Using the Rados module was very problematic, specifically because it had
no sensible timeout parameters and thus would hang for many seconds.
This has poor implications since it blocks further keepalives.
Instead, remove the Rados usage entirely and go back completely to using
manual OS commands to gather this information. While this may cause PID
exhaustion more quickly it's worthwhile to avoid failure scenarios when
Ceph stats time out.
Closes#137
Not sure how this didn't cause an issue until now, but the wrong key
path was used and this was getting unexpected data with the newly-added
version string instead of the proper mode string.
When doing a stop_vm or terminate_vm, check again after 0.2 seconds
and try re-terminating if it's still running. Covers cases where a VM
doesn't stop if given the 'stop' state.
Trying to do this on the VMInstance side had problems because we can't
differentiate the 3 types of migration there. So, just update this in
the API side and hope everything goes well.
This introduces an edge bug: if a VM is using a macvtap SR-IOV device,
and then tries to migrate, and the migrate is aborted, the NIC lists
will be inconsistent.
When I revamp the VMInstance in the future, I should be able to correct
this, but for now we'll have to live with that edgecase.
Ensures that the configuration of a VF is not overwritten in Zookeeper
on a node restart. The SRIOVVFInstance handlers were modified to start
with None values, so that the DataWatch statements will always trigger
updates to the live system interfaces on daemon startup, thus ensuring
that the config stored in Zookeeper is applied to the system on startup
(mostly relevant after a cold boot or if the API changes them during a
daemon restart).
Adds support for the node daemon managing SR-IOV PF and VF instances.
PFs are added to Zookeeper automatically based on the config at startup
during network configuration, and are otherwise completely static. PFs
are automatically removed from Zookeeper, along with all coresponding
VFs, should the PF phy device be removed from the configuration.
VFs are configured based on the (autocreated) VFs of each PF device,
added to Zookeeper, and then a new class instance, SRIOVVFInstance, is
used to watch them for configuration changes. This will enable the
runtime management of VF settings by the API. The set of keys ensures
that both configuration and details of the NIC can be tracked.
Most keys are self-explanatory, especially for PFs and the basic keys
for VFs. The configuration tree is also self-explanatory, being based
entirely on the options available in the `ip link set {dev} vf` command.
Two additional keys are also present: `used` and `used_by`, which will
be able to track the (boolean) state of usage, as well as the VM that
uses a given VIF. Since the VM side implementation will support both
macvtap and direct "hostdev" assignments, this will ensure that this
state can be tracked on both the VF and the VM side.
Adds configuration values for enabled flag and SR-IOV devices to the
configuration and sets up the initial SR-IOV configuration on daemon
startup (inserting the module, configuring the VF count, etc.).
Instead of exiting and trusting systemd to restart us, instead leverage
the os.execv() call to reload the process in the current PID context.
Also improves the log messages so it's very clear what's going on.
A hot reload isn't possible due to DataWatch and ChildrenWatch
constructs, so we instead need to terminate the daemon to "apply" the
schema update. Thus we use exit code 150 (Application defined in LSB)
and reorder some of the elements of the schema validation to ensure
things happen in the right order.
Found a rare glitch where the subprocess pipes would not engage, causing
a daemon crash. Catch these exceptions with a retcode of 255 instead of
bailing out.
Closes#124
Libvirt will someones write junk out to console log files, which breaks
the log parser deque with a UnicodeDecodeError.
If this happens, clear the log and re-open the deque again for newer
updates.
Closes#123
Add nicer easy-to-find (yay ASCII art) banners for the startup printouts
of both the node and API daemons. Also adds the safe loader to pvcnoded
to prevent hassle messages and a version string in the API daemon file.
Sets in the node daemon, returns via the API, and shows in the CLI,
information about the live VNC listen address and port for VNC-enabled
VMs.
Closes#115
Prevents unnecessarily excessive timeouts if IPMI connections time out;
before, would have to go through 3 timed out commands at ~20s each
before failure was registered; reduced to 1 if the first times out.
If the VM is not in a stop state, failing to free the lock is now
considered a fatal error and will put the domain into fail state,
aborting the start. This is better than being unsafe or trying to start
a VM which will fail to boot due to read-only volumes.
Should correct issues on cold start as well as if a VM crashes
uncleanly, which would prevent the VM from starting due to stale RBD
locks.
This implementation has four parts:
1. Update how IP addresses are handled, specifically by replacing all
previous instances of "vni_ipaddr" with "vni_floatingipaddr", and then
adding the "vni_ipaddr" with the real data for this node's IPs. Also
include the storage IPs in this where they weren't before, so each
this_node actually has the local IPs plus floating IPs. This enables
the next two steps.
2. Modify flush_locks to take this_node as an argument, and update the
run_command function to only operate against this node, rather than on
the primary coordinator.
3. Have the flush_locks check each lock against the current node, to
verify that the lock is actually held by the current node. This is the
only way to do this safely. During fencing, we override this by not
passing a this_node which bypasses this check.
4. Have the VM start do the check for VM failure/startup and execute a
flush_locks before actually starting the VM.
Instead of each node uploading its own OSD stats, which would not work
if the PVC daemon wasn't running, instead have the primary upload stats
for all OSDs in the cluster.
Allow a VM to specify its migration type as a default choice. The valid
options are "default" (i.e. behave as now), "live" which forces a live
migration only, and "shutdown" which forces a shutdown migration only.
The new option is treated as a VM meta option and is set to default if
not found.
Avoids situations where two migrates, to different nodes, happen in
rapid succession. Aborts the migration if the current target node no
longer matches what was set at the start of the execution.
