[kubeadm/app/util]switch to github.com/pkg/errors

Signed-off-by: yuexiao-wang <wang.yuexiao@zte.com.cn>

cmd/kubeadm/app/phases/upgrade/BUILD

@@ -49,6 +49,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/version:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//staging/src/k8s.io/client-go/util/cert:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/phases/upgrade/health.go

@@ -21,6 +21,8 @@ import (
 	"net/http"
 	"os"
 
+	"github.com/pkg/errors"
+
 	apps "k8s.io/api/apps/v1"
 	"k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -116,11 +118,11 @@ func masterNodesReady(client clientset.Interface) error {
 		LabelSelector: selector.String(),
 	})
 	if err != nil {
-		return fmt.Errorf("couldn't list masters in cluster: %v", err)
+		return errors.Wrap(err, "couldn't list masters in cluster")
 	}
 
 	if len(masters.Items) == 0 {
-		return fmt.Errorf("failed to find any nodes with master role")
+		return errors.New("failed to find any nodes with master role")
 	}
 
 	notReadyMasters := getNotReadyNodes(masters.Items)
@@ -192,10 +194,10 @@ func daemonSetHealth(dsStatus *apps.DaemonSetStatus) error {
 		return fmt.Errorf("current number of scheduled Pods ('%d') doesn't match the amount of desired Pods ('%d')", dsStatus.CurrentNumberScheduled, dsStatus.DesiredNumberScheduled)
 	}
 	if dsStatus.NumberAvailable == 0 {
-		return fmt.Errorf("no available Pods for DaemonSet")
+		return errors.New("no available Pods for DaemonSet")
 	}
 	if dsStatus.NumberReady == 0 {
-		return fmt.Errorf("no ready Pods for DaemonSet")
+		return errors.New("no ready Pods for DaemonSet")
 	}
 	return nil
 }

cmd/kubeadm/app/phases/upgrade/staticpods.go

@@ -22,6 +22,8 @@ import (
 	"strings"
 	"time"
 
+	"github.com/pkg/errors"
+
 	"k8s.io/apimachinery/pkg/util/version"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
@@ -253,30 +255,30 @@ func upgradeComponent(component string, waiter apiclient.Waiter, pathMgr StaticP
 func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathManager, cfg *kubeadmapi.InitConfiguration, recoverManifests map[string]string, isTLSUpgrade bool, oldEtcdClient, newEtcdClient etcdutil.ClusterInterrogator) (bool, error) {
 	// Add etcd static pod spec only if external etcd is not configured
 	if cfg.Etcd.External != nil {
-		return false, fmt.Errorf("external etcd detected, won't try to change any etcd state")
+		return false, errors.New("external etcd detected, won't try to change any etcd state")
 	}
 
 	// Checking health state of etcd before proceeding with the upgrade
 	_, err := oldEtcdClient.GetClusterStatus()
 	if err != nil {
-		return true, fmt.Errorf("etcd cluster is not healthy: %v", err)
+		return true, errors.Wrap(err, "etcd cluster is not healthy")
 	}
 
 	// Backing up etcd data store
 	backupEtcdDir := pathMgr.BackupEtcdDir()
 	runningEtcdDir := cfg.Etcd.Local.DataDir
 	if err := util.CopyDir(runningEtcdDir, backupEtcdDir); err != nil {
-		return true, fmt.Errorf("failed to back up etcd data: %v", err)
+		return true, errors.Wrap(err, "failed to back up etcd data")
 	}
 
