open-nomad/nomad/leader_test.go

package nomad

import (
	"errors"
	"fmt"
	"sort"
	"strconv"
	"testing"
	"time"

	"github.com/hashicorp/consul/sdk/testutil/retry"
	"github.com/hashicorp/go-hclog"
	memdb "github.com/hashicorp/go-memdb"
	"github.com/hashicorp/go-version"
	"github.com/hashicorp/nomad/ci"
	"github.com/hashicorp/nomad/helper"
	"github.com/hashicorp/nomad/nomad/mock"
	"github.com/hashicorp/nomad/nomad/state"
	"github.com/hashicorp/nomad/nomad/structs"
	"github.com/hashicorp/nomad/testutil"
	"github.com/hashicorp/raft"
	"github.com/hashicorp/serf/serf"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestLeader_LeftServer(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS3()
	servers := []*Server{s1, s2, s3}
	TestJoin(t, s1, s2, s3)

	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			peers, _ := s.numPeers()
			return peers == 3, nil
		}, func(err error) {
			t.Fatalf("should have 3 peers")
		})
	}

	// Kill any server
	var peer *Server
	for _, s := range servers {
		if !s.IsLeader() {
			peer = s
			break
		}
	}
	if peer == nil {
		t.Fatalf("Should have a non-leader")
	}
	peer.Shutdown()
	name := fmt.Sprintf("%s.%s", peer.config.NodeName, peer.config.Region)

	testutil.WaitForResult(func() (bool, error) {
		for _, s := range servers {
			if s == peer {
				continue
			}

			// Force remove the non-leader (transition to left state)
			if err := s.RemoveFailedNode(name); err != nil {
				return false, err
			}

			peers, _ := s.numPeers()
			return peers == 2, errors.New(fmt.Sprintf("%v", peers))
		}

		return true, nil
	}, func(err error) {
		t.Fatalf("err: %s", err)
	})
}

func TestLeader_LeftLeader(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS3()
	servers := []*Server{s1, s2, s3}
	TestJoin(t, s1, s2, s3)

	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			peers, _ := s.numPeers()
			return peers == 3, nil
		}, func(err error) {
			t.Fatalf("should have 3 peers")
		})
	}

	// Kill the leader!
	leader := waitForStableLeadership(t, servers)

	leader.Leave()
	leader.Shutdown()

	for _, s := range servers {
		if s == leader {
			continue
		}
		testutil.WaitForResult(func() (bool, error) {
			peers, _ := s.numPeers()
			return peers == 2, errors.New(fmt.Sprintf("%v", peers))
		}, func(err error) {
			t.Fatalf("should have 2 peers: %v", err)
		})
	}
}

func TestLeader_MultiBootstrap(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, nil)
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, nil)
	defer cleanupS2()
	servers := []*Server{s1, s2}
	TestJoin(t, s1, s2)

	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			peers := s.Members()
			return len(peers) == 2, nil
		}, func(err error) {
			t.Fatalf("should have 2 peers")
		})
	}

	// Ensure we don't have multiple raft peers
	for _, s := range servers {
		peers, err := s.numPeers()
		if err != nil {
			t.Fatalf("failed: %v", err)
		}
		if peers != 1 {
			t.Fatalf("should only have 1 raft peer! %v", peers)
		}
	}
}

func TestLeader_PlanQueue_Reset(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
	})
	defer cleanupS3()
	servers := []*Server{s1, s2, s3}
	TestJoin(t, s1, s2, s3)

	leader := waitForStableLeadership(t, servers)

	if !leader.planQueue.Enabled() {
		t.Fatalf("should enable plan queue")
	}

	for _, s := range servers {
		if !s.IsLeader() && s.planQueue.Enabled() {
			t.Fatalf("plan queue should not be enabled")
		}
	}

	// Kill the leader
	leader.Shutdown()
	time.Sleep(100 * time.Millisecond)

	// Wait for a new leader
	leader = nil
	testutil.WaitForResult(func() (bool, error) {
		for _, s := range servers {
			if s.IsLeader() {
				leader = s
				return true, nil
			}
		}
		return false, nil
	}, func(err error) {
		t.Fatalf("should have leader")
	})

	// Check that the new leader has a pending GC expiration
	testutil.WaitForResult(func() (bool, error) {
		return leader.planQueue.Enabled(), nil
	}, func(err error) {
		t.Fatalf("should enable plan queue")
	})
}

func TestLeader_EvalBroker_Reset(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.BootstrapExpect = 3
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.BootstrapExpect = 3
	})
	defer cleanupS3()
	servers := []*Server{s1, s2, s3}
	TestJoin(t, s1, s2, s3)

	leader := waitForStableLeadership(t, servers)

	// Inject a pending eval
	req := structs.EvalUpdateRequest{
		Evals: []*structs.Evaluation{mock.Eval()},
	}
	_, _, err := leader.raftApply(structs.EvalUpdateRequestType, req)
	if err != nil {
		t.Fatalf("err: %v", err)
	}

	// Kill the leader
	leader.Shutdown()
	time.Sleep(100 * time.Millisecond)

	// Wait for a new leader
	leader = nil
	testutil.WaitForResult(func() (bool, error) {
		for _, s := range servers {
			if s.IsLeader() {
				leader = s
				return true, nil
			}
		}
		return false, nil
	}, func(err error) {
		t.Fatalf("should have leader")
	})

	// Check that the new leader has a pending evaluation
	testutil.WaitForResult(func() (bool, error) {
		stats := leader.evalBroker.Stats()
		return stats.TotalReady == 1, nil
	}, func(err error) {
		t.Fatalf("should have pending evaluation")
	})
}

func TestLeader_PeriodicDispatcher_Restore_Adds(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.BootstrapExpect = 3
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.BootstrapExpect = 3
	})
	defer cleanupS3()
	servers := []*Server{s1, s2, s3}
	TestJoin(t, s1, s2, s3)

	leader := waitForStableLeadership(t, servers)

