Here, we ensure that when leader only responds to RPC calls when state
store is up to date. At leadership transition or launch with restored
state, the server local store might not be caught up with latest raft
logs and may return a stale read.
The solution here is to have an RPC consistency read gate, enabled when
`establishLeadership` completes before we respond to RPC calls.
`establishLeadership` is gated by a `raft.Barrier` which ensures that
all prior raft logs have been applied.
Conversely, the gate is disabled when leadership is lost.
This is very much inspired by https://github.com/hashicorp/consul/pull/3154/files
Race was test only and due to unlocked map access.
Panic was test only and due to checking a field on a struct even when we
knew the struct was nil.
Race output that was fixed:
```
==================
WARNING: DATA RACE
Read at 0x00c000697dd0 by goroutine 768:
runtime.mapaccess2()
/usr/local/go/src/runtime/map.go:439 +0x0
github.com/hashicorp/nomad/nomad.TestLeader_PeriodicDispatcher_Restore_Adds.func8()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader_test.go:402
+0xe6
github.com/hashicorp/nomad/testutil.WaitForResultRetries()
/home/schmichael/go/src/github.com/hashicorp/nomad/testutil/wait.go:30
+0x5a
github.com/hashicorp/nomad/testutil.WaitForResult()
/home/schmichael/go/src/github.com/hashicorp/nomad/testutil/wait.go:22
+0x57
github.com/hashicorp/nomad/nomad.TestLeader_PeriodicDispatcher_Restore_Adds()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader_test.go:401
+0xb53
testing.tRunner()
/usr/local/go/src/testing/testing.go:827 +0x162
Previous write at 0x00c000697dd0 by goroutine 569:
runtime.mapassign()
/usr/local/go/src/runtime/map.go:549 +0x0
github.com/hashicorp/nomad/nomad.(*PeriodicDispatch).Add()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/periodic.go:224
+0x2eb
github.com/hashicorp/nomad/nomad.(*Server).restorePeriodicDispatcher()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader.go:394
+0x29a
github.com/hashicorp/nomad/nomad.(*Server).establishLeadership()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader.go:234
+0x593
github.com/hashicorp/nomad/nomad.(*Server).leaderLoop()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader.go:117
+0x82e
github.com/hashicorp/nomad/nomad.(*Server).monitorLeadership.func1()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader.go:72
+0x6c
Goroutine 768 (running) created at:
testing.(*T).Run()
/usr/local/go/src/testing/testing.go:878 +0x650
testing.runTests.func1()
/usr/local/go/src/testing/testing.go:1119 +0xa8
testing.tRunner()
/usr/local/go/src/testing/testing.go:827 +0x162
testing.runTests()
/usr/local/go/src/testing/testing.go:1117 +0x4ee
testing.(*M).Run()
/usr/local/go/src/testing/testing.go:1034 +0x2ee
main.main()
_testmain.go:1150 +0x221
Goroutine 569 (running) created at:
github.com/hashicorp/nomad/nomad.(*Server).monitorLeadership()
/home/schmichael/go/src/github.com/hashicorp/nomad/nomad/leader.go:70
+0x269
==================
```
Token revocation
Remove from the statestore
Revoke tokens
Don't error when Vault is disabled as this could cause issue if the operator ever goes from enabled to disabled
update server interface to allow enable/disable and config loading
test the new functions
Leader revoke
Use active
Mahmood Ali