Integration points for multiregion jobs to be registered in the enterprise
version of Nomad:
* hook in `Job.Register` for enterprise to send job to peer regions
* remove monitoring from `nomad job run` and `nomad job stop` for multiregion jobs
* scheduler/reconcile: set FollowupEvalID on lost stop_after_client_disconnect
* scheduler/reconcile: thread follupEvalIDs through to results.stop
* scheduler/reconcile: comment typo
* nomad/_test: correct arguments for plan.AppendStoppedAlloc
* scheduler/reconcile: avoid nil, cleanup handleDelayed(Lost|Reschedules)
* client/heartbeatstop: reversed time condition for startup grace
* scheduler/generic_sched: use `delayInstead` to avoid a loop
Without protecting the loop that creates followUpEvals, a delayed eval
is allowed to create an immediate subsequent delayed eval. For both
`stop_after_client_disconnect` and the `reschedule` block, a delayed
eval should always produce some immediate result (running or blocked)
and then only after the outcome of that eval produce a second delayed
eval.
* scheduler/reconcile: lostLater are different than delayedReschedules
Just slightly. `lostLater` allocs should be used to create batched
evaluations, but `handleDelayedReschedules` assumes that the
allocations are in the untainted set. When it creates the in-place
updates to those allocations at the end, it causes the allocation to
be treated as running over in the planner, which causes the initial
`stop_after_client_disconnect` evaluation to be retried by the worker.
Handle case where a snapshot is made before cluster metadata is created.
This fixes a bug where a server may have empty cluster metadata if it
created and installed a Raft snapshot before a new cluster metadata ID is
generated.
This case is very unlikely to arise. Most likely reason is when
upgrading from an old version slowly where servers may use snapshots
before all servers upgrade. This happened for a user with a log line
like:
```
2020-05-21T15:21:56.996Z [ERROR] nomad.fsm: ClusterSetMetadata failed: error=""set cluster metadata failed: refusing to set new cluster id, previous: , new: <<redacted>
```
* changes necessary to support oss licesning shims
revert nomad fmt changes
update test to work with enterprise changes
update tests to work with new ent enforcements
make check
update cas test to use scheduler algorithm
back out preemption changes
add comments
* remove unused method
Ensure that nomad steps down (and terminate leader goroutines) on
shutdown, when the server is the leader.
Without this change, `monitorLeadership` may handle `shutdownCh` event
and exit early before handling the raft `leaderCh` event and end up
leaking leadership goroutines.
If a token is scheduled for revocation expires before we revoke it,
ensure that it is marked as purged in raft and is only removed from
local vault state if the purge operation succeeds.
Prior to this change, we may remove the accessor from local state but
not purge it from Raft. This causes unnecessary and churn in the next
leadership elections (and until 0.11.2 result in indefinite retries).
