diff --git a/cluster/swarm/cluster.go b/cluster/swarm/cluster.go
index ab6f49a3f3..b2934029d5 100644
--- a/cluster/swarm/cluster.go
+++ b/cluster/swarm/cluster.go
@@ -141,10 +141,10 @@ func (c *Cluster) newEntries(entries []*discovery.Entry) {
 
 				if old, exists := c.engines[engine.ID]; exists {
 					c.Unlock()
-					if old.IP != engine.IP {
-						log.Errorf("ID duplicated. %s shared by %s and %s", engine.ID, old.IP, engine.IP)
+					if old.Addr != engine.Addr {
+						log.Errorf("ID duplicated. %s shared by %s and %s", engine.ID, old.Addr, engine.Addr)
 					} else {
-						log.Errorf("node %q with IP %q is  already registered", engine.Name, engine.IP)
+						log.Debugf("node %q (name: %q) with address %q is already registered", engine.ID, engine.Name, engine.Addr)
 					}
 					return
 				}
diff --git a/test/integration/discovery-file.bats b/test/integration/discovery-file.bats
new file mode 100644
index 0000000000..98b91557c9
--- /dev/null
+++ b/test/integration/discovery-file.bats
@@ -0,0 +1,34 @@
+#!/usr/bin/env bats
+
+load helpers
+
+# create a blank temp file for discovery
+DISCOVERY_FILE=$(mktemp)
+
+function teardown() {
+	swarm_manage_cleanup
+	stop_docker
+	rm -f "$DISCOVERY_FILE"
+}
+
+function setup_file_discovery() {
+	rm -f "$DISCOVERY_FILE"
+	for host in ${HOSTS[@]}; do
+		echo "$host" >> $DISCOVERY_FILE
+	done
+}
+
+@test "file discovery" {
+	# Start 2 engines, register them in a file, then start swarm and make sure
+	# it sees them.
+	start_docker 2
+	setup_file_discovery
+	swarm_manage "file://$DISCOVERY_FILE"
+	check_swarm_nodes
+
+	# Add another engine to the cluster, update the discovery file and make
+	# sure it's picked up by swarm.
+	start_docker 1
+	setup_file_discovery
+	retry 10 1 check_swarm_nodes
+}
diff --git a/test/integration/discovery-token.bats b/test/integration/discovery-token.bats
new file mode 100644
index 0000000000..877954fbf9
--- /dev/null
+++ b/test/integration/discovery-token.bats
@@ -0,0 +1,39 @@
+#!/usr/bin/env bats
+
+load helpers
+
+TOKEN=""
+
+function token_cleanup() {
+	[ -z "$TOKEN" ] && return
+	echo "Removing $TOKEN"
+	curl -X DELETE "https://discovery-stage.hub.docker.com/v1/clusters/$TOKEN"
+}
+
+function teardown() {
+	swarm_manage_cleanup
+	swarm_join_cleanup
+	stop_docker
+	token_cleanup
+}
+
+@test "token discovery" {
+	# Create a cluster and validate the token.
+	run swarm create
+	[ "$status" -eq 0 ]
+	[[ "$output" =~ ^[0-9a-f]{32}$ ]]
+	TOKEN="$output"
+
+	# Start 2 engines and make them join the cluster.