 	// Need to check currently used version and version from constants, if differs then upgrade
 	desiredEtcdVersion, err := constants.EtcdSupportedVersion(cfg.KubernetesVersion)
 	if err != nil {
-		return true, fmt.Errorf("failed to retrieve an etcd version for the target kubernetes version: %v", err)
+		return true, errors.Wrap(err, "failed to retrieve an etcd version for the target kubernetes version")
 	}
 	currentEtcdVersionStr, err := oldEtcdClient.GetVersion()
 	if err != nil {
-		return true, fmt.Errorf("failed to retrieve the current etcd version: %v", err)
+		return true, errors.Wrap(err, "failed to retrieve the current etcd version")
 	}
 	currentEtcdVersion, err := version.ParseSemantic(currentEtcdVersionStr)
 	if err != nil {
@@ -294,13 +296,13 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 
 	beforeEtcdPodHash, err := waiter.WaitForStaticPodSingleHash(cfg.NodeRegistration.Name, constants.Etcd)
 	if err != nil {
-		return true, fmt.Errorf("failed to get etcd pod's hash: %v", err)
+		return true, errors.Wrap(err, "failed to get etcd pod's hash")
 	}
 
 	// Write the updated etcd static Pod manifest into the temporary directory, at this point no etcd change
 	// has occurred in any aspects.
 	if err := etcdphase.CreateLocalEtcdStaticPodManifestFile(pathMgr.TempManifestDir(), cfg); err != nil {
-		return true, fmt.Errorf("error creating local etcd static pod manifest file: %v", err)
+		return true, errors.Wrap(err, "error creating local etcd static pod manifest file")
 	}
 
 	// Waiter configurations for checking etcd status
@@ -346,7 +348,7 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 		fmt.Println("[upgrade/etcd] Etcd was rolled back and is now available")
 
 		// Since etcd cluster came back up with the old manifest
-		return true, fmt.Errorf("fatal error when trying to upgrade the etcd cluster: %v, rolled the state back to pre-upgrade state", err)
+		return true, errors.Wrap(err, "fatal error when trying to upgrade the etcd cluster, rolled the state back to pre-upgrade state")
 	}
 
 	// Initialize the new etcd client if it wasn't pre-initialized
@@ -357,7 +359,7 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 			cfg.CertificatesDir,
 		)
 		if err != nil {
-			return true, fmt.Errorf("fatal error creating etcd client: %v", err)
+			return true, errors.Wrap(err, "fatal error creating etcd client")
 		}
 		newEtcdClient = client
 	}
@@ -390,7 +392,7 @@ func performEtcdStaticPodUpgrade(waiter apiclient.Waiter, pathMgr StaticPodPathM
 		fmt.Println("[upgrade/etcd] Etcd was rolled back and is now available")
 
 		// We've successfully rolled back etcd, and now return an error describing that the upgrade failed
-		return true, fmt.Errorf("fatal error upgrading local etcd cluster: %v, rolled the state back to pre-upgrade state", err)
+		return true, errors.Wrap(err, "fatal error upgrading local etcd cluster, rolled the state back to pre-upgrade state")
 	}
 
 	return false, nil
@@ -418,7 +420,7 @@ func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager
 				cfg.Etcd.External.KeyFile,
 			)
 			if err != nil {
-				return fmt.Errorf("failed to create etcd client for external etcd: %v", err)
+				return errors.Wrap(err, "failed to create etcd client for external etcd")
 			}
 			oldEtcdClient = client
 			// Since etcd is managed externally, the new etcd client will be the same as the old client
@@ -433,7 +435,7 @@ func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager
 				cfg.CertificatesDir,
 			)
 			if err != nil {
-				return fmt.Errorf("failed to create etcd client: %v", err)
+				return errors.Wrap(err, "failed to create etcd client")
 			}
 			oldEtcdClient = client
 		}
@@ -463,7 +465,7 @@ func StaticPodControlPlane(waiter apiclient.Waiter, pathMgr StaticPodPathManager
 	fmt.Printf("[upgrade/staticpods] Writing new Static Pod manifests to %q\n", pathMgr.TempManifestDir())
 	err = controlplanephase.CreateInitStaticPodManifestFiles(pathMgr.TempManifestDir(), cfg)
 	if err != nil {
-		return fmt.Errorf("error creating init static pod manifest files: %v", err)
+		return errors.Wrap(err, "error creating init static pod manifest files")
 	}
 
