Change the interface of ServiceDiscovery

Instead of passing state, signal that the state has changed and provide a callback handler that can query Core.

command/server.go

@@ -290,7 +290,21 @@ func (c *ServerCommand) Run(args []string) int {
 	if coreConfig.HAPhysical != nil {
 		sd, ok := coreConfig.HAPhysical.(physical.ServiceDiscovery)
 		if ok {
-			if err := sd.RunServiceDiscovery(c.ShutdownCh, coreConfig.AdvertiseAddr); err != nil {
+			activeFunc := func() bool {
+				if isLeader, _, err := core.Leader(); err != nil {
+					return isLeader
+				}
+				return false
+			}
+
+			sealedFunc := func() bool {
+				if sealed, err := core.Sealed(); err != nil {
+					return sealed
+				}
+				return true
+			}
+
+			if err := sd.RunServiceDiscovery(c.ShutdownCh, coreConfig.AdvertiseAddr, activeFunc, sealedFunc); err != nil {
 				c.Ui.Error(fmt.Sprintf("Error initializing service discovery: %v", err))
 				return 1
 			}

physical/physical.go

@@ -48,21 +48,27 @@ type AdvertiseDetect interface {
 	DetectHostAddr() (string, error)
 }
 
+// Callback signatures for RunServiceDiscovery
+type activeFunction func() bool
+type sealedFunction func() bool
+
 // ServiceDiscovery is an optional interface that an HABackend can implement.
 // If they do, the state of a backend is advertised to the service discovery
 // network.
 type ServiceDiscovery interface {
-	// AdvertiseActive is used to reflect whether or not a backend is in
-	// an active or standby state.
-	AdvertiseActive(bool) error
+	// NotifyActiveStateChange is used by Core to notify a backend
+	// capable of ServiceDiscovery that this Vault instance has changed
+	// its status to active or standby.
+	NotifyActiveStateChange() error
 
-	// AdvertiseSealed is used to reflect whether or not a backend is in
-	// a sealed state or not.
-	AdvertiseSealed(bool) error
+	// NotifySealedStateChange is used by Core to notify a backend
+	// capable of ServiceDiscovery that Vault has changed its Sealed
+	// status to sealed or unsealed.
+	NotifySealedStateChange() error
 
 	// Run executes any background service discovery tasks until the
 	// shutdown channel is closed.
-	RunServiceDiscovery(shutdownCh ShutdownChannel, advertiseAddr string) error
+	RunServiceDiscovery(shutdownCh ShutdownChannel, advertiseAddr string, activeFunc activeFunction, sealedFunc sealedFunction) error
 }
 
 type Lock interface {

vault/core.go

@@ -945,11 +945,9 @@ func (c *Core) Unseal(key []byte) (bool, error) {
 	if c.ha != nil {
 		sd, ok := c.ha.(physical.ServiceDiscovery)
 		if ok {
-			go func() {
-				if err := sd.AdvertiseSealed(false); err != nil {
-					c.logger.Printf("[WARN] core: failed to advertise unsealed status: %v", err)
-				}
-			}()
+			if err := sd.NotifySealedStateChange(); err != nil {
+				c.logger.Printf("[WARN] core: failed to notify unsealed status: %v", err)
+			}
 		}
 	}
 	return true, nil
@@ -1100,11 +1098,9 @@ func (c *Core) sealInternal() error {
 	if c.ha != nil {
 		sd, ok := c.ha.(physical.ServiceDiscovery)
 		if ok {
-			go func() {
-				if err := sd.AdvertiseSealed(true); err != nil {
-					c.logger.Printf("[WARN] core: failed to advertise sealed status: %v", err)
-				}
-			}()
+			if err := sd.NotifySealedStateChange(); err != nil {
+				c.logger.Printf("[WARN] core: failed to notify sealed status: %v", err)
+			}
 		}
 	}
 
@@ -1424,11 +1420,9 @@ func (c *Core) advertiseLeader(uuid string, leaderLostCh <-chan struct{}) error
 
 	sd, ok := c.ha.(physical.ServiceDiscovery)
 	if ok {
-		go func() {
-			if err := sd.AdvertiseActive(true); err != nil {
-				c.logger.Printf("[WARN] core: failed to advertise active status: %v", err)
-			}
-		}()
+		if err := sd.NotifyActiveStateChange(); err != nil {
+			c.logger.Printf("[WARN] core: failed to notify active status: %v", err)
+		}
 	}
 	return nil
 }
@@ -1460,11 +1454,9 @@ func (c *Core) clearLeader(uuid string) error {
 	// Advertise ourselves as a standby
 	sd, ok := c.ha.(physical.ServiceDiscovery)
 	if ok {
-		go func() {
-			if err := sd.AdvertiseActive(false); err != nil {
-				c.logger.Printf("[WARN] core: failed to advertise standby status: %v", err)
-			}
-		}()
+		if err := sd.NotifyActiveStateChange(); err != nil {
+			c.logger.Printf("[WARN] core: failed to notify standby status: %v", err)
+		}
 	}
 
 	return err