Add RuntimeStatus in container/runtime.go

pkg/kubelet/container/runtime.go

@@ -70,8 +70,9 @@ type Runtime interface {
 	// This may be different from the runtime engine's version.
 	// TODO(random-liu): We should fold this into Version()
 	APIVersion() (Version, error)
-	// Status returns error if the runtime is unhealthy; nil otherwise.
-	Status() error
+	// Status returns the status of the runtime. An error is returned if the Status
+	// function itself fails, nil otherwise.
+	Status() (*RuntimeStatus, error)
 	// GetPods returns a list of containers grouped by pods. The boolean parameter
 	// specifies whether the runtime returns all containers including those already
 	// exited and dead containers (used for garbage collection).
@@ -446,6 +447,59 @@ type VolumeInfo struct {
 
 type VolumeMap map[string]VolumeInfo
 
+// RuntimeConditionType is the types of required runtime conditions.
+type RuntimeConditionType string
+
+const (
+	// RuntimeReady means the runtime is up and ready to accept basic containers.
+	RuntimeReady RuntimeConditionType = "RuntimeReady"
+	// NetworkReady means the runtime network is up and ready to accept containers which require network.
+	NetworkReady RuntimeConditionType = "NetworkReady"
+)
+
+// RuntimeStatus contains the status of the runtime.
+type RuntimeStatus struct {
+	// Conditions is an array of current observed runtime conditions.
+	Conditions []RuntimeCondition
+}
+
+// GetRuntimeCondition gets a specified runtime condition from the runtime status.
+func (r *RuntimeStatus) GetRuntimeCondition(t RuntimeConditionType) *RuntimeCondition {
+	for i := range r.Conditions {
+		c := &r.Conditions[i]
+		if c.Type == t {
+			return c
+		}
+	}
+	return nil
+}
+
+// String formats the runtime status into human readable string.
+func (s *RuntimeStatus) String() string {
+	var ss []string
+	for _, c := range s.Conditions {
+		ss = append(ss, c.String())
+	}
+	return fmt.Sprintf("Runtime Conditions: %s", strings.Join(ss, ", "))
+}
+
+// RuntimeCondition contains condition information for the runtime.
+type RuntimeCondition struct {
+	// Type of runtime condition.
+	Type RuntimeConditionType
+	// Status of the condition, one of true/false.
+	Status bool
+	// Reason is brief reason for the condition's last transition.
+	Reason string
+	// Message is human readable message indicating details about last transition.
+	Message string
+}
+
+// String formats the runtime condition into human readable string.
+func (c *RuntimeCondition) String() string {
+	return fmt.Sprintf("%s=%t reason:%s message:%s", c.Type, c.Status, c.Reason, c.Message)
+}
+
 type Pods []*Pod
 
 // FindPodByID finds and returns a pod in the pod list by UID. It will return an empty pod