Merge pull request #300 from damemi/refactor-is-evictable

Add more verbose logging to IsEvictable checks

README.md

@@ -243,6 +243,8 @@ never evicted because these pods won't be recreated.
   annotation is used to override checks which prevent eviction and users can select which pod is evicted.
   Users should know how and if the pod will be recreated.
 
+Setting `--v=4` or greater on the Descheduler will log all reasons why any pod is not evictable.
+
 ### Pod Disruption Budget (PDB)
 
 Pods subject to a Pod Disruption Budget(PDB) are not evicted if descheduling violates its PDB. The pods

pkg/descheduler/pod/pods.go

@@ -18,10 +18,13 @@ package pod
 
 import (
 	"context"
+	"fmt"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/apimachinery/pkg/util/errors"
 	clientset "k8s.io/client-go/kubernetes"
+	"k8s.io/klog"
 	"sigs.k8s.io/descheduler/pkg/utils"
 )
 
@@ -31,8 +34,30 @@ const (
 
 // IsEvictable checks if a pod is evictable or not.
 func IsEvictable(pod *v1.Pod, evictLocalStoragePods bool) bool {
+	checkErrs := []error{}
+	if IsCriticalPod(pod) {
+		checkErrs = append(checkErrs, fmt.Errorf("pod is critical"))
+	}
+
 	ownerRefList := OwnerRef(pod)
-	if !HaveEvictAnnotation(pod) && (IsMirrorPod(pod) || (!evictLocalStoragePods && IsPodWithLocalStorage(pod)) || len(ownerRefList) == 0 || IsDaemonsetPod(ownerRefList) || IsCriticalPod(pod)) {
+	if IsDaemonsetPod(ownerRefList) {
+		checkErrs = append(checkErrs, fmt.Errorf("pod is a DaemonSet pod"))
+	}
+
+	if len(ownerRefList) == 0 {
+		checkErrs = append(checkErrs, fmt.Errorf("pod does not have any ownerrefs"))
+	}
+
+	if !evictLocalStoragePods && IsPodWithLocalStorage(pod) {
+		checkErrs = append(checkErrs, fmt.Errorf("pod has local storage and descheduler is not configured with --evict-local-storage-pods"))
+	}
+
+	if IsMirrorPod(pod) {
+		checkErrs = append(checkErrs, fmt.Errorf("pod is a mirror pod"))
+	}
+
+	if len(checkErrs) > 0 && !HaveEvictAnnotation(pod) {
+		klog.V(4).Infof("Pod %s in namespace %s is not evictable: Pod lacks an eviction annotation and fails the following checks: %v", pod.Name, pod.Namespace, errors.NewAggregate(checkErrs).Error())
 		return false
 	}
 	return true