kubelet: change map[string]RuntimeHandler to []RuntimeHandler

The map is changed to an array so as to retain the order of the original array
propagated from the CRI runtime.

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

pkg/kubelet/container/runtime.go

@@ -530,8 +530,8 @@ const (
 type RuntimeStatus struct {
 	// Conditions is an array of current observed runtime conditions.
 	Conditions []RuntimeCondition
-	// Handlers is a map of current available handlers
+	// Handlers is an array of current available handlers
-	Handlers map[string]RuntimeHandler
+	Handlers []RuntimeHandler
 }
 
 // GetRuntimeCondition gets a specified runtime condition from the runtime status.

pkg/kubelet/kubelet_getters.go

@@ -123,11 +123,12 @@ func (kl *Kubelet) HandlerSupportsUserNamespaces(rtHandler string) (bool, error)
 	if rtHandlers == nil {
 		return false, fmt.Errorf("runtime handlers are not set")
 	}
-	h, found := rtHandlers[rtHandler]
+	for _, h := range rtHandlers {
-	if !found {
+		if h.Name == rtHandler {
-		return false, fmt.Errorf("the handler %q is not known", rtHandler)
+			return h.SupportsUserNamespaces, nil
+		}
 	}
-	return h.SupportsUserNamespaces, nil
+	return false, fmt.Errorf("the handler %q is not known", rtHandler)
 }
 
 // GetKubeletMappings gets the additional IDs allocated for the Kubelet.

pkg/kubelet/kubelet_getters_test.go

@@ -109,13 +109,13 @@ func TestHandlerSupportsUserNamespaces(t *testing.T) {
 	defer testKubelet.Cleanup()
 	kubelet := testKubelet.kubelet
 
-	kubelet.runtimeState.setRuntimeHandlers(map[string]kubecontainer.RuntimeHandler{
+	kubelet.runtimeState.setRuntimeHandlers([]kubecontainer.RuntimeHandler{
-		"has-support": {
+		{
 			Name:                   "has-support",
 			SupportsUserNamespaces: true,
 		},
-		"has-no-support": {
+		{
-			Name:                   "has-support",
+			Name:                   "has-no-support",
 			SupportsUserNamespaces: false,
 		},
 	})

pkg/kubelet/kuberuntime/helpers.go

@@ -219,13 +219,13 @@ func toKubeRuntimeStatus(status *runtimeapi.RuntimeStatus, handlers []*runtimeap
 			Message: c.Message,
 		})
 	}
-	retHandlers := make(map[string]kubecontainer.RuntimeHandler)
+	retHandlers := make([]kubecontainer.RuntimeHandler, len(handlers))
-	for _, h := range handlers {
+	for i, h := range handlers {
 		supportsUserns := false
 		if h.Features != nil {
 			supportsUserns = h.Features.UserNamespaces
 		}
-		retHandlers[h.Name] = kubecontainer.RuntimeHandler{
+		retHandlers[i] = kubecontainer.RuntimeHandler{
 			Name:                   h.Name,
 			SupportsUserNamespaces: supportsUserns,
 		}

pkg/kubelet/runtime.go

@@ -35,7 +35,7 @@ type runtimeState struct {
 	storageError             error
 	cidr                     string
 	healthChecks             []*healthCheck
-	rtHandlers               map[string]kubecontainer.RuntimeHandler
+	rtHandlers               []kubecontainer.RuntimeHandler
 }
 
 // A health check function should be efficient and not rely on external
@@ -71,13 +71,13 @@ func (s *runtimeState) setRuntimeState(err error) {
 	s.runtimeError = err
 }
 
-func (s *runtimeState) setRuntimeHandlers(rtHandlers map[string]kubecontainer.RuntimeHandler) {
+func (s *runtimeState) setRuntimeHandlers(rtHandlers []kubecontainer.RuntimeHandler) {
 	s.Lock()
 	defer s.Unlock()
 	s.rtHandlers = rtHandlers
 }
 
-func (s *runtimeState) runtimeHandlers() map[string]kubecontainer.RuntimeHandler {
+func (s *runtimeState) runtimeHandlers() []kubecontainer.RuntimeHandler {
 	s.RLock()
 	defer s.RUnlock()
 	return s.rtHandlers