moby/integration-cli/docker_api_swarm_service_test.go
Aaron Lehmann 47436e9628 TestAPISwarmServicesUpdateStartFirst: Increase timeout on health check command
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
2017-05-12 10:42:29 -07:00

598 lines
22 KiB
Go

// +build !windows
package main
import (
"fmt"
"strconv"
"strings"
"syscall"
"time"
"github.com/docker/docker/api/types/swarm"
"github.com/docker/docker/integration-cli/checker"
"github.com/docker/docker/integration-cli/daemon"
"github.com/go-check/check"
)
func setPortConfig(portConfig []swarm.PortConfig) daemon.ServiceConstructor {
return func(s *swarm.Service) {
if s.Spec.EndpointSpec == nil {
s.Spec.EndpointSpec = &swarm.EndpointSpec{}
}
s.Spec.EndpointSpec.Ports = portConfig
}
}
func (s *DockerSwarmSuite) TestAPIServiceUpdatePort(c *check.C) {
d := s.AddDaemon(c, true, true)
// Create a service with a port mapping of 8080:8081.
portConfig := []swarm.PortConfig{{TargetPort: 8081, PublishedPort: 8080}}
serviceID := d.CreateService(c, simpleTestService, setInstances(1), setPortConfig(portConfig))
waitAndAssert(c, defaultReconciliationTimeout, d.CheckActiveContainerCount, checker.Equals, 1)
// Update the service: changed the port mapping from 8080:8081 to 8082:8083.
updatedPortConfig := []swarm.PortConfig{{TargetPort: 8083, PublishedPort: 8082}}
remoteService := d.GetService(c, serviceID)
d.UpdateService(c, remoteService, setPortConfig(updatedPortConfig))
// Inspect the service and verify port mapping.
updatedService := d.GetService(c, serviceID)
c.Assert(updatedService.Spec.EndpointSpec, check.NotNil)
c.Assert(len(updatedService.Spec.EndpointSpec.Ports), check.Equals, 1)
c.Assert(updatedService.Spec.EndpointSpec.Ports[0].TargetPort, check.Equals, uint32(8083))
c.Assert(updatedService.Spec.EndpointSpec.Ports[0].PublishedPort, check.Equals, uint32(8082))
}
func (s *DockerSwarmSuite) TestAPISwarmServicesEmptyList(c *check.C) {
d := s.AddDaemon(c, true, true)
services := d.ListServices(c)
c.Assert(services, checker.NotNil)
c.Assert(len(services), checker.Equals, 0, check.Commentf("services: %#v", services))
}
func (s *DockerSwarmSuite) TestAPISwarmServicesCreate(c *check.C) {
d := s.AddDaemon(c, true, true)
instances := 2
id := d.CreateService(c, simpleTestService, setInstances(instances))
waitAndAssert(c, defaultReconciliationTimeout, d.CheckActiveContainerCount, checker.Equals, instances)
// insertDefaults inserts UpdateConfig when service is fetched by ID
_, out, err := d.SockRequest("GET", "/services/"+id+"?insertDefaults=true", nil)
c.Assert(err, checker.IsNil, check.Commentf("%s", out))
c.Assert(string(out), checker.Contains, "UpdateConfig")
// insertDefaults inserts UpdateConfig when service is fetched by ID
_, out, err = d.SockRequest("GET", "/services/top?insertDefaults=true", nil)
c.Assert(err, checker.IsNil, check.Commentf("%s", out))
c.Assert(string(out), checker.Contains, "UpdateConfig")
service := d.GetService(c, id)
instances = 5
d.UpdateService(c, service, setInstances(instances))
waitAndAssert(c, defaultReconciliationTimeout, d.CheckActiveContainerCount, checker.Equals, instances)
d.RemoveService(c, service.ID)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckActiveContainerCount, checker.Equals, 0)
}
func (s *DockerSwarmSuite) TestAPISwarmServicesMultipleAgents(c *check.C) {
d1 := s.AddDaemon(c, true, true)
d2 := s.AddDaemon(c, true, false)
d3 := s.AddDaemon(c, true, false)
time.Sleep(1 * time.Second) // make sure all daemons are ready to accept tasks
instances := 9
id := d1.CreateService(c, simpleTestService, setInstances(instances))
waitAndAssert(c, defaultReconciliationTimeout, d1.CheckActiveContainerCount, checker.GreaterThan, 0)
waitAndAssert(c, defaultReconciliationTimeout, d2.CheckActiveContainerCount, checker.GreaterThan, 0)
waitAndAssert(c, defaultReconciliationTimeout, d3.CheckActiveContainerCount, checker.GreaterThan, 0)
waitAndAssert(c, defaultReconciliationTimeout, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d2.CheckActiveContainerCount, d3.CheckActiveContainerCount), checker.Equals, instances)
// reconciliation on d2 node down
d2.Stop(c)
waitAndAssert(c, defaultReconciliationTimeout, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d3.CheckActiveContainerCount), checker.Equals, instances)
