The `nomad volume deregister` command currently returns an error if the volume
has any claims, but in cases where the claims can't be dropped because of
plugin errors, providing a `-force` flag gives the operator an escape hatch.
If the volume has no allocations or if they are all terminal, this flag
deletes the volume from the state store, immediately and implicitly dropping
all claims without further CSI RPCs. Note that this will not also
unmount/detach the volume, which we'll make the responsibility of a separate
`nomad volume detach` command.
The volumewatcher restores itself on notification, but detecting this is racy
because it may reap any claim (or find there are no claims to reap) and
shutdown before we can test whether it's running. This appears to have become
flaky with a new version of golang. The other cases in this test case
sufficiently exercise the start/stop behavior of the volumewatcher, so remove
the flaky section.
CSI plugins can require credentials for some publishing and
unpublishing workflow RPCs. Secrets are configured at the time of
volume registration, stored in the volume struct, and then passed
around as an opaque map by Nomad to the plugins.
The watcher goroutines will be automatically started if a volume has
updates, but when idle we shouldn't keep a goroutine running and
taking up memory.
The `volumewatcher` has a 250ms batch window so claim updates will not
typically be large enough to risk exceeding the maximum raft message
size. But large jobs might have enough volume claims that this could
be a danger. Set a maximum batch size of 100 messages per
batch (roughly 33K), as a very conservative safety/robustness guard.
Co-authored-by: Chris Baker <1675087+cgbaker@users.noreply.github.com>
* volumewatcher: remove redundant log fields
The constructor for `volumeWatcher` already sets a `logger.With` that
includes the volume ID and namespace fields. Remove them from the
various trace logs.
* volumewatcher: advance state for controller already released
One way of bypassing client RPCs in testing is to set a claim status
to controller-detached, but this results in an incorrect claim state
when we checkpoint.
The nil-check here is left-over from an earlier approach that didn't
get merged. It doesn't do anything for us now as we can't ever pass it
`nil` and if we leave it in the `getVolume` call it guards will panic
anyways.
We should only remove the `ReadAllocs`/`WriteAllocs` values for a
volume after the claim has entered the "ready to free"
state. The volume will eventually be released as expected. But
querying the volume API will show the volume is released before the
controller unpublish has finished and this can cause a race with
starting new jobs.
Test updates are to cover cases where we're dropping claims but not
running through the whole reaping process.
This changeset adds a subsystem to run on the leader, similar to the
deployment watcher or node drainer. The `Watcher` performs a blocking
query on updates to the `CSIVolumes` table and triggers reaping of
volume claims.
This will avoid tying up scheduling workers by immediately sending
volume claim workloads into their own loop, rather than blocking the
scheduling workers in the core GC job doing things like talking to CSI
controllers
The volume watcher is enabled on leader step-up and disabled on leader
step-down.
The volume claim GC mechanism now makes an empty claim RPC for the
volume to trigger an index bump. That in turn unblocks the blocking
query in the volume watcher so it can assess which claims can be
released for a volume.