	// Inject a periodic job, a parameterized periodic job and a non-periodic job
	periodic := mock.PeriodicJob()
	nonPeriodic := mock.Job()
	parameterizedPeriodic := mock.PeriodicJob()
	parameterizedPeriodic.ParameterizedJob = &structs.ParameterizedJobConfig{}
	for _, job := range []*structs.Job{nonPeriodic, periodic, parameterizedPeriodic} {
		req := structs.JobRegisterRequest{
			Job: job,
			WriteRequest: structs.WriteRequest{
				Namespace: job.Namespace,
			},
		}
		_, _, err := leader.raftApply(structs.JobRegisterRequestType, req)
		if err != nil {
			t.Fatalf("err: %v", err)
		}
	}

	// Kill the leader
	leader.Shutdown()
	time.Sleep(100 * time.Millisecond)

	// Wait for a new leader
	leader = nil
	testutil.WaitForResult(func() (bool, error) {
		for _, s := range servers {
			if s.IsLeader() {
				leader = s
				return true, nil
			}
		}
		return false, nil
	}, func(err error) {
		t.Fatalf("should have leader")
	})

	tuplePeriodic := structs.NamespacedID{
		ID:        periodic.ID,
		Namespace: periodic.Namespace,
	}
	tupleNonPeriodic := structs.NamespacedID{
		ID:        nonPeriodic.ID,
		Namespace: nonPeriodic.Namespace,
	}
	tupleParameterized := structs.NamespacedID{
		ID:        parameterizedPeriodic.ID,
		Namespace: parameterizedPeriodic.Namespace,
	}

	// Check that the new leader is tracking the periodic job only
	testutil.WaitForResult(func() (bool, error) {
		leader.periodicDispatcher.l.Lock()
		defer leader.periodicDispatcher.l.Unlock()
		if _, tracked := leader.periodicDispatcher.tracked[tuplePeriodic]; !tracked {
			return false, fmt.Errorf("periodic job not tracked")
		}
		if _, tracked := leader.periodicDispatcher.tracked[tupleNonPeriodic]; tracked {
			return false, fmt.Errorf("non periodic job tracked")
		}
		if _, tracked := leader.periodicDispatcher.tracked[tupleParameterized]; tracked {
			return false, fmt.Errorf("parameterized periodic job tracked")
		}
		return true, nil
	}, func(err error) {
		t.Fatalf(err.Error())
	})
}

func TestLeader_PeriodicDispatcher_Restore_NoEvals(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	// Inject a periodic job that will be triggered soon.
	launch := time.Now().Add(1 * time.Second)
	job := testPeriodicJob(launch)
	req := structs.JobRegisterRequest{
		Job: job,
		WriteRequest: structs.WriteRequest{
			Namespace: job.Namespace,
		},
	}
	_, _, err := s1.raftApply(structs.JobRegisterRequestType, req)
	if err != nil {
		t.Fatalf("err: %v", err)
	}

	// Flush the periodic dispatcher, ensuring that no evals will be created.
	s1.periodicDispatcher.SetEnabled(false)

	// Get the current time to ensure the launch time is after this once we
	// restore.
	now := time.Now()

	// Sleep till after the job should have been launched.
	time.Sleep(3 * time.Second)

	// Restore the periodic dispatcher.
	s1.periodicDispatcher.SetEnabled(true)
	s1.restorePeriodicDispatcher()

	// Ensure the job is tracked.
	tuple := structs.NamespacedID{
		ID:        job.ID,
		Namespace: job.Namespace,
	}
	if _, tracked := s1.periodicDispatcher.tracked[tuple]; !tracked {
		t.Fatalf("periodic job not restored")
	}

	// Check that an eval was made.
	ws := memdb.NewWatchSet()
	last, err := s1.fsm.State().PeriodicLaunchByID(ws, job.Namespace, job.ID)
	if err != nil || last == nil {
		t.Fatalf("failed to get periodic launch time: %v", err)
	}

	if last.Launch.Before(now) {
		t.Fatalf("restorePeriodicDispatcher did not force launch: last %v; want after %v", last.Launch, now)
	}
}

func TestLeader_PeriodicDispatcher_Restore_Evals(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	// Inject a periodic job that triggered once in the past, should trigger now
	// and once in the future.
	now := time.Now()
	past := now.Add(-1 * time.Second)
	future := now.Add(10 * time.Second)
	job := testPeriodicJob(past, now, future)
	req := structs.JobRegisterRequest{
		Job: job,
		WriteRequest: structs.WriteRequest{
			Namespace: job.Namespace,
		},
	}
	_, _, err := s1.raftApply(structs.JobRegisterRequestType, req)
	if err != nil {
		t.Fatalf("err: %v", err)
	}

	// Create an eval for the past launch.
	s1.periodicDispatcher.createEval(job, past)

	// Flush the periodic dispatcher, ensuring that no evals will be created.
	s1.periodicDispatcher.SetEnabled(false)

	// Sleep till after the job should have been launched.
	time.Sleep(3 * time.Second)

	// Restore the periodic dispatcher.
	s1.periodicDispatcher.SetEnabled(true)
	s1.restorePeriodicDispatcher()

	// Ensure the job is tracked.
	tuple := structs.NamespacedID{
		ID:        job.ID,
		Namespace: job.Namespace,
	}
	if _, tracked := s1.periodicDispatcher.tracked[tuple]; !tracked {
		t.Fatalf("periodic job not restored")
	}