// test downscaling
instances = 5
d1.UpdateService(c, d1.GetService(c, id), setInstances(instances))
waitAndAssert(c, defaultReconciliationTimeout, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d3.CheckActiveContainerCount), checker.Equals, instances)
}
func (s *DockerSwarmSuite) TestAPISwarmServicesCreateGlobal(c *check.C) {
d1 := s.AddDaemon(c, true, true)
d2 := s.AddDaemon(c, true, false)
d3 := s.AddDaemon(c, true, false)
d1.CreateService(c, simpleTestService, setGlobalMode)
waitAndAssert(c, defaultReconciliationTimeout, d1.CheckActiveContainerCount, checker.Equals, 1)
waitAndAssert(c, defaultReconciliationTimeout, d2.CheckActiveContainerCount, checker.Equals, 1)
waitAndAssert(c, defaultReconciliationTimeout, d3.CheckActiveContainerCount, checker.Equals, 1)
d4 := s.AddDaemon(c, true, false)
d5 := s.AddDaemon(c, true, false)
waitAndAssert(c, defaultReconciliationTimeout, d4.CheckActiveContainerCount, checker.Equals, 1)
waitAndAssert(c, defaultReconciliationTimeout, d5.CheckActiveContainerCount, checker.Equals, 1)
}
func (s *DockerSwarmSuite) TestAPISwarmServicesUpdate(c *check.C) {
const nodeCount = 3
var daemons [nodeCount]*daemon.Swarm
for i := 0; i < nodeCount; i++ {
daemons[i] = s.AddDaemon(c, true, i == 0)
}
// wait for nodes ready
waitAndAssert(c, 5*time.Second, daemons[0].CheckNodeReadyCount, checker.Equals, nodeCount)
// service image at start
image1 := "busybox:latest"
// target image in update
image2 := "busybox:test"
// create a different tag
for _, d := range daemons {
out, err := d.Cmd("tag", image1, image2)
c.Assert(err, checker.IsNil, check.Commentf(out))
}
// create service
instances := 5
parallelism := 2
rollbackParallelism := 3
id := daemons[0].CreateService(c, serviceForUpdate, setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
// issue service update
service := daemons[0].GetService(c, id)
daemons[0].UpdateService(c, service, setImage(image2))
// first batch
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances - parallelism, image2: parallelism})
// 2nd batch
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances - 2*parallelism, image2: 2 * parallelism})
// 3nd batch
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image2: instances})
// Roll back to the previous version. This uses the CLI because
// rollback used to be a client-side operation.
out, err := daemons[0].Cmd("service", "update", "--rollback", id)
c.Assert(err, checker.IsNil, check.Commentf(out))
// first batch
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image2: instances - rollbackParallelism, image1: rollbackParallelism})
// 2nd batch
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
}
func (s *DockerSwarmSuite) TestAPISwarmServicesUpdateStartFirst(c *check.C) {
d := s.AddDaemon(c, true, true)
// service image at start
image1 := "busybox:latest"
// target image in update
image2 := "testhealth"
// service started from this image won't pass health check
_, _, err := d.BuildImageWithOut(image2,
`FROM busybox
HEALTHCHECK --interval=1s --timeout=30s --retries=1024 \
CMD cat /status`,
true)
c.Check(err, check.IsNil)
// create service
instances := 5
parallelism := 2
rollbackParallelism := 3
id := d.CreateService(c, serviceForUpdate, setInstances(instances), setUpdateOrder(swarm.UpdateOrderStartFirst), setRollbackOrder(swarm.UpdateOrderStartFirst))
checkStartingTasks := func(expected int) []swarm.Task {
var startingTasks []swarm.Task
waitAndAssert(c, defaultReconciliationTimeout, func(c *check.C) (interface{}, check.CommentInterface) {
tasks := d.GetServiceTasks(c, id)
startingTasks = nil
for _, t := range tasks {
if t.Status.State == swarm.TaskStateStarting {
startingTasks = append(startingTasks, t)
}
}
return startingTasks, nil
}, checker.HasLen, expected)
return startingTasks
}
makeTasksHealthy := func(tasks []swarm.Task) {
for _, t := range tasks {
containerID := t.Status.ContainerStatus.ContainerID
d.Cmd("exec", containerID, "touch", "/status")
}
}
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
// issue service update
service := d.GetService(c, id)
d.UpdateService(c, service, setImage(image2))
// first batch
// The old tasks should be running, and the new ones should be starting.
