client/heartbeatstop: don't store client state, use timeout

In order to minimize this change while keeping a simple version of the
behavior, we set `lastOk` to the current time less the intial server
connection timeout. If the client starts and never contacts the
server, it will stop all configured tasks after the initial server
connection grace period, on the assumption that we've been out of
touch longer than any configured `stop_after_client_disconnect`.

The more complex state behavior might be justified later, but we
should learn about failure modes first.

client/client.go

@@ -371,9 +371,6 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulServic
 			}, // TODO(tgross): refactor these dispenser constructors into csimanager to tidy it up
 		})
 
-	// create heartbeatStop, and restore its previous state from the state store. Post init for the stateDB
-	c.heartbeatStop = newHeartbeatStop(c.stateDB, c.getAllocRunner, logger, c.shutdownCh)
-
 	// Setup the clients RPC server
 	c.setupClientRpc()
 
@@ -448,9 +445,13 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulServic
 	c.pluginManagers.RegisterAndRun(devManager)
 
 	// Batching of initial fingerprints is done to reduce the number of node
-	// updates sent to the server on startup.
+	// updates sent to the server on startup. This is the first RPC to the servers
 	go c.batchFirstFingerprints()
 
+	// create heartbeatStop. We go after the first attempt to connect to the server, so
+	// that our grace period for connection goes for the full time
+	c.heartbeatStop = newHeartbeatStop(c.getAllocRunner, batchFirstFingerprintsTimeout, logger, c.shutdownCh)
+
 	// Watch for disconnection, and heartbeatStopAllocs configured to have a maximum
 	// lifetime when out of touch with the server
 	go c.heartbeatStop.watch()
@@ -1764,7 +1765,7 @@ func (c *Client) registerNode() error {
 
 	c.heartbeatLock.Lock()
 	defer c.heartbeatLock.Unlock()
-	c.heartbeatStop.setLastOk()
+	c.heartbeatStop.setLastOk(time.Now())
 	c.heartbeatTTL = resp.HeartbeatTTL
 	return nil
 }
@@ -1793,7 +1794,7 @@ func (c *Client) updateNodeStatus() error {
 	last := c.lastHeartbeat()
 	oldTTL := c.heartbeatTTL
 	haveHeartbeated := c.haveHeartbeated
-	c.heartbeatStop.setLastOk()
+	c.heartbeatStop.setLastOk(time.Now())
 	c.heartbeatTTL = resp.HeartbeatTTL
 	c.haveHeartbeated = true
 	c.heartbeatLock.Unlock()

client/heartbeatstop.go

@@ -5,44 +5,36 @@ import (
 	"time"
 
 	hclog "github.com/hashicorp/go-hclog"
-	"github.com/hashicorp/nomad/client/state"
 	"github.com/hashicorp/nomad/nomad/structs"
 )
 
 type heartbeatStop struct {
 	lastOk        time.Time
+	startupGrace  time.Time
 	allocInterval map[string]time.Duration
 	allocHookCh   chan *structs.Allocation
 	getRunner     func(string) (AllocRunner, error)
 	logger        hclog.InterceptLogger
-	state         state.StateDB
 	shutdownCh    chan struct{}
 	lock          *sync.RWMutex
 }
 
 func newHeartbeatStop(
-	state state.StateDB,
 	getRunner func(string) (AllocRunner, error),
+	timeout time.Duration,
 	logger hclog.InterceptLogger,
 	shutdownCh chan struct{}) *heartbeatStop {
 
 	h := &heartbeatStop{
+		startupGrace:  time.Now().Add(timeout),
 		allocInterval: make(map[string]time.Duration),
 		allocHookCh:   make(chan *structs.Allocation),
 		getRunner:     getRunner,
 		logger:        logger,
-		state:         state,
 		shutdownCh:    shutdownCh,
 		lock:          &sync.RWMutex{},
 	}
 
-	if state != nil {
-		lastOk, err := state.GetLastHeartbeatOk()
-		if err == nil && !lastOk.IsZero() {
-			h.lastOk = lastOk
-		}
-	}
-
 	return h
 }
 