 	for _, component := range constants.MasterComponents {
@@ -497,7 +499,7 @@ func rollbackOldManifests(oldManifests map[string]string, origErr error, pathMgr
 		}
 	}
 	// Let the user know there were problems, but we tried to recover
-	return fmt.Errorf("couldn't upgrade control plane. kubeadm has tried to recover everything into the earlier state. Errors faced: %v", errs)
+	return errors.New("couldn't upgrade control plane. kubeadm has tried to recover everything into the earlier state. Errors faced")
 }
 
 // rollbackEtcdData rolls back the content of etcd folder if something went wrong.

cmd/kubeadm/app/phases/upgrade/versiongetter.go

@@ -20,6 +20,8 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/pkg/errors"
+
 	"k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	versionutil "k8s.io/apimachinery/pkg/util/version"
@@ -59,13 +61,13 @@ func NewKubeVersionGetter(client clientset.Interface, writer io.Writer) VersionG
 func (g *KubeVersionGetter) ClusterVersion() (string, *versionutil.Version, error) {
 	clusterVersionInfo, err := g.client.Discovery().ServerVersion()
 	if err != nil {
-		return "", nil, fmt.Errorf("Couldn't fetch cluster version from the API Server: %v", err)
+		return "", nil, errors.Wrap(err, "Couldn't fetch cluster version from the API Server")
 	}
 	fmt.Fprintf(g.w, "[upgrade/versions] Cluster version: %s\n", clusterVersionInfo.String())
 
 	clusterVersion, err := versionutil.ParseSemantic(clusterVersionInfo.String())
 	if err != nil {
-		return "", nil, fmt.Errorf("Couldn't parse cluster version: %v", err)
+		return "", nil, errors.Wrap(err, "Couldn't parse cluster version")
 	}
 	return clusterVersionInfo.String(), clusterVersion, nil
 }
@@ -77,7 +79,7 @@ func (g *KubeVersionGetter) KubeadmVersion() (string, *versionutil.Version, erro
 
 	kubeadmVersion, err := versionutil.ParseSemantic(kubeadmVersionInfo.String())
 	if err != nil {
-		return "", nil, fmt.Errorf("Couldn't parse kubeadm version: %v", err)
+		return "", nil, errors.Wrap(err, "Couldn't parse kubeadm version")
 	}
 	return kubeadmVersionInfo.String(), kubeadmVersion, nil
 }
@@ -104,7 +106,7 @@ func (g *KubeVersionGetter) VersionFromCILabel(ciVersionLabel, description strin
 func (g *KubeVersionGetter) KubeletVersions() (map[string]uint16, error) {
 	nodes, err := g.client.CoreV1().Nodes().List(metav1.ListOptions{})
 	if err != nil {
-		return nil, fmt.Errorf("couldn't list all nodes in cluster")
+		return nil, errors.New("couldn't list all nodes in cluster")
 	}
 	return computeKubeletVersions(nodes.Items), nil
 }

cmd/kubeadm/app/util/BUILD

@@ -36,6 +36,7 @@ go_library(
         "//staging/src/k8s.io/client-go/kubernetes/scheme:go_default_library",
         "//vendor/github.com/ghodss/yaml:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
         "//vendor/k8s.io/utils/exec:go_default_library",
     ],
 )

cmd/kubeadm/app/util/apiclient/BUILD

@@ -41,6 +41,7 @@ go_library(
         "//staging/src/k8s.io/client-go/rest:go_default_library",
         "//staging/src/k8s.io/client-go/testing:go_default_library",
         "//staging/src/k8s.io/client-go/tools/clientcmd:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/util/apiclient/clientbacked_dryrun.go

