Fix a case where `node.StatusUpdatedAt` was manipulated directly in
memory.
This ensures that StatusUpdatedAt is set in raft layer, and ensures that
the field is updated when node drain/eligibility is updated too.
Fixes https://github.com/hashicorp/nomad/issues/4299
Upon investigating this case further, we determined the issue to be a race between applying `JobBatchDeregisterRequest` fsm operation and processing job-deregister evals.
Processing job-deregister evals should wait until the FSM log message finishes applying, by using the snapshot index. However, with `JobBatchDeregister`, any single individual job deregistering was applied accidentally incremented the snapshot index and resulted into processing job-deregister evals. When a Nomad server receives an eval for a job in the batch that is yet to be deleted, we accidentally re-run it depending on the state of allocation.
This change ensures that we delete deregister all of the jobs and inserts all evals in a single transactions, thus blocking processing related evals until deregistering complete.
This commit implements an allocation selection algorithm for finding
allocations to preempt. It currently special cases network resource asks
from others (cpu/memory/disk/iops).
This PR cancels deployments that are active but do not have a job
associated with them. This is a broken invariant that causes issues in
the deployment watcher since it will not track them. Thus they are
objects that can't be operated on or cleaned up.
Fixes https://github.com/hashicorp/nomad/issues/4286
This PR allows marking a node as eligible for scheduling while toggling
drain. By default the `nomad node drain -disable` commmand will mark it
as eligible but the drainer will maintain in-eligibility.
