Pulls in latest Serf to get flap metric.

Godeps/Godeps.json

@@ -1,6 +1,7 @@
 {
 	"ImportPath": "github.com/hashicorp/consul",
 	"GoVersion": "go1.6",
+	"GodepVersion": "v74",
 	"Deps": [
 		{
 			"ImportPath": "github.com/DataDog/datadog-go/statsd",
@@ -225,13 +226,13 @@
 		},
 		{
 			"ImportPath": "github.com/hashicorp/serf/coordinate",
-			"Comment": "v0.7.0-12-ge4ec8cc",
-			"Rev": "e4ec8cc423bbe20d26584b96efbeb9102e16d05f"
+			"Comment": "v0.7.0-62-gb60a6d9",
+			"Rev": "b60a6d928fe726a588f79a1d500582507f9d79de"
 		},
 		{
 			"ImportPath": "github.com/hashicorp/serf/serf",
-			"Comment": "v0.7.0-12-ge4ec8cc",
-			"Rev": "e4ec8cc423bbe20d26584b96efbeb9102e16d05f"
+			"Comment": "v0.7.0-62-gb60a6d9",
+			"Rev": "b60a6d928fe726a588f79a1d500582507f9d79de"
 		},
 		{
 			"ImportPath": "github.com/hashicorp/yamux",

vendor/github.com/hashicorp/serf/coordinate/README.md

@@ -1 +0,0 @@
-# TODO - I'll beef this up as I implement each of the enhancements.

vendor/github.com/hashicorp/serf/coordinate/config.go

@@ -16,7 +16,7 @@ package coordinate
 type Config struct {
 	// The dimensionality of the coordinate system. As discussed in [2], more
 	// dimensions improves the accuracy of the estimates up to a point. Per [2]
-	// we chose 4 dimensions plus a non-Euclidean height.
+	// we chose 8 dimensions plus a non-Euclidean height.
 	Dimensionality uint
 
 	// VivaldiErrorMax is the default error value when a node hasn't yet made

vendor/github.com/hashicorp/serf/serf/config.go

@@ -103,6 +103,13 @@ type Config struct {
 	ReconnectTimeout  time.Duration
 	TombstoneTimeout  time.Duration
 
+	// FlapTimeout is the amount of time less than which we consider a node
+	// being failed and rejoining looks like a flap for telemetry purposes.
+	// This should be set less than a typical reboot time, but large enough
+	// to see actual events, given our expected detection times for a failed
+	// node.
+	FlapTimeout time.Duration
+
 	// QueueDepthWarning is used to generate warning message if the
 	// number of queued messages to broadcast exceeds this number. This
 	// is to provide the user feedback if events are being triggered
@@ -241,6 +248,7 @@ func DefaultConfig() *Config {
 		QueueDepthWarning:            128,
 		MaxQueueDepth:                4096,
 		TombstoneTimeout:             24 * time.Hour,
+		FlapTimeout:                  60 * time.Second,
 		MemberlistConfig:             memberlist.DefaultLANConfig(),
 		QueryTimeoutMult:             16,
 		QueryResponseSizeLimit:       1024,

vendor/github.com/hashicorp/serf/serf/serf.go

@@ -871,6 +871,11 @@ func (s *Serf) handleNodeJoin(n *memberlist.Node) {
 		s.members[n.Name] = member
 	} else {
 		oldStatus = member.Status
+		deadTime := time.Now().Sub(member.leaveTime)
+		if oldStatus == StatusFailed && deadTime < s.config.FlapTimeout {
+			metrics.IncrCounter([]string{"serf", "member", "flap"}, 1)
+		}
+
 		member.Status = StatusAlive
 		member.leaveTime = time.Time{}
 		member.Addr = net.IP(n.Addr)