	// Check that an eval was made.
	ws := memdb.NewWatchSet()
	last, err := s1.fsm.State().PeriodicLaunchByID(ws, job.Namespace, job.ID)
	if err != nil || last == nil {
		t.Fatalf("failed to get periodic launch time: %v", err)
	}
	if last.Launch == past {
		t.Fatalf("restorePeriodicDispatcher did not force launch")
	}
}

func TestLeader_PeriodicDispatch(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.EvalGCInterval = 5 * time.Millisecond
	})
	defer cleanupS1()

	// Wait for a periodic dispatch
	testutil.WaitForResult(func() (bool, error) {
		stats := s1.evalBroker.Stats()
		bySched, ok := stats.ByScheduler[structs.JobTypeCore]
		if !ok {
			return false, nil
		}
		return bySched.Ready > 0, nil
	}, func(err error) {
		t.Fatalf("should pending job")
	})
}

func TestLeader_ReapFailedEval(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.EvalDeliveryLimit = 1
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	// Wait for a periodic dispatch
	eval := mock.Eval()
	s1.evalBroker.Enqueue(eval)

	// Dequeue and Nack
	out, token, err := s1.evalBroker.Dequeue(defaultSched, time.Second)
	if err != nil {
		t.Fatalf("err: %v", err)
	}
	s1.evalBroker.Nack(out.ID, token)

	// Wait for an updated and followup evaluation
	state := s1.fsm.State()
	testutil.WaitForResult(func() (bool, error) {
		ws := memdb.NewWatchSet()
		out, err := state.EvalByID(ws, eval.ID)
		if err != nil {
			return false, err
		}
		if out == nil {
			return false, fmt.Errorf("expect original evaluation to exist")
		}
		if out.Status != structs.EvalStatusFailed {
			return false, fmt.Errorf("got status %v; want %v", out.Status, structs.EvalStatusFailed)
		}
		if out.NextEval == "" {
			return false, fmt.Errorf("got empty NextEval")
		}
		// See if there is a followup
		evals, err := state.EvalsByJob(ws, eval.Namespace, eval.JobID)
		if err != nil {
			return false, err
		}

		if l := len(evals); l != 2 {
			return false, fmt.Errorf("got %d evals, want 2", l)
		}

		for _, e := range evals {
			if e.ID == eval.ID {
				continue
			}

			if e.Status != structs.EvalStatusPending {
				return false, fmt.Errorf("follow up eval has status %v; want %v",
					e.Status, structs.EvalStatusPending)
			}

			if e.ID != out.NextEval {
				return false, fmt.Errorf("follow up eval id is %v; orig eval NextEval %v",
					e.ID, out.NextEval)
			}

			if e.Wait < s1.config.EvalFailedFollowupBaselineDelay ||
				e.Wait > s1.config.EvalFailedFollowupBaselineDelay+s1.config.EvalFailedFollowupDelayRange {
				return false, fmt.Errorf("bad wait: %v", e.Wait)
			}

			if e.TriggeredBy != structs.EvalTriggerFailedFollowUp {
				return false, fmt.Errorf("follow up eval TriggeredBy %v; want %v",
					e.TriggeredBy, structs.EvalTriggerFailedFollowUp)
			}
		}

		return true, nil
	}, func(err error) {
		t.Fatalf("err: %v", err)
	})
}

func TestLeader_ReapDuplicateEval(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	// Create a duplicate blocked eval
	eval := mock.Eval()
	eval.CreateIndex = 100
	eval2 := mock.Eval()
	eval2.JobID = eval.JobID
	eval2.CreateIndex = 102
	s1.blockedEvals.Block(eval)
	s1.blockedEvals.Block(eval2)

	// Wait for the evaluation to marked as cancelled
	state := s1.fsm.State()
	testutil.WaitForResult(func() (bool, error) {
		ws := memdb.NewWatchSet()
		out, err := state.EvalByID(ws, eval.ID)
		if err != nil {
			return false, err
		}
		return out != nil && out.Status == structs.EvalStatusCancelled, nil
	}, func(err error) {
		t.Fatalf("err: %v", err)
	})
}

func TestLeader_revokeVaultAccessorsOnRestore(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	// Insert a vault accessor that should be revoked
	fsmState := s1.fsm.State()
	va := mock.VaultAccessor()
	if err := fsmState.UpsertVaultAccessor(100, []*structs.VaultAccessor{va}); err != nil {
		t.Fatalf("bad: %v", err)
	}

	// Swap the Vault client
	tvc := &TestVaultClient{}
	s1.vault = tvc

	// Do a restore
	if err := s1.revokeVaultAccessorsOnRestore(); err != nil {
		t.Fatalf("Failed to restore: %v", err)
	}

	if len(tvc.RevokedTokens) != 1 && tvc.RevokedTokens[0].Accessor != va.Accessor {
		t.Fatalf("Bad revoked accessors: %v", tvc.RevokedTokens)
	}
}

func TestLeader_revokeSITokenAccessorsOnRestore(t *testing.T) {
	ci.Parallel(t)
	r := require.New(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	// replace consul ACLs API with a mock for tracking calls in tests
	var consulACLsAPI mockConsulACLsAPI
	s1.consulACLs = &consulACLsAPI

	// Insert a SI token accessor that should be revoked
	fsmState := s1.fsm.State()
	accessor := mock.SITokenAccessor()
	err := fsmState.UpsertSITokenAccessors(100, []*structs.SITokenAccessor{accessor})
	r.NoError(err)

	// Do a restore
	err = s1.revokeSITokenAccessorsOnRestore()
	r.NoError(err)

