Don't swallow errors in the docker client.

common/docker/client.go

@@ -7,7 +7,7 @@ import (
 
 // An observer for container events
 type ContainerObserver interface {
-	ContainerDied(ident string) error
+	ContainerDied(ident string)
 }
 
 type Client struct {

ipam/allocator.go

@@ -223,12 +223,10 @@ func (alloc *Allocator) Claim(ident string, addr address.Address) error {
 }
 
 // ContainerDied is provided to satisfy the updater interface; does a 'Delete' underneath.  Sync.
-func (alloc *Allocator) ContainerDied(ident string) error {
-	err := alloc.Delete(ident)
-	if err == nil {
+func (alloc *Allocator) ContainerDied(ident string) {
+	if err := alloc.Delete(ident); err == nil {
 		alloc.debugln("Container", ident, "died; released addresses")
 	}
-	return err
 }
 
 // Delete (Sync) - release all IP addresses for container with given name

nameserver/nameserver.go

@@ -120,7 +120,7 @@ func (n *Nameserver) ReverseLookup(ip address.Address) (string, error) {
 	return match.Hostname, nil
 }
 
-func (n *Nameserver) ContainerDied(ident string) error {
+func (n *Nameserver) ContainerDied(ident string) {
 	n.Lock()
 	entries := n.entries.tombstone(n.ourName, func(e *Entry) bool {
 		if e.ContainerID == ident {
@@ -130,10 +130,12 @@ func (n *Nameserver) ContainerDied(ident string) error {
 		return false
 	})
 	n.Unlock()
-	if n.gossip != nil {
-		return n.gossip.GossipBroadcast(entries)
+	if n.gossip != nil && len(*entries) > 0 {
+		err := n.gossip.GossipBroadcast(entries)
+		if err != nil {
+			n.errorf("Failed to broadcast container '%s' death: %v", ident, err)
+		}
 	}
-	return nil
 }
 
 func (n *Nameserver) PeerGone(peer *router.Peer) {
@@ -253,3 +255,6 @@ func (n *Nameserver) infof(fmt string, args ...interface{}) {
 func (n *Nameserver) debugf(fmt string, args ...interface{}) {
 	Log.Debugf("[nameserver %s] "+fmt, append([]interface{}{n.ourName}, args...)...)
 }
+func (n *Nameserver) errorf(fmt string, args ...interface{}) {
+	Log.Errorf("[nameserver %s] "+fmt, append([]interface{}{n.ourName}, args...)...)
+}

nameserver/nameserver_test.go

@@ -205,8 +205,7 @@ func TestContainerAndPeerDeath(t *testing.T) {
 	require.Nil(t, err)
 	require.Equal(t, []address.Address{0}, nameserver.Lookup("hostname"))
 
-	err = nameserver.ContainerDied("containerid")
-	require.Nil(t, err)
+	nameserver.ContainerDied("containerid")
 	require.Equal(t, []address.Address{}, nameserver.Lookup("hostname"))
 
 	err = nameserver.AddEntry("hostname", "containerid", peername, address.Address(0))