@@ -60,12 +52,18 @@ func (h *heartbeatStop) allocHook(alloc *structs.Allocation) {
 func (h *heartbeatStop) shouldStop(alloc *structs.Allocation) bool {
 	tg := allocTaskGroup(alloc)
 	if tg.StopAfterClientDisconnect != nil {
-		now := time.Now()
-		return now.After(h.lastOk.Add(*tg.StopAfterClientDisconnect))
+		return h.shouldStopAfter(time.Now(), *tg.StopAfterClientDisconnect)
 	}
 	return false
 }
 
+func (h *heartbeatStop) shouldStopAfter(now time.Time, interval time.Duration) bool {
+	if h.lastOk.IsZero() {
+		return h.startupGrace.After(now)
+	}
+	return now.After(h.lastOk.Add(interval))
+}
+
 // watch is a loop that checks for allocations that should be stopped. It also manages the
 // registration of allocs to be stopped in a single thread.
 func (h *heartbeatStop) watch() {
@@ -116,24 +114,18 @@ func (h *heartbeatStop) watch() {
 
 		now = time.Now()
 		for allocID, d := range h.allocInterval {
-			if now.After(h.lastOk.Add(d)) {
+			if h.shouldStopAfter(now, d) {
 				stop <- allocID
 			}
 		}
 	}
 }
 
 // setLastOk sets the last known good heartbeat time to the current time, and persists that time to disk
-func (h *heartbeatStop) setLastOk() error {
+func (h *heartbeatStop) setLastOk(t time.Time) {
 	h.lock.Lock()
 	defer h.lock.Unlock()
-	t := time.Now()
 	h.lastOk = t
-	// We may encounter an error here, but want to update the running time
-	// unconditionally, since we'll actively terminate stateful tasks if it ages too
-	// much. We only use the state value when restarting the client itself after a
-	// crash, so it's better to update the runtime value and have the stored value stale
-	return h.state.PutLastHeartbeatOk(t)
 }
 
 func (h *heartbeatStop) getLastOk() time.Time {

client/heartbeatstop_test.go

@@ -23,13 +23,6 @@ func TestHearbeatStop_allocHook(t *testing.T) {
 	})
 	defer cleanupC1()
 
-	// last heartbeat is persisted in the state db
-	err := client.registerNode()
-	require.NoError(t, err)
-	last, err := client.stateDB.GetLastHeartbeatOk()
-	require.NoError(t, err)
-	require.Empty(t, last)
-
 	// an allocation, with a tiny lease
 	d := 1 * time.Microsecond
 	alloc := &structs.Allocation{
@@ -51,7 +44,7 @@ func TestHearbeatStop_allocHook(t *testing.T) {
 	}
 
 	// alloc added to heartbeatStop.allocs
-	err = client.addAlloc(alloc, "")
+	err := client.addAlloc(alloc, "")
 	require.NoError(t, err)
 	testutil.WaitForResult(func() (bool, error) {
 		_, ok := client.heartbeatStop.allocInterval[alloc.ID]

client/state/interface.go

@@ -1,8 +1,6 @@
 package state
 
 import (
-	"time"
-
 	"github.com/hashicorp/nomad/client/allocrunner/taskrunner/state"
 	dmstate "github.com/hashicorp/nomad/client/devicemanager/state"
 	"github.com/hashicorp/nomad/client/dynamicplugins"
@@ -78,13 +76,6 @@ type StateDB interface {
 	// PutDynamicPluginRegistryState is used to store the dynamic plugin managers's state.
 	PutDynamicPluginRegistryState(state *dynamicplugins.RegistryState) error
 
-	// GetLastHeartbeatOk retrieves the stored last known good heartbeat
-	GetLastHeartbeatOk() (time.Time, error)
-
-	// PutLastHeartbeatOk stores the last heartbeat known to have made the round trip to
-	// the server
-	PutLastHeartbeatOk(time.Time) error
-
 	// Close the database. Unsafe for further use after calling regardless
 	// of return value.
 	Close() error

client/state/memdb.go

@@ -2,7 +2,6 @@ package state
 
 import (
 	"sync"
-	"time"
 
 	hclog "github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/nomad/client/allocrunner/taskrunner/state"
@@ -34,9 +33,6 @@ type MemDB struct {
 	// dynamicmanager -> registry-state
 	dynamicManagerPs *dynamicplugins.RegistryState
 