	// Check the accessor was revoked
	exp := []revokeRequest{{
		accessorID: accessor.AccessorID,
		committed:  true,
	}}
	r.ElementsMatch(exp, consulACLsAPI.revokeRequests)
}

func TestLeader_ClusterID(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 0
		c.Build = minClusterIDVersion.String()
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	clusterID, err := s1.ClusterID()

	require.NoError(t, err)
	require.True(t, helper.IsUUID(clusterID))
}

func TestLeader_ClusterID_upgradePath(t *testing.T) {
	ci.Parallel(t)

	before := version.Must(version.NewVersion("0.10.1")).String()
	after := minClusterIDVersion.String()

	type server struct {
		s       *Server
		cleanup func()
	}

	outdated := func() server {
		s, cleanup := TestServer(t, func(c *Config) {
			c.NumSchedulers = 0
			c.Build = before
			c.BootstrapExpect = 3
			c.Logger.SetLevel(hclog.Trace)
		})
		return server{s: s, cleanup: cleanup}
	}

	upgraded := func() server {
		s, cleanup := TestServer(t, func(c *Config) {
			c.NumSchedulers = 0
			c.Build = after
			c.BootstrapExpect = 0
			c.Logger.SetLevel(hclog.Trace)
		})
		return server{s: s, cleanup: cleanup}
	}

	servers := []server{outdated(), outdated(), outdated()}
	// fallback shutdown attempt in case testing fails
	defer servers[0].cleanup()
	defer servers[1].cleanup()
	defer servers[2].cleanup()

	upgrade := func(i int) {
		previous := servers[i]

		servers[i] = upgraded()
		TestJoin(t, servers[i].s, servers[(i+1)%3].s, servers[(i+2)%3].s)
		testutil.WaitForLeader(t, servers[i].s.RPC)

		require.NoError(t, previous.s.Leave())
		require.NoError(t, previous.s.Shutdown())
	}

	// Join the servers before doing anything
	TestJoin(t, servers[0].s, servers[1].s, servers[2].s)

	// Wait for servers to settle
	for i := 0; i < len(servers); i++ {
		testutil.WaitForLeader(t, servers[i].s.RPC)
	}

	// A check that ClusterID is not available yet
	noIDYet := func() {
		for _, s := range servers {
			retry.Run(t, func(r *retry.R) {
				if _, err := s.s.ClusterID(); err == nil {
					r.Error("expected error")
				}
			})
		}
	}

	// Replace first old server with new server
	upgrade(0)
	defer servers[0].cleanup()
	noIDYet() // ClusterID should not work yet, servers: [new, old, old]

	// Replace second old server with new server
	upgrade(1)
	defer servers[1].cleanup()
	noIDYet() // ClusterID should not work yet, servers: [new, new, old]

	// Replace third / final old server with new server
	upgrade(2)
	defer servers[2].cleanup()

	// Wait for old servers to really be gone
	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			peers, _ := s.s.numPeers()
			return peers == 3, nil
		}, func(_ error) {
			t.Fatalf("should have 3 peers")
		})
	}

	// Now we can tickle the leader into making a cluster ID
	leaderID := ""
	for _, s := range servers {
		if s.s.IsLeader() {
			id, err := s.s.ClusterID()
			require.NoError(t, err)
			leaderID = id
			break
		}
	}
	require.True(t, helper.IsUUID(leaderID))

	// Now every participating server has been upgraded, each one should be
	// able to get the cluster ID, having been plumbed all the way through.
	agreeClusterID(t, []*Server{servers[0].s, servers[1].s, servers[2].s})
}

func TestLeader_ClusterID_noUpgrade(t *testing.T) {
	ci.Parallel(t)

	type server struct {
		s       *Server
		cleanup func()
	}

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.Logger.SetLevel(hclog.Trace)
		c.NumSchedulers = 0
		c.Build = minClusterIDVersion.String()
		c.BootstrapExpect = 3
	})
	defer cleanupS1()
	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.Logger.SetLevel(hclog.Trace)
		c.NumSchedulers = 0
		c.Build = minClusterIDVersion.String()
		c.BootstrapExpect = 3
	})
	defer cleanupS2()
	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.Logger.SetLevel(hclog.Trace)
		c.NumSchedulers = 0
		c.Build = minClusterIDVersion.String()
		c.BootstrapExpect = 3
	})
	defer cleanupS3()

	servers := []*Server{s1, s2, s3}

	// Join the servers before doing anything
	TestJoin(t, servers[0], servers[1], servers[2])

	// Wait for servers to settle
	for i := 0; i < len(servers); i++ {
		testutil.WaitForLeader(t, servers[i].RPC)
	}

	// Each server started at the minimum version, check there should be only 1
	// cluster ID they all agree on.
	agreeClusterID(t, []*Server{servers[0], servers[1], servers[2]})
}

func agreeClusterID(t *testing.T, servers []*Server) {
	retries := &retry.Timer{Timeout: 60 * time.Second, Wait: 1 * time.Second}
	ids := make([]string, 3)
	for i, s := range servers {
		retry.RunWith(retries, t, func(r *retry.R) {
			id, err := s.ClusterID()
			if err != nil {
				r.Error(err.Error())
				return
			}
			if !helper.IsUUID(id) {
				r.Error("not a UUID")
				return
			}
			ids[i] = id
		})
	}
	require.True(t, ids[0] == ids[1] && ids[1] == ids[2], "ids[0] %s, ids[1] %s, ids[2] %s", ids[0], ids[1], ids[2])
}

func TestLeader_ReplicateACLPolicies(t *testing.T) {
	ci.Parallel(t)

	s1, root, cleanupS1 := TestACLServer(t, func(c *Config) {
		c.Region = "region1"
		c.AuthoritativeRegion = "region1"
		c.ACLEnabled = true
	})
	defer cleanupS1()
	s2, _, cleanupS2 := TestACLServer(t, func(c *Config) {
		c.Region = "region2"
		c.AuthoritativeRegion = "region1"
		c.ACLEnabled = true
		c.ReplicationBackoff = 20 * time.Millisecond
		c.ReplicationToken = root.SecretID
	})
	defer cleanupS2()
	TestJoin(t, s1, s2)
	testutil.WaitForLeader(t, s1.RPC)
	testutil.WaitForLeader(t, s2.RPC)