@@ -29,6 +29,8 @@ import (
 	"k8s.io/client-go/rest"
 	core "k8s.io/client-go/testing"
 	"k8s.io/client-go/tools/clientcmd"
+
+	"github.com/pkg/errors"
 )
 
 // ClientBackedDryRunGetter implements the DryRunGetter interface for use in NewDryRunClient() and proxies all GET and LIST requests to the backing API server reachable via rest.Config
@@ -61,11 +63,11 @@ func NewClientBackedDryRunGetter(config *rest.Config) (*ClientBackedDryRunGetter
 func NewClientBackedDryRunGetterFromKubeconfig(file string) (*ClientBackedDryRunGetter, error) {
 	config, err := clientcmd.LoadFromFile(file)
 	if err != nil {
-		return nil, fmt.Errorf("failed to load kubeconfig: %v", err)
+		return nil, errors.Wrap(err, "failed to load kubeconfig")
 	}
 	clientConfig, err := clientcmd.NewDefaultClientConfig(*config, &clientcmd.ConfigOverrides{}).ClientConfig()
 	if err != nil {
-		return nil, fmt.Errorf("failed to create API client configuration from kubeconfig: %v", err)
+		return nil, errors.Wrap(err, "failed to create API client configuration from kubeconfig")
 	}
 	return NewClientBackedDryRunGetter(clientConfig)
 }

cmd/kubeadm/app/util/apiclient/dryrunclient.go

@@ -23,6 +23,7 @@ import (
 	"io"
 	"strings"
 
+	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	clientset "k8s.io/client-go/kubernetes"
@@ -114,7 +115,7 @@ func NewDryRunClientWithOpts(opts DryRunClientOptions) clientset.Interface {
 				getAction, ok := action.(core.GetAction)
 				if !ok {
 					// something's wrong, we can't handle this event
-					return true, nil, fmt.Errorf("can't cast get reactor event action object to GetAction interface")
+					return true, nil, errors.New("can't cast get reactor event action object to GetAction interface")
 				}
 				handled, obj, err := opts.Getter.HandleGetAction(getAction)
 
@@ -139,7 +140,7 @@ func NewDryRunClientWithOpts(opts DryRunClientOptions) clientset.Interface {
 				listAction, ok := action.(core.ListAction)
 				if !ok {
 					// something's wrong, we can't handle this event
-					return true, nil, fmt.Errorf("can't cast list reactor event action object to ListAction interface")
+					return true, nil, errors.New("can't cast list reactor event action object to ListAction interface")
 				}
 				handled, objs, err := opts.Getter.HandleListAction(listAction)
 

cmd/kubeadm/app/util/apiclient/idempotency.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 
+	"github.com/pkg/errors"
 	apps "k8s.io/api/apps/v1"
 	"k8s.io/api/core/v1"
 	rbac "k8s.io/api/rbac/v1"
@@ -40,11 +41,11 @@ import (
 func CreateOrUpdateConfigMap(client clientset.Interface, cm *v1.ConfigMap) error {
 	if _, err := client.CoreV1().ConfigMaps(cm.ObjectMeta.Namespace).Create(cm); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create configmap: %v", err)
+			return errors.Wrap(err, "unable to create configmap")
 		}
 
 		if _, err := client.CoreV1().ConfigMaps(cm.ObjectMeta.Namespace).Update(cm); err != nil {
-			return fmt.Errorf("unable to update configmap: %v", err)
+			return errors.Wrap(err, "unable to update configmap")
 		}
 	}
 	return nil
@@ -58,7 +59,7 @@ func CreateOrRetainConfigMap(client clientset.Interface, cm *v1.ConfigMap, confi
 		}
 		if _, err := client.CoreV1().ConfigMaps(cm.ObjectMeta.Namespace).Create(cm); err != nil {
 			if !apierrors.IsAlreadyExists(err) {
-				return fmt.Errorf("unable to create configmap: %v", err)
+				return errors.Wrap(err, "unable to create configmap")
 			}
 		}
 	}
@@ -69,11 +70,11 @@ func CreateOrRetainConfigMap(client clientset.Interface, cm *v1.ConfigMap, confi
 func CreateOrUpdateSecret(client clientset.Interface, secret *v1.Secret) error {
 	if _, err := client.CoreV1().Secrets(secret.ObjectMeta.Namespace).Create(secret); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create secret: %v", err)
+			return errors.Wrap(err, "unable to create secret")
 		}
 
