TODO: move predicate check into a pod admitter

pkg/kubelet/lifecycle/predicate.go

@@ -0,0 +1,107 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package lifecycle
+
+import (
+	"fmt"
+
+	"github.com/golang/glog"
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/kubelet/util/format"
+	"k8s.io/kubernetes/plugin/pkg/scheduler/algorithm/predicates"
+	"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
+)
+
+type getNodeAnyWayFuncType func() (*api.Node, error)
+type predicateAdmitHandler struct {
+	getNodeAnyWayFunc getNodeAnyWayFuncType
+}
+
+var _ PodAdmitHandler = &predicateAdmitHandler{}
+
+func NewPredicateAdmitHandler(getNodeAnyWayFunc getNodeAnyWayFuncType) *predicateAdmitHandler {
+	return &predicateAdmitHandler{
+		getNodeAnyWayFunc,
+	}
+}
+
+func (w *predicateAdmitHandler) Admit(attrs *PodAdmitAttributes) PodAdmitResult {
+	node, err := w.getNodeAnyWayFunc()
+	if err != nil {
+		glog.Errorf("Cannot get Node info: %v", err)
+		return PodAdmitResult{
+			Admit:   false,
+			Reason:  "InvalidNodeInfo",
+			Message: "Kubelet cannot get node info.",
+		}
+	}
+	pod := attrs.Pod
+	pods := attrs.OtherPods
+	nodeInfo := schedulercache.NewNodeInfo(pods...)
+	nodeInfo.SetNode(node)
+	fit, reasons, err := predicates.GeneralPredicates(pod, nil, nodeInfo)
+	if err != nil {
+		message := fmt.Sprintf("GeneralPredicates failed due to %v, which is unexpected.", err)
+		glog.Warningf("Failed to admit pod %v - %s", format.Pod(pod), message)
+		return PodAdmitResult{
+			Admit:   fit,
+			Reason:  "UnexpectedError",
+			Message: message,
+		}
+	}
+	if !fit {
+		var reason string
+		var message string
+		if len(reasons) == 0 {
+			message = fmt.Sprint("GeneralPredicates failed due to unknown reason, which is unexpected.")
+			glog.Warningf("Failed to admit pod %v - %s", format.Pod(pod), message)
+			return PodAdmitResult{
+				Admit:   fit,
+				Reason:  "UnknownReason",
+				Message: message,
+			}
+		}
+		// If there are failed predicates, we only return the first one as a reason.
+		r := reasons[0]
+		switch re := r.(type) {
+		case *predicates.PredicateFailureError:
+			reason = re.PredicateName
+			message = re.Error()
+			glog.V(2).Infof("Predicate failed on Pod: %v, for reason: %v", format.Pod(pod), message)
+		case *predicates.InsufficientResourceError:
+			reason = fmt.Sprintf("OutOf%s", re.ResourceName)
+			message := re.Error()
+			glog.V(2).Infof("Predicate failed on Pod: %v, for reason: %v", format.Pod(pod), message)
+		case *predicates.FailureReason:
+			reason = re.GetReason()
+			message = fmt.Sprintf("Failure: %s", re.GetReason())
+			glog.V(2).Infof("Predicate failed on Pod: %v, for reason: %v", format.Pod(pod), message)
+		default:
+			reason = "UnexpectedPredicateFailureType"
+			message := fmt.Sprintf("GeneralPredicates failed due to %v, which is unexpected.", r)
+			glog.Warningf("Failed to admit pod %v - %s", format.Pod(pod), message)
+		}
+		return PodAdmitResult{
+			Admit:   fit,
+			Reason:  reason,
+			Message: message,
+		}
+	}
+	return PodAdmitResult{
+		Admit: true,
+	}
+}