	// Write a policy to the authoritative region
	p1 := mock.ACLPolicy()
	if err := s1.State().UpsertACLPolicies(structs.MsgTypeTestSetup, 100, []*structs.ACLPolicy{p1}); err != nil {
		t.Fatalf("bad: %v", err)
	}

	// Wait for the policy to replicate
	testutil.WaitForResult(func() (bool, error) {
		state := s2.State()
		out, err := state.ACLPolicyByName(nil, p1.Name)
		return out != nil, err
	}, func(err error) {
		t.Fatalf("should replicate policy")
	})
}

func TestLeader_DiffACLPolicies(t *testing.T) {
	ci.Parallel(t)

	state := state.TestStateStore(t)

	// Populate the local state
	p1 := mock.ACLPolicy()
	p2 := mock.ACLPolicy()
	p3 := mock.ACLPolicy()
	assert.Nil(t, state.UpsertACLPolicies(structs.MsgTypeTestSetup, 100, []*structs.ACLPolicy{p1, p2, p3}))

	// Simulate a remote list
	p2Stub := p2.Stub()
	p2Stub.ModifyIndex = 50 // Ignored, same index
	p3Stub := p3.Stub()
	p3Stub.ModifyIndex = 100 // Updated, higher index
	p3Stub.Hash = []byte{0, 1, 2, 3}
	p4 := mock.ACLPolicy()
	remoteList := []*structs.ACLPolicyListStub{
		p2Stub,
		p3Stub,
		p4.Stub(),
	}
	delete, update := diffACLPolicies(state, 50, remoteList)

	// P1 does not exist on the remote side, should delete
	assert.Equal(t, []string{p1.Name}, delete)

	// P2 is un-modified - ignore. P3 modified, P4 new.
	assert.Equal(t, []string{p3.Name, p4.Name}, update)
}

func TestLeader_ReplicateACLTokens(t *testing.T) {
	ci.Parallel(t)

	s1, root, cleanupS1 := TestACLServer(t, func(c *Config) {
		c.Region = "region1"
		c.AuthoritativeRegion = "region1"
		c.ACLEnabled = true
	})
	defer cleanupS1()
	s2, _, cleanupS2 := TestACLServer(t, func(c *Config) {
		c.Region = "region2"
		c.AuthoritativeRegion = "region1"
		c.ACLEnabled = true
		c.ReplicationBackoff = 20 * time.Millisecond
		c.ReplicationToken = root.SecretID
	})
	defer cleanupS2()
	TestJoin(t, s1, s2)
	testutil.WaitForLeader(t, s1.RPC)
	testutil.WaitForLeader(t, s2.RPC)

	// Write a token to the authoritative region
	p1 := mock.ACLToken()
	p1.Global = true
	if err := s1.State().UpsertACLTokens(structs.MsgTypeTestSetup, 100, []*structs.ACLToken{p1}); err != nil {
		t.Fatalf("bad: %v", err)
	}

	// Wait for the token to replicate
	testutil.WaitForResult(func() (bool, error) {
		state := s2.State()
		out, err := state.ACLTokenByAccessorID(nil, p1.AccessorID)
		return out != nil, err
	}, func(err error) {
		t.Fatalf("should replicate token")
	})
}

func TestLeader_DiffACLTokens(t *testing.T) {
	ci.Parallel(t)

	state := state.TestStateStore(t)

	// Populate the local state
	p0 := mock.ACLToken()
	p1 := mock.ACLToken()
	p1.Global = true
	p2 := mock.ACLToken()
	p2.Global = true
	p3 := mock.ACLToken()
	p3.Global = true
	assert.Nil(t, state.UpsertACLTokens(structs.MsgTypeTestSetup, 100, []*structs.ACLToken{p0, p1, p2, p3}))

	// Simulate a remote list
	p2Stub := p2.Stub()
	p2Stub.ModifyIndex = 50 // Ignored, same index
	p3Stub := p3.Stub()
	p3Stub.ModifyIndex = 100 // Updated, higher index
	p3Stub.Hash = []byte{0, 1, 2, 3}
	p4 := mock.ACLToken()
	p4.Global = true
	remoteList := []*structs.ACLTokenListStub{
		p2Stub,
		p3Stub,
		p4.Stub(),
	}
	delete, update := diffACLTokens(state, 50, remoteList)

	// P0 is local and should be ignored
	// P1 does not exist on the remote side, should delete
	assert.Equal(t, []string{p1.AccessorID}, delete)

	// P2 is un-modified - ignore. P3 modified, P4 new.
	assert.Equal(t, []string{p3.AccessorID, p4.AccessorID}, update)
}

func TestLeader_UpgradeRaftVersion(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.Datacenter = "dc1"
		c.RaftConfig.ProtocolVersion = 2
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 1
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 2
	})
	defer cleanupS3()

	servers := []*Server{s1, s2, s3}

	// Try to join
	TestJoin(t, s1, s2, s3)

	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			peers, _ := s.numPeers()
			return peers == 3, nil
		}, func(err error) {
			t.Fatalf("should have 3 peers")
		})
	}

	// Kill the v1 server
	if err := s2.Leave(); err != nil {
		t.Fatal(err)
	}

	for _, s := range []*Server{s1, s3} {
		minVer, err := s.autopilot.MinRaftProtocol()
		if err != nil {
			t.Fatal(err)
		}
		if got, want := minVer, 2; got != want {
			t.Fatalf("got min raft version %d want %d", got, want)
		}
	}