startingTasks := checkStartingTasks(parallelism)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
// make it healthy
makeTasksHealthy(startingTasks)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances - parallelism, image2: parallelism})
// 2nd batch
// The old tasks should be running, and the new ones should be starting.
startingTasks = checkStartingTasks(parallelism)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances - parallelism, image2: parallelism})
// make it healthy
makeTasksHealthy(startingTasks)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances - 2*parallelism, image2: 2 * parallelism})
// 3nd batch
// The old tasks should be running, and the new ones should be starting.
startingTasks = checkStartingTasks(1)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances - 2*parallelism, image2: 2 * parallelism})
// make it healthy
makeTasksHealthy(startingTasks)
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image2: instances})
// Roll back to the previous version. This uses the CLI because
// rollback is a client-side operation.
out, err := d.Cmd("service", "update", "--rollback", id)
c.Assert(err, checker.IsNil, check.Commentf(out))
// first batch
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image2: instances - rollbackParallelism, image1: rollbackParallelism})
// 2nd batch
waitAndAssert(c, defaultReconciliationTimeout, d.CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
}
func (s *DockerSwarmSuite) TestAPISwarmServicesFailedUpdate(c *check.C) {
const nodeCount = 3
var daemons [nodeCount]*daemon.Swarm
for i := 0; i < nodeCount; i++ {
daemons[i] = s.AddDaemon(c, true, i == 0)
}
// wait for nodes ready
waitAndAssert(c, 5*time.Second, daemons[0].CheckNodeReadyCount, checker.Equals, nodeCount)
// service image at start
image1 := "busybox:latest"
// target image in update
image2 := "busybox:badtag"
// create service
instances := 5
id := daemons[0].CreateService(c, serviceForUpdate, setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
// issue service update
service := daemons[0].GetService(c, id)
daemons[0].UpdateService(c, service, setImage(image2), setFailureAction(swarm.UpdateFailureActionPause), setMaxFailureRatio(0.25), setParallelism(1))
// should update 2 tasks and then pause
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceUpdateState(id), checker.Equals, swarm.UpdateStatePaused)
v, _ := daemons[0].CheckServiceRunningTasks(id)(c)
c.Assert(v, checker.Equals, instances-2)
// Roll back to the previous version. This uses the CLI because
// rollback used to be a client-side operation.
