows each VM to have its migration
autoselection method specified, to automatically allow different methods
per VM based on the administrator's preferences.
3. VM autorestart - allows a VM to be automatically restarted from a
stopped state, presumably due to a failure to find a target node (either
due to limits or otherwise) during a flush/fence recovery, on the next
node unflush/ready state of its home hypervisor. Useful mostly in
conjunction with limits to ensure that VMs which were shut down due to
there being no valid migration targets are started back up when their
node becomes ready again.
Includes the full client interaction with these metadata options,
including printing, as well as defining a new function to modify this
metadata. For the CLI it is set/modified either on `vm define` or via the
`vm meta` command. For the API it is set/modified either on a POST to
the `/vm` endpoint (during VM definition) or on POST to the `/vm/<vm>`
endpoint. For the API this replaces the previous reserved word for VM
creation from scratch as this will no longer be implemented in-daemon
(see #22).
Closes#52
Adds some logic to allow an active shutdown state to be aborted by
changing the VM to another state. Useful mostly if a VM is doing funky
things and not responding to the shutdown, but the administrator either
doesn't want to wait for the timer to expire (forcing an immediate
termination) or wishes to abort the shutdown attempt.
Fixes#49
listen-address is enough; adding interface too causes weird issues where
dnsmasq is listening on an IPv6 global wildcard too which conflicts with
the PowerDNS instance.
Includes a simple implementation of a zookeeper "rename" facility,
allowing a key and all data to be replaced by a new key with a different
name but containing all the same child elements and data.
[2/2] Implements #44
Store the flush_thread of a node as a class object. Before starting a
new flush thread (either flush or unflush), stop the existing one if it
exists to prevent further migrations, then start the new thread. Set the
object to None on init and again once the task actually finishes. Remove
the inflush flag as this is not required when using these threads and
functionally does nothing any longer, but add the flush_stopper flag to
trigger cancellation of the current job.
This just seemed like more trouble that it was worth. Flush locks were
originally intended as a way to counteract the weird issues around
flushing that were mostly fixed by the code refactoring, so this will
help test if those issues are truly gone. If not, will look into a
cleaner solution that doesn't result in unchangeable states.
Without this, the IPMI information set during initial node creation can
never be changed, which can cause issues later. Instead, always set it
fresh on each node boot.
Similar to recent client changes, don't replace the previous node record
of an already-migrated VM. Wait for shutdown if required. Use a
continue statement instead of a needless else block.
Adds a config flag that turns on the API client following the Primary
coordinator. The retcode of the start/stop commands is ignore so this
can fail gracefully if e.g. the client isn't installed.
This was very old code that was hard to follow and quite fragile, with
failures and infinite loops occurring fairly frequently. These changes
make the code more robust, including the addition of timeouts, some code
cleanup, and some improvements to the logical flow.
Also forces the libvirt migration to occur on the cluster network, which
couples to changes in the libvirtd listen (via pvc-ansible) and in
Daemon.py via the previous commit.
Reference: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=717215#68
Without this, DHCP fails when traversing only the local bridge, for
Debian Jessie or earlier (and possibly other OSes as well), due to the
missing UDP checksums. This disables the offload and hence reenables
the checksums even on the software-only bridge.
Also rearranged the steps and added comments arround this section to
better clarify what each command is doing.
There was really no need for this to be shared among all the
coordinators, which seemed more fragile. This way only the primary will
try to fence dead nodes.
Joshua Boniface