	// Replace the dead server with one running raft protocol v3
	s4, cleanupS4 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.Datacenter = "dc1"
		c.RaftConfig.ProtocolVersion = 3
	})
	defer cleanupS4()
	TestJoin(t, s1, s4)
	servers[1] = s4

	// Make sure we're back to 3 total peers with the new one added via ID
	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			addrs := 0
			ids := 0
			future := s.raft.GetConfiguration()
			if err := future.Error(); err != nil {
				return false, err
			}
			for _, server := range future.Configuration().Servers {
				if string(server.ID) == string(server.Address) {
					addrs++
				} else {
					ids++
				}
			}
			if got, want := addrs, 2; got != want {
				return false, fmt.Errorf("got %d server addresses want %d", got, want)
			}
			if got, want := ids, 1; got != want {
				return false, fmt.Errorf("got %d server ids want %d", got, want)
			}

			return true, nil
		}, func(err error) {
			t.Fatal(err)
		})
	}
}

func TestLeader_Reelection(t *testing.T) {
	ci.Parallel(t)

	raftProtocols := []int{1, 2, 3}
	for _, p := range raftProtocols {
		t.Run(fmt.Sprintf("Leader Election - Protocol version %d", p), func(t *testing.T) {
			leaderElectionTest(t, raft.ProtocolVersion(p))
		})
	}

}

func leaderElectionTest(t *testing.T, raftProtocol raft.ProtocolVersion) {
	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = raftProtocol
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = raftProtocol
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = raftProtocol
	})
	defer cleanupS3() // todo(shoenig) added this, should be here right??

	servers := []*Server{s1, s2, s3}

	// Try to join
	TestJoin(t, s1, s2, s3)
	testutil.WaitForLeader(t, s1.RPC)

	testutil.WaitForResult(func() (bool, error) {
		future := s1.raft.GetConfiguration()
		if err := future.Error(); err != nil {
			return false, err
		}

		for _, server := range future.Configuration().Servers {
			if server.Suffrage == raft.Nonvoter {
				return false, fmt.Errorf("non-voter %v", server)
			}
		}

		return true, nil
	}, func(err error) {
		t.Fatal(err)
	})

	var leader, nonLeader *Server
	for _, s := range servers {
		if s.IsLeader() {
			leader = s
		} else {
			nonLeader = s
		}
	}

	// Shutdown the leader
	leader.Shutdown()
	// Wait for new leader to elect
	testutil.WaitForLeader(t, nonLeader.RPC)
}

func TestLeader_RollRaftServer(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.RaftConfig.ProtocolVersion = 2
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 2
	})
	defer cleanupS2()

	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 2
	})
	defer cleanupS3()

	servers := []*Server{s1, s2, s3}

	// Try to join
	TestJoin(t, s1, s2, s3)

	for _, s := range servers {
		retry.Run(t, func(r *retry.R) { r.Check(wantPeers(s, 3)) })
	}

	// Kill the first v2 server
	s1.Shutdown()

	for _, s := range []*Server{s2, s3} {
		s.RemoveFailedNode(s1.config.NodeID)

		retry.Run(t, func(r *retry.R) {
			minVer, err := s.autopilot.MinRaftProtocol()
			if err != nil {
				r.Fatal(err)
			}
			if got, want := minVer, 2; got != want {
				r.Fatalf("got min raft version %d want %d", got, want)
			}

			configFuture := s.raft.GetConfiguration()
			if err != nil {
				r.Fatal(err)
			}
			if len(configFuture.Configuration().Servers) != 2 {
				r.Fatalf("expected 2 servers, got %d", len(configFuture.Configuration().Servers))
			}
		})
	}

	// Replace the dead server with one running raft protocol v3
	s4, cleanupS4 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 3
	})
	defer cleanupS4()
	TestJoin(t, s2, s3, s4)
	servers[0] = s4

	// Kill the second v2 server
	s2.Shutdown()

	for _, s := range []*Server{s3, s4} {
		s.RemoveFailedNode(s2.config.NodeID)

		retry.RunWith(&retry.Counter{
			Count: int(10 * testutil.TestMultiplier()),
			Wait:  time.Duration(testutil.TestMultiplier()) * time.Second,
		}, t, func(r *retry.R) {
			minVer, err := s.autopilot.MinRaftProtocol()
			if err != nil {
				r.Fatal(err)
			}
			if got, want := minVer, 2; got != want {
				r.Fatalf("got min raft version %d want %d", got, want)
			}

			configFuture := s.raft.GetConfiguration()
			if err != nil {
				r.Fatal(err)
			}
			if len(configFuture.Configuration().Servers) != 2 {
				r.Fatalf("expected 2 servers, got %d", len(configFuture.Configuration().Servers))
			}
		})
	}
	// Replace another dead server with one running raft protocol v3
	s5, cleanupS5 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 3
	})
	defer cleanupS5()
	TestJoin(t, s3, s4, s5)
	servers[1] = s5

	// Kill the last v2 server, now minRaftProtocol should be 3
	s3.Shutdown()

	for _, s := range []*Server{s4, s5} {
		s.RemoveFailedNode(s2.config.NodeID)

		retry.RunWith(&retry.Counter{
			Count: int(10 * testutil.TestMultiplier()),
			Wait:  time.Duration(testutil.TestMultiplier()) * time.Second,
		}, t, func(r *retry.R) {
			minVer, err := s.autopilot.MinRaftProtocol()
			if err != nil {
				r.Fatal(err)
			}
			if got, want := minVer, 3; got != want {
				r.Fatalf("got min raft version %d want %d", got, want)
			}

			configFuture := s.raft.GetConfiguration()
			if err != nil {
				r.Fatal(err)
			}
			if len(configFuture.Configuration().Servers) != 2 {
				r.Fatalf("expected 2 servers, got %d", len(configFuture.Configuration().Servers))
			}
		})
	}