The VM migration code was very old, very spaghettified, and prone to
strange failures.
Improve this by taking cues from the node primary migration. Use
synchronization between the nodes to ensure lockstep completion of the
migration in discrete steps.
A proper queue can be built later to integrate with this code more
cleanly.
References #108
Use the new "provisioned" memory field, instead of the "allocated"
memory field, to determine the optimal node when using the "mem"
migration selector. This will take into account non-running VMs in the
calculation as well as running VMs.
Adds a separate field to the node memory, "provisioned", which totals
the amount of memory provisioned to all VMs on the node, regardless of
state, and in contrast to "allocated" which only counts running VMs.
Allows for the detection of potential overprovisioned states when
factoring in non-running VMs.
Includes the supporting code to get this data, since the original
implementation of VM memory selection was dependent on the VM being
running and getting this from libvirt. Now, if the VM is not active, it
gets this from the domain XML instead.
Prevents any potential leakage due to autoconfigured IPv6 on bridged
interfaces. These are exclusively VM-side bridges, and the PVC host
should not have any IPv6 configuration on them, ever.
Prevents a bug where the thread can crash due to a change in the
d_domain object while running the for loop. By copying and iterating
over the copy, this becomes safer.
The keepalive was getting stuck gathering memoryStats from the
non-running VM, since it was in a paused state. Avoid this by just
skipping past the rest of the stats gathering if the VM isn't running.
Most of these would silently fail if there was e.g. an issue with the ZK
connection. Instead, encase things in try blocks and handle the
exceptions in a more graceful way, returning None or False if
applicable. Except for locks, which should retry 5 times before
aborting.
Using simple print statements was annoying (lack of timing info and
formatting), so move to using the debug logger for these instead with a
custom state ('d') with white text to differentiate them. Also indicate
which subthread of the keepalive each task is being executed in for
easier tracing of issues.
Verify our IPMI state on startup, and then warn if fencing will fail.
For now, this is sufficient, but in future (requires refactoring) we
might want to adjust how fencing occurs based on this information.
Using the Ceph library was a disaster here; it had no timeout or way to
force it to continue, so keepalives would become stuck and trigger fence
storms. Go back to the manual osd dump command with a 2s timeout which
is far more reliable and can be adequately terminated if it runs long.
Prevent the main keepalive thread from getting stuck due to a subthread
taking an enormous time. If this happens, the rest of the main keepalive
will continue onward, thus ensuring that the main keepalive does not
fail for a significant number of cycles, which would cause a fence.
The previous saving throw limit (3/15s) seems to have been too low. I
was observing bizarre failures where a node would be fenced while it was
still starting up. Some of this may have been related to Zookeeper
connections taking too long, but this was inconsistent.
Increase this to 6 saving throws (30s). This provides significantly more
time for a node to properly check in on startup before another node
fences it. In the real world, 15s vs 30s isn't that big of a downtime
change, but prevents false-positive fences.
Provides a CLI and API argument to force live migration, which triggers
a new VM state "migrate-live". The node daemon VMInstance during migrate
will read this flag from the state and, if enforced, will not trigger a
shutdown migration.
Closes#95
Prevents a rare edge case where a node can end up "migrating" to itself.
Quick hack to fix this, though like most of the VM management should
probably be rethought/rewritten later.
Fixes#92
Make sure the stopping of the keepalive timer and final keepalive update
are done as the last step before complete shutdown. The previous setup
could conceivably result in a node being fenced should the cleanup
operations take longer than ~45 seconds, for instance if primary node
switchover took too long or blocked, or log watchers failed to stop
quickly enough. Ensures that keepalives will continue to be run during
the shutdown process until the last possible moment.
Previously, contention could occasionally cause a flap/dual primary
contention state due to the lack of checking within this function. This
could cause a state where a node transitions to primary than is almost
immediately shifted away, which could cause undefined behaviour in the
cluster.
The solution includes several elements:
* Implement an exclusive lock operation in zkhandler
* Switch the become_primary function to use this exclusive lock
* Implement exclusive locking during the contention process
* As a failsafe, check stat versions before setting the node as the
primary node, in case another node already has
* Delay the start of takeover/relinquish operations by slightly
longer than the lock timeout
* Make the current router_state conditions more explicit (positive
conditionals rather than negative conditionals)
The new scenario ensures that during contention, only one secondary will
ever succeed at acquiring the lock. Ideally, the other would then grab
the lock and pass, but in testing this does not seem to be the case -
the lock always times out, so the failsafe check is technically not
needed but has been left as an added safety mechanism. With this setup,
the node that fails the contention will never block the switchover nor
will it try to force itself onto the cluster after another node has
successfully won contention.
Timeouts may need to be adjusted in the future, but the base timeout of
0.4 seconds (and transition delay of 0.5 seconds) seems to work reliably
during preliminary tests.
Most of these actions/conditionals were looking for primary state, but
were failing during node takeover. Update the conditionals to look for
both router states instead.
Also add a wait to lock flushing until a takeover is completed.
Use a pair of transitional states, "takeover" and "relinquish", when
transitioning between primary and secondary coordinator states. This
provides a clsuter-wide record that the nodes are still working during
their synchronous transition states, and should allow clients to
determine when the node(s) have fully switched over. Also add an
additional 2 seconds of wait at the end of the transition jobs to ensure
everything has had a chance to start before proceeding.
References #72
Rename "pvcd" to "pvcnoded", and "pvc-api" to "pvcapid" so names for the
daemons are fully consistent. Update the names of the configuration
files as well to match this new formatting.
References #79
Joshua Boniface