This changeset implements a periodic garbage collection of CSI volumes
with missing allocations. This can happen in a scenario where a node
update fails partially and the allocation updates are written to raft
but the evaluations to GC the volumes are dropped. This feature will
cover this edge case and ensure that upgrades from 0.11.0 and 0.11.1
get any stray claims cleaned up.
This changeset implements a periodic garbage collection of unused CSI
plugins. Plugins are self-cleaning when the last allocation for a
plugin is stopped, but this feature will cover any missing edge cases
and ensure that upgrades from 0.11.0 and 0.11.1 get any stray plugins
cleaned up.
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.
Adds a `CSIVolumeClaim` type to be tracked as current and past claims
on a volume. Allows for a client RPC failure during node or controller
detachment without having to keep the allocation around after the
first garbage collection eval.
This changeset lays groundwork for moving the actual detachment RPCs
into a volume watching loop outside the GC eval.
The current design of `ClientCSI` RPC requires that callers in the
server know about the free-standing `nodeForControllerPlugin`
function. This makes it difficult to send `ClientCSI` RPC messages
from subpackages of `nomad` and adds a bunch of boilerplate to every
server-side caller of a controller RPC.
This changeset makes it so that the `ClientCSI` RPCs will populate and
validate the controller's client node ID if it hasn't been passed by
the caller, centralizing the logic of picking and validating
controller targets into the `nomad.ClientCSI` struct.
The `Job.Deregister` call will block on the client CSI controller RPCs
while the alloc still exists on the Nomad client node. So we need to
make the volume claim reaping async from the `Job.Deregister`. This
allows `nomad job stop` to return immediately. In order to make this
work, this changeset changes the volume GC so that the GC jobs are on a
by-volume basis rather than a by-job basis; we won't have to query
the (possibly deleted) job at the time of volume GC. We smuggle the
volume ID and whether it's a purge into the GC eval ID the same way we
smuggled the job ID previously.
The CSI plugins uses the external volume ID for all operations, but
the Client CSI RPCs uses the Nomad volume ID (human-friendly) for the
mount paths. Pass the External ID as an arg in the RPC call so that
the unpublish workflows have it without calling back to the server to
find the external ID.
The controller CSI plugins need the CSI node ID (or in other words,
the storage provider's view of node ID like the EC2 instance ID), not
the Nomad node ID, to determine how to detach the external volume.
* nomad/state/state_store: error message copy/paste error
* nomad/structs/structs: add a VolumeEval to the JobDeregisterResponse
* nomad/job_endpoint: synchronously, volumeClaimReap on job Deregister
* nomad/core_sched: make volumeClaimReap available without a CoreSched
* nomad/job_endpoint: Deregister return early if the job is missing
* nomad/job_endpoint_test: job Deregistion is idempotent
* nomad/core_sched: conditionally ignore alloc status in volumeClaimReap
* nomad/job_endpoint: volumeClaimReap all allocations, even running
* nomad/core_sched_test: extra argument to collectClaimsToGCImpl
* nomad/job_endpoint: job deregistration is not idempotent
If a volume-claiming alloc stops and the CSI Node plugin that serves
that alloc's volumes is missing, there's no way for the allocrunner
hook to send the `NodeUnpublish` and `NodeUnstage` RPCs.
This changeset addresses this issue with a redesign of the client-side
for CSI. Rather than unmounting in the alloc runner hook, the alloc
runner hook will simply exit. When the server gets the
`Node.UpdateAlloc` for the terminal allocation that had a volume claim,
it creates a volume claim GC job. This job will made client RPCs to a
new node plugin RPC endpoint, and only once that succeeds, move on to
making the client RPCs to the controller plugin. If the node plugin is
unavailable, the GC job will fail and be requeued.
* nomad/state/schema: use the namespace compound index
* scheduler/scheduler: CSIVolumeByID interface signature namespace
* scheduler/stack: SetJob on CSIVolumeChecker to capture namespace
* scheduler/feasible: pass the captured namespace to CSIVolumeByID
* nomad/state/state_store: use namespace in csi_volume index
* nomad/fsm: pass namespace to CSIVolumeDeregister & Claim
* nomad/core_sched: pass the namespace in volumeClaimReap
* nomad/node_endpoint_test: namespaces in Claim testing
* nomad/csi_endpoint: pass RequestNamespace to state.*
* nomad/csi_endpoint_test: appropriately failed test
* command/alloc_status_test: appropriately failed test
* node_endpoint_test: avoid notTheNamespace for the job
* scheduler/feasible_test: call SetJob to capture the namespace
* nomad/csi_endpoint: ACL check the req namespace, query by namespace
* nomad/state/state_store: remove deregister namespace check
* nomad/state/state_store: remove unused CSIVolumes
* scheduler/feasible: CSIVolumeChecker SetJob -> SetNamespace
* nomad/csi_endpoint: ACL check
* nomad/state/state_store_test: remove call to state.CSIVolumes
* nomad/core_sched_test: job namespace match so claim gc works
When an alloc is marked terminal (and after node unstage/unpublish
have been called), the client syncs the terminal alloc state with the
server via `Node.UpdateAlloc RPC`.
For each job that has a terminal alloc, the `Node.UpdateAlloc` RPC
handler at the server will emit an eval for a new core job to garbage
collect CSI volume claims. When this eval is handled on the core
scheduler, it will call a `volumeReap` method to release the claims
for all terminal allocs on the job.
The volume reap will issue a `ControllerUnpublishVolume` RPC for any
node that has no alloc claiming the volume. Once this returns (or
is skipped), the volume reap will send a new `CSIVolume.Claim` RPC
that releases the volume claim for that allocation in the state store,
making it available for scheduling again.
This same `volumeReap` method will be called from the core job GC,
which gives us a second chance to reclaim volumes during GC if there
were controller RPC failures.
This changeset adds a new core job `CoreJobCSIVolumePublicationGC` to
the leader's loop for scheduling core job evals. Right now this is an
empty method body without even a config file stanza. Later changesets
will implement the logic of volume publication GC.
This PR fixes an edge case where we could GC an allocation that was in a
desired stop state but had not terminated yet. This can be hit if the
client hasn't shutdown the allocation yet or if the allocation is still
shutting down (long kill_timeout).
Fixes https://github.com/hashicorp/nomad/issues/4940
Tim Gross