	// Replace the last dead server with one running raft protocol v3
	s6, cleanupS6 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 3
		c.RaftConfig.ProtocolVersion = 3
	})
	defer cleanupS6()
	TestJoin(t, s6, s4)
	servers[2] = s6

	// Make sure all the dead servers are removed and we're back to 3 total peers
	for _, s := range servers {
		retry.Run(t, func(r *retry.R) {
			addrs := 0
			ids := 0
			future := s.raft.GetConfiguration()
			if err := future.Error(); err != nil {
				r.Fatal(err)
			}
			for _, server := range future.Configuration().Servers {
				if string(server.ID) == string(server.Address) {
					addrs++
				} else {
					ids++
				}
			}
			if got, want := addrs, 0; got != want {
				r.Fatalf("got %d server addresses want %d", got, want)
			}
			if got, want := ids, 3; got != want {
				r.Fatalf("got %d server ids want %d", got, want)
			}
		})
	}
}

func TestLeader_RevokeLeadership_MultipleTimes(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, nil)
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	testutil.WaitForResult(func() (bool, error) {
		return s1.evalBroker.Enabled(), nil
	}, func(err error) {
		t.Fatalf("should have finished establish leader loop")
	})

	require.Nil(t, s1.revokeLeadership())
	require.Nil(t, s1.revokeLeadership())
	require.Nil(t, s1.revokeLeadership())
}

func TestLeader_TransitionsUpdateConsistencyRead(t *testing.T) {
	ci.Parallel(t)

	s1, cleanupS1 := TestServer(t, nil)
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)

	testutil.WaitForResult(func() (bool, error) {
		return s1.isReadyForConsistentReads(), nil
	}, func(err error) {
		require.Fail(t, "should have finished establish leader loop")
	})

	require.Nil(t, s1.revokeLeadership())
	require.False(t, s1.isReadyForConsistentReads())

	ch := make(chan struct{})
	require.Nil(t, s1.establishLeadership(ch))
	require.True(t, s1.isReadyForConsistentReads())
}

// TestLeader_PausingWorkers asserts that scheduling workers are paused
// (and unpaused) upon leader elections (and step downs).
func TestLeader_PausingWorkers(t *testing.T) {
	ci.Parallel(t)
	
	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.NumSchedulers = 12
	})
	defer cleanupS1()
	testutil.WaitForLeader(t, s1.RPC)
	require.Len(t, s1.workers, 12)

	// this satisfies the require.Eventually test interface
	checkPaused := func(count int) func() bool {
		return func() bool {
			pausedWorkers := func() int {
				c := 0
				for _, w := range s1.workers {
					if w.IsPaused() {
						c++
					}
				}
				return c
			}

			return pausedWorkers() == count
		}
	}

	// acquiring leadership should have paused 3/4 of the workers
	require.Eventually(t, checkPaused(9), 1*time.Second, 10*time.Millisecond, "scheduler workers did not pause within a second at leadership change")

	err := s1.revokeLeadership()
	require.NoError(t, err)

	// unpausing is a relatively quick activity
	require.Eventually(t, checkPaused(0), 50*time.Millisecond, 10*time.Millisecond, "scheduler workers should have unpaused after losing leadership")
}

// Test doing an inplace upgrade on a server from raft protocol 2 to 3
// This verifies that removing the server and adding it back with a uuid works
// even if the server's address stays the same.
func TestServer_ReconcileMember(t *testing.T) {
	ci.Parallel(t)

	// Create a three node cluster
	s1, cleanupS1 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 2
		c.RaftConfig.ProtocolVersion = 3
	})
	defer cleanupS1()

	s2, cleanupS2 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 2
		c.RaftConfig.ProtocolVersion = 3
	})
	defer cleanupS2()

	TestJoin(t, s1, s2)
	testutil.WaitForLeader(t, s1.RPC)

	// test relies on s3 not being the leader, so adding it
	// after leadership has been established to reduce
	s3, cleanupS3 := TestServer(t, func(c *Config) {
		c.BootstrapExpect = 0
		c.RaftConfig.ProtocolVersion = 2
	})
	defer cleanupS3()

	TestJoin(t, s1, s3)

	// Create a memberlist object for s3, with raft protocol upgraded to 3
	upgradedS3Member := serf.Member{
		Name:   s3.config.NodeName,
		Addr:   s3.config.RPCAddr.IP,
		Status: serf.StatusAlive,
		Tags:   make(map[string]string),
	}
	upgradedS3Member.Tags["role"] = "nomad"
	upgradedS3Member.Tags["id"] = s3.config.NodeID
	upgradedS3Member.Tags["region"] = s3.config.Region
	upgradedS3Member.Tags["dc"] = s3.config.Datacenter
	upgradedS3Member.Tags["rpc_addr"] = "127.0.0.1"
	upgradedS3Member.Tags["port"] = strconv.Itoa(s3.config.RPCAddr.Port)
	upgradedS3Member.Tags["build"] = "0.8.0"
	upgradedS3Member.Tags["vsn"] = "2"
	upgradedS3Member.Tags["mvn"] = "1"
	upgradedS3Member.Tags["raft_vsn"] = "3"

	findLeader := func(t *testing.T) *Server {
		t.Helper()
		for _, s := range []*Server{s1, s2, s3} {
			if s.IsLeader() {
				t.Logf("found leader: %v %v", s.config.NodeID, s.config.RPCAddr)
				return s
			}
		}

		t.Fatalf("no leader found")
		return nil
	}

	// Find the leader so that we can call reconcile member on it
	leader := findLeader(t)
	if err := leader.reconcileMember(upgradedS3Member); err != nil {
		t.Fatalf("failed to reconcile member: %v", err)
	}

