Test connection count between swarm manager and nodes.

Signed-off-by: Dong Chen <dongluo.chen@docker.com>

test/integration/nodemanagement/connection.bats

@@ -0,0 +1,41 @@
+#!/usr/bin/env bats
+
+load ../helpers
+
+function teardown() {
+	swarm_manage_cleanup
+	stop_docker
+}
+
+@test "Swarm not leak tcp connections" {
+	# Start engine with busybox image
+	start_docker_with_busybox 2
+	# Start swarm and check it can reach the node
+	swarm_manage --engine-refresh-min-interval "20s" --engine-refresh-max-interval "20s" --engine-failure-retry 20 "${HOSTS[0]},${HOSTS[1]}"
+	eval "docker_swarm info | grep -q -i 'Nodes: 2'"
+
+	# create busybox with host network so that we can get netstat
+	run docker_swarm run -itd --name=busybox0 --net=host -e constraint:node==node-0 busybox sh
+	[ "$status" -eq 0 ]
+	run docker_swarm run -itd --name=busybox1 --net=host -e constraint:node==node-1 busybox sh
+	[ "$status" -eq 0 ]
+
+	# run most common container operations
+	for((i=0; i<30; i++)); do
+		# test postContainerCreate
+		docker_swarm run --name="hello$i" hello-world
+		# test getContainerJSON
+		docker_swarm inspect "hello$i"
+		# test proxyContainer
+		docker_swarm logs "hello$i"
+		# test proxyContainerAndForceRefresh
+		docker_swarm stop "hello$i"
+	done
+
+	# get connection count
+	count0=$(docker_swarm exec busybox0 netstat -an | grep "${HOSTS[0]}" | grep -i "ESTABLISHED" | wc -l)
+	count1=$(docker_swarm exec busybox1 netstat -an | grep "${HOSTS[1]}" | grep -i "ESTABLISHED" | wc -l)
+	[[ "$count0" -le 10 ]]
+	[[ "$count1" -le 10 ]]
+}
+