 		if _, err := client.CoreV1().Secrets(secret.ObjectMeta.Namespace).Update(secret); err != nil {
-			return fmt.Errorf("unable to update secret: %v", err)
+			return errors.Wrap(err, "unable to update secret")
 		}
 	}
 	return nil
@@ -85,7 +86,7 @@ func CreateOrUpdateServiceAccount(client clientset.Interface, sa *v1.ServiceAcco
 		// Note: We don't run .Update here afterwards as that's probably not required
 		// Only thing that could be updated is annotations/labels in .metadata, but we don't use that currently
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create serviceaccount: %v", err)
+			return errors.Wrap(err, "unable to create serviceaccount")
 		}
 	}
 	return nil
@@ -95,11 +96,11 @@ func CreateOrUpdateServiceAccount(client clientset.Interface, sa *v1.ServiceAcco
 func CreateOrUpdateDeployment(client clientset.Interface, deploy *apps.Deployment) error {
 	if _, err := client.AppsV1().Deployments(deploy.ObjectMeta.Namespace).Create(deploy); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create deployment: %v", err)
+			return errors.Wrap(err, "unable to create deployment")
 		}
 
 		if _, err := client.AppsV1().Deployments(deploy.ObjectMeta.Namespace).Update(deploy); err != nil {
-			return fmt.Errorf("unable to update deployment: %v", err)
+			return errors.Wrap(err, "unable to update deployment")
 		}
 	}
 	return nil
@@ -109,11 +110,11 @@ func CreateOrUpdateDeployment(client clientset.Interface, deploy *apps.Deploymen
 func CreateOrUpdateDaemonSet(client clientset.Interface, ds *apps.DaemonSet) error {
 	if _, err := client.AppsV1().DaemonSets(ds.ObjectMeta.Namespace).Create(ds); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create daemonset: %v", err)
+			return errors.Wrap(err, "unable to create daemonset")
 		}
 
 		if _, err := client.AppsV1().DaemonSets(ds.ObjectMeta.Namespace).Update(ds); err != nil {
-			return fmt.Errorf("unable to update daemonset: %v", err)
+			return errors.Wrap(err, "unable to update daemonset")
 		}
 	}
 	return nil
@@ -141,11 +142,11 @@ func DeleteDeploymentForeground(client clientset.Interface, namespace, name stri
 func CreateOrUpdateRole(client clientset.Interface, role *rbac.Role) error {
 	if _, err := client.RbacV1().Roles(role.ObjectMeta.Namespace).Create(role); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create RBAC role: %v", err)
+			return errors.Wrap(err, "unable to create RBAC role")
 		}
 
 		if _, err := client.RbacV1().Roles(role.ObjectMeta.Namespace).Update(role); err != nil {
-			return fmt.Errorf("unable to update RBAC role: %v", err)
+			return errors.Wrap(err, "unable to update RBAC role")
 		}
 	}
 	return nil
@@ -155,11 +156,11 @@ func CreateOrUpdateRole(client clientset.Interface, role *rbac.Role) error {
 func CreateOrUpdateRoleBinding(client clientset.Interface, roleBinding *rbac.RoleBinding) error {
 	if _, err := client.RbacV1().RoleBindings(roleBinding.ObjectMeta.Namespace).Create(roleBinding); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create RBAC rolebinding: %v", err)
+			return errors.Wrap(err, "unable to create RBAC rolebinding")
 		}
 