	// This should remove s3 from the config and potentially cause a leader election
	testutil.WaitForLeader(t, s1.RPC)

	// Figure out the new leader and call reconcile again, this should add s3 with the new ID format
	leader = findLeader(t)
	if err := leader.reconcileMember(upgradedS3Member); err != nil {
		t.Fatalf("failed to reconcile member: %v", err)
	}

	testutil.WaitForLeader(t, s1.RPC)
	future := s2.raft.GetConfiguration()
	if err := future.Error(); err != nil {
		t.Fatal(err)
	}
	addrs := 0
	ids := 0
	for _, server := range future.Configuration().Servers {
		if string(server.ID) == string(server.Address) {
			addrs++
		} else {
			ids++
		}
	}
	// After this, all three servers should have IDs in raft
	if got, want := addrs, 0; got != want {
		t.Fatalf("got %d server addresses want %d", got, want)
	}
	if got, want := ids, 3; got != want {
		t.Fatalf("got %d server ids want %d: %#v", got, want, future.Configuration().Servers)
	}
}

func TestLeader_ReplicateNamespaces(t *testing.T) {
	ci.Parallel(t)
	assert := assert.New(t)
	s1, root, cleanupS1 := TestACLServer(t, func(c *Config) {
		c.Region = "region1"
		c.AuthoritativeRegion = "region1"
		c.ACLEnabled = true
	})
	defer cleanupS1()
	s2, _, cleanupS2 := TestACLServer(t, func(c *Config) {
		c.Region = "region2"
		c.AuthoritativeRegion = "region1"
		c.ACLEnabled = true
		c.ReplicationBackoff = 20 * time.Millisecond
		c.ReplicationToken = root.SecretID
	})
	defer cleanupS2()
	TestJoin(t, s1, s2)
	testutil.WaitForLeader(t, s1.RPC)
	testutil.WaitForLeader(t, s2.RPC)

	// Write a namespace to the authoritative region
	ns1 := mock.Namespace()
	assert.Nil(s1.State().UpsertNamespaces(100, []*structs.Namespace{ns1}))

	// Wait for the namespace to replicate
	testutil.WaitForResult(func() (bool, error) {
		state := s2.State()
		out, err := state.NamespaceByName(nil, ns1.Name)
		return out != nil, err
	}, func(err error) {
		t.Fatalf("should replicate namespace")
	})

	// Delete the namespace at the authoritative region
	assert.Nil(s1.State().DeleteNamespaces(200, []string{ns1.Name}))

	// Wait for the namespace deletion to replicate
	testutil.WaitForResult(func() (bool, error) {
		state := s2.State()
		out, err := state.NamespaceByName(nil, ns1.Name)
		return out == nil, err
	}, func(err error) {
		t.Fatalf("should replicate namespace deletion")
	})
}

func TestLeader_DiffNamespaces(t *testing.T) {
	ci.Parallel(t)

	state := state.TestStateStore(t)

	// Populate the local state
	ns1 := mock.Namespace()
	ns2 := mock.Namespace()
	ns3 := mock.Namespace()
	assert.Nil(t, state.UpsertNamespaces(100, []*structs.Namespace{ns1, ns2, ns3}))

	// Simulate a remote list
	rns2 := ns2.Copy()
	rns2.ModifyIndex = 50 // Ignored, same index
	rns3 := ns3.Copy()
	rns3.ModifyIndex = 100 // Updated, higher index
	rns3.Hash = []byte{0, 1, 2, 3}
	ns4 := mock.Namespace()
	remoteList := []*structs.Namespace{
		rns2,
		rns3,
		ns4,
	}
	delete, update := diffNamespaces(state, 50, remoteList)
	sort.Strings(delete)

	// ns1 does not exist on the remote side, should delete
	assert.Equal(t, []string{structs.DefaultNamespace, ns1.Name}, delete)

	// ns2 is un-modified - ignore. ns3 modified, ns4 new.
	assert.Equal(t, []string{ns3.Name, ns4.Name}, update)
}

// waitForStableLeadership waits until a leader is elected and all servers
// get promoted as voting members, returns the leader
func waitForStableLeadership(t *testing.T, servers []*Server) *Server {
	nPeers := len(servers)

	// wait for all servers to discover each other
	for _, s := range servers {
		testutil.WaitForResult(func() (bool, error) {
			peers, _ := s.numPeers()
			if peers != nPeers {
				return false, fmt.Errorf("should find %d peers but found %d", nPeers, peers)
			}

			return true, nil
		}, func(err error) {
			require.NoError(t, err)
		})
	}

	// wait for leader
	var leader *Server
	testutil.WaitForResult(func() (bool, error) {
		for _, s := range servers {
			if s.IsLeader() {
				leader = s
				return true, nil
			}
		}

		return false, fmt.Errorf("no leader found")
	}, func(err error) {
		require.NoError(t, err)
	})

	// wait for all servers get marked as voters
	testutil.WaitForResult(func() (bool, error) {
		future := leader.raft.GetConfiguration()
		if err := future.Error(); err != nil {
			return false, fmt.Errorf("failed to get raft config: %v", future.Error())
		}
		ss := future.Configuration().Servers
		if len(ss) != len(servers) {
			return false, fmt.Errorf("raft doesn't contain all servers.  Expected %d but found %d", len(servers), len(ss))
		}

		for _, s := range ss {
			if s.Suffrage != raft.Voter {
				return false, fmt.Errorf("configuration has non voting server: %v", s)
			}
		}

		return true, nil
	}, func(err error) {
		require.NoError(t, err)
	})

	return leader
}