-	// lastHeartbeatOk -> last_heartbeat_ok
-	lastHeartbeatOk time.Time
-
 	logger hclog.Logger
 
 	mu sync.RWMutex
@@ -93,19 +89,6 @@ func (m *MemDB) PutDeploymentStatus(allocID string, ds *structs.AllocDeploymentS
 	return nil
 }
 
-func (m *MemDB) GetLastHeartbeatOk() (time.Time, error) {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-	return m.lastHeartbeatOk, nil
-}
-
-func (m *MemDB) PutLastHeartbeatOk(t time.Time) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
-	m.lastHeartbeatOk = t
-	return nil
-}
-
 func (m *MemDB) GetTaskRunnerState(allocID string, taskName string) (*state.LocalState, *structs.TaskState, error) {
 	m.mu.RLock()
 	defer m.mu.RUnlock()

client/state/noopdb.go

@@ -1,8 +1,6 @@
 package state
 
 import (
-	"time"
-
 	"github.com/hashicorp/nomad/client/allocrunner/taskrunner/state"
 	dmstate "github.com/hashicorp/nomad/client/devicemanager/state"
 	"github.com/hashicorp/nomad/client/dynamicplugins"
@@ -81,14 +79,6 @@ func (n NoopDB) GetDynamicPluginRegistryState() (*dynamicplugins.RegistryState,
 	return nil, nil
 }
 
-func (n NoopDB) PutLastHeartbeatOk(t time.Time) error {
-	return nil
-}
-
-func (n NoopDB) GetLastHeartbeatOk() (time.Time, error) {
-	return time.Time{}, nil
-}
-
 func (n NoopDB) Close() error {
 	return nil
 }

client/state/state_database.go

@@ -91,12 +91,6 @@ var (
 
 	// registryStateKey is the key at which dynamic plugin registry state is stored
 	registryStateKey = []byte("registry_state")
-
-	// lastHeartbeatOkBucket is the bucket for storing the last known good heartbeat time
-	lastHeartbeatOkBucket = []byte("last_heartbeat_ok")
-
-	// lastHeartbeatOkKey is the key for the last known good heartbeat time
-	lastHeartbeatOkKey = []byte("last_heartbeat")
 )
 
 // taskBucketName returns the bucket name for the given task name.
@@ -661,51 +655,6 @@ func (s *BoltStateDB) GetDynamicPluginRegistryState() (*dynamicplugins.RegistryS
 	return ps, nil
 }
 
-// PutLastHeartbeatOk stores the dynamic plugin registry's
-// state or returns an error.
-func (s *BoltStateDB) PutLastHeartbeatOk(t time.Time) error {
-	return s.db.Update(func(tx *boltdd.Tx) error {
-		// Retrieve the root dynamic plugin manager bucket
-		dynamicBkt, err := tx.CreateBucketIfNotExists(lastHeartbeatOkBucket)
-		if err != nil {
-			return err
-		}
-
-		return dynamicBkt.Put(lastHeartbeatOkKey, t.Unix())
-	})
-}
-
-// GetLastHeartbeatOk stores the dynamic plugin registry's
-// registry state or returns an error.
-func (s *BoltStateDB) GetLastHeartbeatOk() (time.Time, error) {
-	var unix int64
-	err := s.db.View(func(tx *boltdd.Tx) error {
-		dynamicBkt := tx.Bucket(lastHeartbeatOkBucket)
-		if dynamicBkt == nil {
-			// No state, return
-			return nil
-		}
-
-		// Restore Plugin State if it exists
-		if err := dynamicBkt.Get(lastHeartbeatOkKey, unix); err != nil {
-			if !boltdd.IsErrNotFound(err) {
-				return fmt.Errorf("failed to read last heartbeat state: %v", err)
-			}
-
-			// Key not found, reset output to nil
-			unix = 0
-		}
-
-		return nil
-	})
-
-	if err != nil {
-		return time.Time{}, err
-	}
-
-	return time.Unix(unix, 0), nil
-}
-
 // init initializes metadata entries in a newly created state database.
 func (s *BoltStateDB) init() error {
 	return s.db.Update(func(tx *boltdd.Tx) error {