Rather than using a cumbersome and overly complex ping-pong of read and
write locks, instead move to a much simpler process using exclusive
locks.
Describing the process in ASCII or narrative is cumbersome, but the
process ping-pongs via a set of exclusive locks and wait timers, so that
the two sides are able to synchronize via blocking the exclusive lock.
The end result is a much more streamlined migration (takes about half
the time all things considered) which should be less error-prone.
1. Output from ipmitool was not being stripped, and stray newlines were
throwing off the comparisons. Fixes this.
2. Several stages were lacking meaningful messages. Adds these in so the
output is more clear about what is going on.
3. Reduce the sleep time after a fence to just 1x the
keepalive_interval, rather than 2x, because this seemed like excessively
long even for slow IPMI interfaces, especially since we're checking the
power state now anyways.
4. Set the node daemon state to an explicit 'fenced' state after a
successful fence to indicate to users that the node was indeed fenced
successfully and not still 'dead'.
The previous implementation did not work with /dev/nvme devices or any
/dev/disk/by-* devices due to some logical failures in the partition
naming scheme, so fix these, and be explicit about what is supported in
the PVC CLI command output.
The 'echo | gdisk' implementation of partition creation also did not
work due to limitations of subprocess.run; instead, use sgdisk which
allows these commands to be written out explicitly and is included in
the same package as gdisk.
The default of 0.05 (5%) is likely ideal in the initial implementation,
but allow this to be set explicitly for maximum flexibility in
space-constrained or performance-critical use-cases.
Adds in three parts:
1. Create an API endpoint to create OSD DB volume groups on a device.
Passed through to the node via the same command pipeline as
creating/removing OSDs, and creates a volume group with a fixed name
(osd-db).
2. Adds API support for specifying whether or not to use this DB volume
group when creating a new OSD via the "ext_db" flag. Naming and sizing
is fixed for simplicity and based on Ceph recommendations (5% of OSD
size). The Zookeeper schema tracks the block device to use during
removal.
3. Adds CLI support for the new and modified API endpoints, as well as
displaying the block device and DB block device in the OSD list.
While I debated supporting adding a DB device to an existing OSD, in
practice this ended up being a very complex operation involving stopping
the OSD and setting some options, so this is not supported; this can be
specified during OSD creation only.
Closes#142
Adds a new API endpoint to support hot attach/detach of devices, and the
corresponding client-side logic to use this endpoint when doing VM
network/storage add/remove actions.
The live attach is now the default behaviour for these types of
additions and removals, and can be disabled if needed.
Closes#141
This branch commit refactors the pvcnoded component to better adhere to
good programming practices. The previous Daemon.py was a massive file
which contained almost 2000 lines of direct, root-level code which was
directly imported. Not only was this poor practice, but this resulted
in a nigh-unmaintainable file which was hard even for me to understand.
This refactoring splits a large section of the code from Daemon.py into
separate small modules and functions in the `util/` directory. This will
hopefully make most of the functionality easy to find and modify without
having to dig through a single large file.
Further the existing subcomponents have been moved to the `objects/`
directory which clearly separates them.
Finally, the Daemon.py code has mostly been moved into a function,
`entrypoint()`, which is then called from the `pvcnoded.py` stub.
An additional item is that most format strings have been replaced by
f-strings to make use of the Python 3.6 features in Daemon.py and the
utility files.
We need to do a bit more finagling with the logger on termination to
ensure that all messages are written and the queue drained before
actually terminating.
Adds the ability to send node daemon logs to Zookeeper to facilitate a
command like "pvc node log", similar to "pvc vm log". Each node stores
its logs in a separate tree under "/logs" which can then be combined or
queried. By default, set by config, only 2000 lines are kept.
Previously, if the node failed to restart, it was declared a "bad fence"
and no further action would be taken. However, there are some
situations, for instance critical hardware failures, where intelligent
systems will not attempt (or succeed at) starting up the node in such a
case, which would result in dead, known-offline nodes without recovery.
Tweak this behaviour somewhat. The main path of Reboot -> Check On ->
Success + fence-flush is retained, but some additional side-paths are
now defined:
1. We attempt to power "on" the chassis 1 second after the reboot, just
in case it is off and can be recovered. We then wait another 2 seconds
and check the power status (as we did before).
2. If the reboot succeeded, follow this series of choices:
a. If the chassis is on, the fence succeeded.
b. If the chassis is off, the fence "succeeded" as well.
c. If the chassis is in some other state, the fence failed.
3. If the reboot failed, follow this series of choices:
a. If the chassis is off, the fence itself failed, but we can treat
it as "succeeded"" since the chassis is in a known-offline state.
This is the most likely situation when there is a critical hardware
failure, and the server's IPMI does not allow itself to start back
up again.
b. If the chassis is in any other state ("on" or unknown), the fence
itself failed and we must treat this as a fence failure.
Overall, this should alleviate the aforementioned issue of a critical
failure rendering the node persistently "off" not triggering a
fence-flush and ensure fencing is more robust.
Joshua Boniface