 		if _, err := client.RbacV1().RoleBindings(roleBinding.ObjectMeta.Namespace).Update(roleBinding); err != nil {
-			return fmt.Errorf("unable to update RBAC rolebinding: %v", err)
+			return errors.Wrap(err, "unable to update RBAC rolebinding")
 		}
 	}
 	return nil
@@ -169,11 +170,11 @@ func CreateOrUpdateRoleBinding(client clientset.Interface, roleBinding *rbac.Rol
 func CreateOrUpdateClusterRole(client clientset.Interface, clusterRole *rbac.ClusterRole) error {
 	if _, err := client.RbacV1().ClusterRoles().Create(clusterRole); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create RBAC clusterrole: %v", err)
+			return errors.Wrap(err, "unable to create RBAC clusterrole")
 		}
 
 		if _, err := client.RbacV1().ClusterRoles().Update(clusterRole); err != nil {
-			return fmt.Errorf("unable to update RBAC clusterrole: %v", err)
+			return errors.Wrap(err, "unable to update RBAC clusterrole")
 		}
 	}
 	return nil
@@ -183,11 +184,11 @@ func CreateOrUpdateClusterRole(client clientset.Interface, clusterRole *rbac.Clu
 func CreateOrUpdateClusterRoleBinding(client clientset.Interface, clusterRoleBinding *rbac.ClusterRoleBinding) error {
 	if _, err := client.RbacV1().ClusterRoleBindings().Create(clusterRoleBinding); err != nil {
 		if !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("unable to create RBAC clusterrolebinding: %v", err)
+			return errors.Wrap(err, "unable to create RBAC clusterrolebinding")
 		}
 
 		if _, err := client.RbacV1().ClusterRoleBindings().Update(clusterRoleBinding); err != nil {
-			return fmt.Errorf("unable to update RBAC clusterrolebinding: %v", err)
+			return errors.Wrap(err, "unable to update RBAC clusterrolebinding")
 		}
 	}
 	return nil

cmd/kubeadm/app/util/apiclient/wait.go

@@ -22,6 +22,7 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/pkg/errors"
 	"k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -143,7 +144,7 @@ func (w *KubeWaiter) WaitForHealthyKubelet(initalTimeout time.Duration, healthzE
 		if resp.StatusCode != http.StatusOK {
 			fmt.Printf("[kubelet-check] It seems like the kubelet isn't running or healthy.")
 			fmt.Printf("[kubelet-check] The HTTP call equal to 'curl -sSL %s' returned HTTP code %d\n", healthzEndpoint, resp.StatusCode)
-			return fmt.Errorf("the kubelet healthz endpoint is unhealthy")
+			return errors.New("the kubelet healthz endpoint is unhealthy")
 		}
 		return nil
 	}, 5) // a failureThreshold of five means waiting for a total of 155 seconds

cmd/kubeadm/app/util/arguments.go

@@ -20,6 +20,8 @@ import (
 	"fmt"
 	"sort"
 	"strings"
+
+	"github.com/pkg/errors"
 )
 
 // BuildArgumentListFromMap takes two string-string maps, one with the base arguments and one
@@ -89,10 +91,10 @@ func ReplaceArgument(command []string, argMutateFunc func(map[string]string) map
 // parseArgument parses the argument "--foo=bar" to "foo" and "bar"
 func parseArgument(arg string) (string, string, error) {
 	if !strings.HasPrefix(arg, "--") {
-		return "", "", fmt.Errorf("the argument should start with '--'")
+		return "", "", errors.New("the argument should start with '--'")
 	}
 	if !strings.Contains(arg, "=") {
-		return "", "", fmt.Errorf("the argument should have a '=' between the flag and the value")
+		return "", "", errors.New("the argument should have a '=' between the flag and the value")
 	}
 	// Remove the starting --
 	arg = strings.TrimPrefix(arg, "--")
@@ -101,10 +103,10 @@ func parseArgument(arg string) (string, string, error) {
 
