This change isolates all the code that deals with node selection in the
scheduler into its own package called feasible.
---------
Co-authored-by: Tim Gross <tgross@hashicorp.com>
We introduce an alternative solution to the one presented in #24960 which is
based on the state store and not previous-next allocation tracking in the
reconciler. This new solution reduces cognitive complexity of the scheduler
code at the cost of slightly more boilerplate code, but also opens up new
possibilities in the future, e.g., allowing users to explicitly "un-stick"
volumes with workloads still running.
The diagram below illustrates the new logic:
SetVolumes() upsertAllocsImpl()
sets ns, job +-----------------checks if alloc requests
tg in the scheduler v sticky vols and consults
| +-----------------------+ state. If there is no claim,
| | TaskGroupVolumeClaim: | it creates one.
| | - namespace |
| | - jobID |
| | - tg name |
| | - vol ID |
v | uniquely identify vol |
hasVolumes() +----+------------------+
consults the state | ^
and returns true | | DeleteJobTxn()
if there's a match <-----------+ +---------------removes the claim from
or if there is no the state
previous claim
| | | |
+-----------------------------+ +------------------------------------------------------+
scheduler state store
Static host volumes have a simple readonly toggle, but dynamic host volumes have
a more complex set of capabilities similar to CSI volumes. Update the
feasibility checker to account for these capabilities and volume readiness.
Also fixes a minor bug in the state store where a soft-delete (not yet
implemented) could cause a volume to be marked ready again. This is needed to
support testing the readiness checking in the scheduler.
Ref: https://github.com/hashicorp/nomad/pull/24479
Implement scheduler support for node pool:
* When a scheduler is invoked, we get a set of the ready nodes in the DCs that
are allowed for that job. Extend the filter to include the node pool.
* Ensure that changes to a job's node pool are picked up as destructive
allocation updates.
* Add `NodesInPool` as a metric to all reporting done by the scheduler.
* Add the node-in-pool the filter to the `Node.Register` RPC so that we don't
generate spurious evals for nodes in the wrong pool.
* One-time tokens are not replicated between regions, so we don't want to enforce
that the version check across all of serf, just members in the same region.
* Scheduler: Disconnected clients handling is specific to a single region, so we
don't want to enforce that the version check across all of serf, just members in
the same region.
* Variables: enforce version check in Apply RPC
* Cleans up a bunch of legacy checks.
This changeset is specific to 1.4.x and the changes for previous versions of
Nomad will be manually backported in a separate PR.
* planner: expose ServerMeetsMinimumVersion via Planner interface
* filterByTainted: add flag indicating disconnect support
* allocReconciler: accept and pass disconnect support flag
* tests: update dependent tests
Processing an evaluation is nearly a pure function over the state
snapshot, but we randomly shuffle the nodes. This means that
developers can't take a given state snapshot and pass an evaluation
through it and be guaranteed the same plan results.
But the evaluation ID is already random, so if we use this as the seed
for shuffling the nodes we can greatly reduce the sources of
non-determinism. Unfortunately golang map iteration uses a global
source of randomness and not a goroutine-local one, but arguably
if the scheduler behavior is impacted by this, that's a bug in the
iteration.
This PR implements a new "System Batch" scheduler type. Jobs can
make use of this new scheduler by setting their type to 'sysbatch'.
Like the name implies, sysbatch can be thought of as a hybrid between
system and batch jobs - it is for running short lived jobs intended to
run on every compatible node in the cluster.
As with batch jobs, sysbatch jobs can also be periodic and/or parameterized
dispatch jobs. A sysbatch job is considered complete when it has been run
on all compatible nodes until reaching a terminal state (success or failed
on retries).
Feasibility and preemption are governed the same as with system jobs. In
this PR, the update stanza is not yet supported. The update stanza is sill
limited in functionality for the underlying system scheduler, and is
not useful yet for sysbatch jobs. Further work in #4740 will improve
support for the update stanza and deployments.
Closes#2527
Callers of `CSIVolumeByID` are generally assuming they should receive a single
volume. This potentially results in feasibility checking being performed
against the wrong volume if a volume's ID is a prefix substring of other
volume (for example: "test" and "testing").
Removing the incorrect prefix matching from `CSIVolumeByID` breaks prefix
matching in the command line client. Add the required elements for prefix
matching to the commands and API.
This change fixes a bug where lost/failed allocations are replaced by
allocations with the latest versions, even if the version hasn't been
promoted yet.
Now, when generating a plan for lost/failed allocations, the scheduler
first checks if the current deployment is in Canary stage, and if so, it
ensures that any lost/failed allocations is replaced one with the latest
promoted version instead.
* nomad/structs/csi: split CanWrite into health, in use
* scheduler/scheduler: expose AllocByID in the state interface
* nomad/state/state_store_test
* scheduler/stack: SetJobID on the matcher
* scheduler/feasible: when a volume writer is in use, check if it's us
* scheduler/feasible: remove SetJob
* nomad/state/state_store: denormalize allocs before Claim
* nomad/structs/csi: return errors on claim, with context
* nomad/csi_endpoint_test: new alloc doesn't look like an update
* nomad/state/state_store_test: change test reference to CanWrite
* 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