out, err := daemons[0].Cmd("service", "update", "--rollback", id)
c.Assert(err, checker.IsNil, check.Commentf(out))
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckRunningTaskImages, checker.DeepEquals,
map[string]int{image1: instances})
}
func (s *DockerSwarmSuite) TestAPISwarmServiceConstraintRole(c *check.C) {
const nodeCount = 3
var daemons [nodeCount]*daemon.Swarm
for i := 0; i < nodeCount; i++ {
daemons[i] = s.AddDaemon(c, true, i == 0)
}
// wait for nodes ready
waitAndAssert(c, 5*time.Second, daemons[0].CheckNodeReadyCount, checker.Equals, nodeCount)
// create service
constraints := []string{"node.role==worker"}
instances := 3
id := daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceRunningTasks(id), checker.Equals, instances)
// validate tasks are running on worker nodes
tasks := daemons[0].GetServiceTasks(c, id)
for _, task := range tasks {
node := daemons[0].GetNode(c, task.NodeID)
c.Assert(node.Spec.Role, checker.Equals, swarm.NodeRoleWorker)
}
//remove service
daemons[0].RemoveService(c, id)
// create service
constraints = []string{"node.role!=worker"}
id = daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceRunningTasks(id), checker.Equals, instances)
tasks = daemons[0].GetServiceTasks(c, id)
// validate tasks are running on manager nodes
for _, task := range tasks {
node := daemons[0].GetNode(c, task.NodeID)
c.Assert(node.Spec.Role, checker.Equals, swarm.NodeRoleManager)
}
//remove service
daemons[0].RemoveService(c, id)
// create service
constraints = []string{"node.role==nosuchrole"}
id = daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks created
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceTasks(id), checker.Equals, instances)
// let scheduler try
time.Sleep(250 * time.Millisecond)
// validate tasks are not assigned to any node
tasks = daemons[0].GetServiceTasks(c, id)
for _, task := range tasks {
c.Assert(task.NodeID, checker.Equals, "")
}
}
func (s *DockerSwarmSuite) TestAPISwarmServiceConstraintLabel(c *check.C) {
const nodeCount = 3
var daemons [nodeCount]*daemon.Swarm
for i := 0; i < nodeCount; i++ {
daemons[i] = s.AddDaemon(c, true, i == 0)
}
// wait for nodes ready
waitAndAssert(c, 5*time.Second, daemons[0].CheckNodeReadyCount, checker.Equals, nodeCount)
nodes := daemons[0].ListNodes(c)
c.Assert(len(nodes), checker.Equals, nodeCount)
// add labels to nodes
daemons[0].UpdateNode(c, nodes[0].ID, func(n *swarm.Node) {
n.Spec.Annotations.Labels = map[string]string{
"security": "high",
}
})
for i := 1; i < nodeCount; i++ {
daemons[0].UpdateNode(c, nodes[i].ID, func(n *swarm.Node) {
n.Spec.Annotations.Labels = map[string]string{
"security": "low",
}
})
}
// create service
instances := 3
constraints := []string{"node.labels.security==high"}
id := daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceRunningTasks(id), checker.Equals, instances)
tasks := daemons[0].GetServiceTasks(c, id)
// validate all tasks are running on nodes[0]
for _, task := range tasks {
c.Assert(task.NodeID, checker.Equals, nodes[0].ID)
}
//remove service
daemons[0].RemoveService(c, id)
// create service
constraints = []string{"node.labels.security!=high"}
id = daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceRunningTasks(id), checker.Equals, instances)
tasks = daemons[0].GetServiceTasks(c, id)
// validate all tasks are NOT running on nodes[0]
for _, task := range tasks {
c.Assert(task.NodeID, checker.Not(checker.Equals), nodes[0].ID)
}
//remove service
daemons[0].RemoveService(c, id)
constraints = []string{"node.labels.security==medium"}
id = daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks created
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceTasks(id), checker.Equals, instances)
// let scheduler try
time.Sleep(250 * time.Millisecond)
tasks = daemons[0].GetServiceTasks(c, id)
// validate tasks are not assigned
for _, task := range tasks {
c.Assert(task.NodeID, checker.Equals, "")
}
//remove service
daemons[0].RemoveService(c, id)
// multiple constraints
constraints = []string{
"node.labels.security==high",
fmt.Sprintf("node.id==%s", nodes[1].ID),
}
id = daemons[0].CreateService(c, simpleTestService, setConstraints(constraints), setInstances(instances))
// wait for tasks created
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceTasks(id), checker.Equals, instances)