+	start_docker 2
+	swarm_join "token://$TOKEN"
+
+	# Start a manager and ensure it sees all the engines.
+	swarm_manage "token://$TOKEN"
+	check_swarm_nodes
+
+	# Add another engine to the cluster and make sure it's picked up by swarm.
+	start_docker 1
+	swarm_join "token://$TOKEN"
+	retry 10 1 check_swarm_nodes
+}
diff --git a/test/integration/discovery-zk.bats b/test/integration/discovery-zk.bats
new file mode 100644
index 0000000000..638e929fc8
--- /dev/null
+++ b/test/integration/discovery-zk.bats
@@ -0,0 +1,45 @@
+#!/usr/bin/env bats
+
+load helpers
+
+# Address on which Zookeeper will listen (random port between 7000 and 8000).
+ZK_HOST=127.0.0.1:$(( ( RANDOM % 1000 )  + 7000 ))
+
+# Container name for integration test
+ZK_CONTAINER_NAME=swarm_integration_zk
+
+function start_zk() {
+	run docker_host run --name $ZK_CONTAINER_NAME -p $ZK_HOST:2181 -d jplock/zookeeper
+	[ "$status" -eq 0 ]
+}
+
+function stop_zk() {
+	run docker_host rm -f -v $ZK_CONTAINER_NAME
+	[ "$status" -eq 0 ]
+}
+
+function setup() {
+	start_zk
+}
+
+function teardown() {
+	swarm_manage_cleanup
+	swarm_join_cleanup
+	stop_docker
+	stop_zk
+}
+
+@test "zookeeper discovery" {
+	# Start 2 engines and make them join the cluster.
+	start_docker 2
+	swarm_join "zk://${ZK_HOST}/test"
+
+	# Start a manager and ensure it sees all the engines.
+	swarm_manage "zk://${ZK_HOST}/test"
+	check_swarm_nodes
+
+	# Add another engine to the cluster and make sure it's picked up by swarm.
+	start_docker 1
+	swarm_join "zk://${ZK_HOST}/test"
+	retry 30 1 check_swarm_nodes
+}
diff --git a/test/integration/file-discovery.bats b/test/integration/file-discovery.bats
deleted file mode 100644
index d2ca80a658..0000000000
--- a/test/integration/file-discovery.bats
+++ /dev/null
@@ -1,28 +0,0 @@
-#!/usr/bin/env bats
-
-load helpers
-
-# create a blank temp file for discovery
-DISCOVERY_FILE=$(mktemp)
-
-function teardown() {
-	swarm_manage_cleanup
-	rm -f $DISCOVERY_FILE
-	stop_docker
-}
-
-function setup_file_discovery() {
-	for host in ${HOSTS[@]}; do
-		echo "$host" >> $DISCOVERY_FILE
-	done
-}
-
-@test "file discovery" {
-	start_docker 2
-	setup_file_discovery
-	swarm_manage file://$DISCOVERY_FILE
-
-	run docker_swarm info
-	[ "$status" -eq 0 ]
-	[[ "$output" == *"Nodes: 2"* ]]
-}
diff --git a/test/integration/helpers.bash b/test/integration/helpers.bash
index 20263dc39a..dca57a68f3 100644
--- a/test/integration/helpers.bash
+++ b/test/integration/helpers.bash
@@ -75,7 +75,7 @@ function retry() {
 	done
 