 	// Make sure both a key and value is present
 	if len(keyvalSlice) != 2 {
-		return "", "", fmt.Errorf("the argument must have both a key and a value")
+		return "", "", errors.New("the argument must have both a key and a value")
 	}
 	if len(keyvalSlice[0]) == 0 {
-		return "", "", fmt.Errorf("the argument must have a key")
+		return "", "", errors.New("the argument must have a key")
 	}
 
 	return keyvalSlice[0], keyvalSlice[1], nil

cmd/kubeadm/app/util/cgroupdriver.go

@@ -20,6 +20,8 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/pkg/errors"
+
 	utilsexec "k8s.io/utils/exec"
 )
 
@@ -51,7 +53,7 @@ func validateCgroupDriver(driver string) error {
 func callDockerInfo(execer utilsexec.Interface) (string, error) {
 	out, err := execer.Command("docker", "info").Output()
 	if err != nil {
-		return "", fmt.Errorf("cannot execute 'docker info': %v", err)
+		return "", errors.Wrap(err, "cannot execute 'docker info'")
 	}
 	return string(out), nil
 }
@@ -71,5 +73,5 @@ func getCgroupDriverFromDockerInfo(info string) (string, error) {
 		}
 		return driver, nil
 	}
-	return "", fmt.Errorf("cgroup driver is not defined in 'docker info'")
+	return "", errors.New("cgroup driver is not defined in 'docker info'")
 }

cmd/kubeadm/app/util/etcd/BUILD

@@ -11,6 +11,7 @@ go_library(
         "//cmd/kubeadm/app/util/staticpod:go_default_library",
         "//vendor/github.com/coreos/etcd/clientv3:go_default_library",
         "//vendor/github.com/coreos/etcd/pkg/transport:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/util/etcd/etcd.go

@@ -26,6 +26,7 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 	"github.com/coreos/etcd/pkg/transport"
+	"github.com/pkg/errors"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/staticpod"
@@ -58,7 +59,7 @@ func PodManifestsHaveTLS(ManifestDir string) (bool, error) {
 	etcdPodPath := constants.GetStaticPodFilepath(constants.Etcd, ManifestDir)
 	etcdPod, err := staticpod.ReadStaticPodFromDisk(etcdPodPath)
 	if err != nil {
-		return false, fmt.Errorf("failed to check if etcd pod implements TLS: %v", err)
+		return false, errors.Wrap(err, "failed to check if etcd pod implements TLS")
 	}
 
 	tlsFlags := []string{
@@ -140,7 +141,7 @@ func (c Client) GetVersion() (string, error) {
 		clusterVersion = v
 	}
 	if clusterVersion == "" {
-		return "", fmt.Errorf("could not determine cluster etcd version")
+		return "", errors.New("could not determine cluster etcd version")
 	}
 	return clusterVersion, nil
 }
@@ -215,7 +216,7 @@ func (c Client) WaitForClusterAvailable(delay time.Duration, retries int, retryI
 		}
 		return resp, nil
 	}
-	return false, fmt.Errorf("timeout waiting for etcd cluster to be available")
+	return false, errors.New("timeout waiting for etcd cluster to be available")
 }
 
 // CheckConfigurationIsHA returns true if the given InitConfiguration etcd block appears to be an HA configuration.

cmd/kubeadm/app/util/kubeconfig/BUILD

@@ -20,6 +20,7 @@ go_library(
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//staging/src/k8s.io/client-go/tools/clientcmd:go_default_library",
         "//staging/src/k8s.io/client-go/tools/clientcmd/api:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/util/kubeconfig/kubeconfig.go

@@ -22,6 +22,8 @@ import (
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/clientcmd"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+
+	"github.com/pkg/errors"
 )
 