// let scheduler try
time.Sleep(250 * time.Millisecond)
tasks = daemons[0].GetServiceTasks(c, id)
// validate tasks are not assigned
for _, task := range tasks {
c.Assert(task.NodeID, checker.Equals, "")
}
// make nodes[1] fulfills the constraints
daemons[0].UpdateNode(c, nodes[1].ID, func(n *swarm.Node) {
n.Spec.Annotations.Labels = map[string]string{
"security": "high",
}
})
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceRunningTasks(id), checker.Equals, instances)
tasks = daemons[0].GetServiceTasks(c, id)
for _, task := range tasks {
c.Assert(task.NodeID, checker.Equals, nodes[1].ID)
}
}
func (s *DockerSwarmSuite) TestAPISwarmServicePlacementPrefs(c *check.C) {
const nodeCount = 3
var daemons [nodeCount]*daemon.Swarm
for i := 0; i < nodeCount; i++ {
daemons[i] = s.AddDaemon(c, true, i == 0)
}
// wait for nodes ready
waitAndAssert(c, 5*time.Second, daemons[0].CheckNodeReadyCount, checker.Equals, nodeCount)
nodes := daemons[0].ListNodes(c)
c.Assert(len(nodes), checker.Equals, nodeCount)
// add labels to nodes
daemons[0].UpdateNode(c, nodes[0].ID, func(n *swarm.Node) {
n.Spec.Annotations.Labels = map[string]string{
"rack": "a",
}
})
for i := 1; i < nodeCount; i++ {
daemons[0].UpdateNode(c, nodes[i].ID, func(n *swarm.Node) {
n.Spec.Annotations.Labels = map[string]string{
"rack": "b",
}
})
}
// create service
instances := 4
prefs := []swarm.PlacementPreference{{Spread: &swarm.SpreadOver{SpreadDescriptor: "node.labels.rack"}}}
id := daemons[0].CreateService(c, simpleTestService, setPlacementPrefs(prefs), setInstances(instances))
// wait for tasks ready
waitAndAssert(c, defaultReconciliationTimeout, daemons[0].CheckServiceRunningTasks(id), checker.Equals, instances)
tasks := daemons[0].GetServiceTasks(c, id)
// validate all tasks are running on nodes[0]
tasksOnNode := make(map[string]int)
for _, task := range tasks {
tasksOnNode[task.NodeID]++
}
c.Assert(tasksOnNode[nodes[0].ID], checker.Equals, 2)
c.Assert(tasksOnNode[nodes[1].ID], checker.Equals, 1)
c.Assert(tasksOnNode[nodes[2].ID], checker.Equals, 1)
}
func (s *DockerSwarmSuite) TestAPISwarmServicesStateReporting(c *check.C) {
testRequires(c, SameHostDaemon)
testRequires(c, DaemonIsLinux)
d1 := s.AddDaemon(c, true, true)
d2 := s.AddDaemon(c, true, true)
d3 := s.AddDaemon(c, true, false)
time.Sleep(1 * time.Second) // make sure all daemons are ready to accept
instances := 9
d1.CreateService(c, simpleTestService, setInstances(instances))
waitAndAssert(c, defaultReconciliationTimeout, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d2.CheckActiveContainerCount, d3.CheckActiveContainerCount), checker.Equals, instances)
getContainers := func() map[string]*daemon.Swarm {
m := make(map[string]*daemon.Swarm)
for _, d := range []*daemon.Swarm{d1, d2, d3} {
for _, id := range d.ActiveContainers() {
m[id] = d
}
}
return m
}
containers := getContainers()
c.Assert(containers, checker.HasLen, instances)
var toRemove string
for i := range containers {
toRemove = i
}
_, err := containers[toRemove].Cmd("stop", toRemove)
c.Assert(err, checker.IsNil)
waitAndAssert(c, defaultReconciliationTimeout, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d2.CheckActiveContainerCount, d3.CheckActiveContainerCount), checker.Equals, instances)
containers2 := getContainers()
c.Assert(containers2, checker.HasLen, instances)
for i := range containers {
if i == toRemove {
c.Assert(containers2[i], checker.IsNil)
} else {
c.Assert(containers2[i], checker.NotNil)
}
}
containers = containers2
for i := range containers {
toRemove = i
}
// try with killing process outside of docker
pidStr, err := containers[toRemove].Cmd("inspect", "-f", "{{.State.Pid}}", toRemove)
c.Assert(err, checker.IsNil)
pid, err := strconv.Atoi(strings.TrimSpace(pidStr))
c.Assert(err, checker.IsNil)
c.Assert(syscall.Kill(pid, syscall.SIGKILL), checker.IsNil)
time.Sleep(time.Second) // give some time to handle the signal
waitAndAssert(c, defaultReconciliationTimeout, reducedCheck(sumAsIntegers, d1.CheckActiveContainerCount, d2.CheckActiveContainerCount, d3.CheckActiveContainerCount), checker.Equals, instances)
containers2 = getContainers()
c.Assert(containers2, checker.HasLen, instances)
for i := range containers {
if i == toRemove {
c.Assert(containers2[i], checker.IsNil)
} else {
c.Assert(containers2[i], checker.NotNil)
}
}
}