 	echo "Command \"$@\" failed $attempts times. Output: $output"
-	[[ false ]]
+	false
 }
 
 # Waits until the given docker engine API becomes reachable.
@@ -83,6 +83,11 @@ function wait_until_reachable() {
 	retry 10 1 docker -H $1 info
 }
 
+# Returns true if all nodes have joined the swarm.
+function check_swarm_nodes() {
+	docker_swarm info | grep -q "Nodes: ${#HOSTS[@]}"
+}
+
 # Start the swarm manager in background.
 function swarm_manage() {
 	local discovery
@@ -92,32 +97,55 @@ function swarm_manage() {
 		discovery="$@"
 	fi
 
-	$SWARM_BINARY manage -H $SWARM_HOST $discovery &
+	"$SWARM_BINARY" manage -H "$SWARM_HOST" --heartbeat=1 "$discovery" &
 	SWARM_PID=$!
-	wait_until_reachable $SWARM_HOST
+	wait_until_reachable "$SWARM_HOST"
+	retry 10 1 check_swarm_nodes
 }
 
-# Start swarm join for every engine with the discovery as parameter
+# swarm join every engine created with `start_docker`.
+#
+# It will wait until all nodes are visible in discovery (`swarm list`) before
+# returning and will fail if that's not the case after a certain time.
+#
+# It can be called multiple times and will only join new engines started with
+# `start_docker` since the last `swarm_join` call.
 function swarm_join() {
-	local i=0
-	for h in ${HOSTS[@]}; do
-		echo "Swarm join #${i}: $h $@"
-		$SWARM_BINARY join --addr=$h "$@" &
+	local current=${#SWARM_JOIN_PID[@]}
+	local nodes=${#HOSTS[@]}
+	local addr="$1"
+	shift
+
+	# Start the engines.
+	local i
+	echo "current: $current | nodes: $nodes" > log
+	for ((i=current; i < nodes; i++)); do
+		local h="${HOSTS[$i]}"
+		echo "Swarm join #${i}: $h $addr"
+		"$SWARM_BINARY" join --addr="$h" "$addr" &
 		SWARM_JOIN_PID[$i]=$!
-		((++i))
 	done
-	retry 30 1 [ -n "$(docker_swarm info | grep -q 'Nodes: $i')" ]
+	retry 10 0.5 check_discovery_nodes "$addr"
+}
+
+# Returns true if all nodes have joined the discovery.
+function check_discovery_nodes() {
+	local joined=`swarm list "$1" | wc -l`
+	local total=${#HOSTS[@]}
+
+	echo "${joined} out of ${total} hosts joined discovery"
+	[ "$joined" -eq "$total" ]
 }
 
 # Stops the manager.
 function swarm_manage_cleanup() {
-	kill $SWARM_PID
+	kill $SWARM_PID || true
 }
 
 # Clean up Swarm join processes
 function swarm_join_cleanup() {
 	for pid in ${SWARM_JOIN_PID[@]}; do
-		kill $pid
+		kill $pid || true
 	done
 }
 
@@ -148,7 +176,7 @@ function start_docker() {
 
 	# Wait for the engines to be reachable.
 	for ((i=current; i < (current + instances); i++)); do
-		wait_until_reachable ${HOSTS[$i]}
+		wait_until_reachable "${HOSTS[$i]}"
 	done
 }
 
diff --git a/test/integration/token-discovery.bats b/test/integration/token-discovery.bats
deleted file mode 100644
index 126424ca20..0000000000
--- a/test/integration/token-discovery.bats
+++ /dev/null
@@ -1,30 +0,0 @@
-#!/usr/bin/env bats
-
-load helpers
-
-function token_cleanup() {
-	curl -X DELETE https://discovery-stage.hub.docker.com/v1/clusters/$1
-}
-
-function teardown() {
-	swarm_join_cleanup
-	swarm_manage_cleanup
-	stop_docker
-}
-
-@test "token discovery" {
-	start_docker 2
-
-	TOKEN=$(swarm create)
-	[ "$status" -eq 0 ]
-	[[ ${TOKEN} =~ ^[0-9a-f]{32}$ ]]
-
-	swarm_manage token://$TOKEN
-	swarm_join   token://$TOKEN
-
-	run docker_swarm info
-	echo $output
-	[[ "$output" == *"Nodes: 2"* ]]
-
-	token_cleanup $TOKEN
-}
diff --git a/test/integration/zk-discovery.bats b/test/integration/zk-discovery.bats
deleted file mode 100644
index c21f3daed7..0000000000
--- a/test/integration/zk-discovery.bats
+++ /dev/null
@@ -1,35 +0,0 @@
-#!/usr/bin/env bats
-
-load helpers
-
-# Address on which Zookeeper will listen (random port between 7000 and 8000).
-ZK_HOST=127.0.0.1:$(( ( RANDOM % 1000 )  + 7000 ))
-
-# Container name for integration test
-ZK_CONTAINER_NAME=swarm_integration_zk
-
-function start_zk() {
-	docker_host run --name $ZK_CONTAINER_NAME -p $ZK_HOST:2181 -d jplock/zookeeper
-}
-
-function stop_zk() {
-	docker_host rm -f -v $ZK_CONTAINER_NAME > /dev/null
-}
-
-function teardown() {
-	swarm_join_cleanup
-	swarm_manage_cleanup
-	stop_docker
-	stop_zk
-}
-
-@test "zk discovery" {
-	start_zk
-	start_docker 1
-
-	swarm_manage zk://${ZK_HOST}/test
-	swarm_join   zk://${ZK_HOST}/test
-
-	run docker_swarm info
-	[[ "$output" == *"Nodes: 1"* ]]
-}