 // CreateBasic creates a basic, general KubeConfig object that then can be extended
@@ -70,7 +72,7 @@ func CreateWithToken(serverURL, clusterName, userName string, caCert []byte, tok
 func ClientSetFromFile(path string) (*clientset.Clientset, error) {
 	config, err := clientcmd.LoadFromFile(path)
 	if err != nil {
-		return nil, fmt.Errorf("failed to load admin kubeconfig [%v]", err)
+		return nil, errors.Wrap(err, "failed to load admin kubeconfig")
 	}
 	return ToClientSet(config)
 }
@@ -79,12 +81,12 @@ func ClientSetFromFile(path string) (*clientset.Clientset, error) {
 func ToClientSet(config *clientcmdapi.Config) (*clientset.Clientset, error) {
 	clientConfig, err := clientcmd.NewDefaultClientConfig(*config, &clientcmd.ConfigOverrides{}).ClientConfig()
 	if err != nil {
-		return nil, fmt.Errorf("failed to create API client configuration from kubeconfig: %v", err)
+		return nil, errors.Wrap(err, "failed to create API client configuration from kubeconfig")
 	}
 
 	client, err := clientset.NewForConfig(clientConfig)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create API client: %v", err)
+		return nil, errors.Wrap(err, "failed to create API client")
 	}
 	return client, nil
 }

cmd/kubeadm/app/util/system/BUILD

@@ -28,6 +28,7 @@ go_library(
         "//vendor/github.com/docker/docker/api/types:go_default_library",
         "//vendor/github.com/docker/docker/client:go_default_library",
         "//vendor/github.com/golang/glog:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
     ],
 )
 

cmd/kubeadm/app/util/system/cgroup_validator.go

@@ -21,6 +21,8 @@ import (
 	"fmt"
 	"os"
 	"strings"
+
+	"github.com/pkg/errors"
 )
 
 var _ Validator = &CgroupsValidator{}
@@ -40,7 +42,7 @@ const (
 func (c *CgroupsValidator) Validate(spec SysSpec) (error, error) {
 	subsystems, err := c.getCgroupSubsystems()
 	if err != nil {
-		return nil, fmt.Errorf("failed to get cgroup subsystems: %v", err)
+		return nil, errors.Wrap(err, "failed to get cgroup subsystems")
 	}
 	return nil, c.validateCgroupSubsystems(spec.Cgroups, subsystems)
 }

cmd/kubeadm/app/util/system/docker_validator.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/client"
+	"github.com/pkg/errors"
 )
 
 var _ Validator = &DockerValidator{}
@@ -51,11 +52,11 @@ func (d *DockerValidator) Validate(spec SysSpec) (error, error) {
 
 	c, err := client.NewClient(dockerEndpoint, "", nil, nil)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create docker client: %v", err)
+		return nil, errors.Wrap(err, "failed to create docker client")
 	}
 	info, err := c.Info(context.Background())
 	if err != nil {
-		return nil, fmt.Errorf("failed to get docker info: %v", err)
+		return nil, errors.Wrap(err, "failed to get docker info")
 	}
 	return d.validateDockerInfo(spec.RuntimeSpec.DockerSpec, info)
 }

cmd/kubeadm/app/util/system/os_validator.go

@@ -20,6 +20,8 @@ import (
 	"fmt"
 	"os/exec"
 	"strings"
+
+	"github.com/pkg/errors"
 )
 
 var _ Validator = &OSValidator{}
@@ -35,7 +37,7 @@ func (o *OSValidator) Name() string {
 func (o *OSValidator) Validate(spec SysSpec) (error, error) {
 	os, err := exec.Command("uname").CombinedOutput()
 	if err != nil {
-		return nil, fmt.Errorf("failed to get os name: %v", err)
+		return nil, errors.Wrap(err, "failed to get os name")
 	}
 	return nil, o.validateOS(strings.TrimSpace(string(os)), spec.OS)
 }

cmd/kubeadm/app/util/template.go

@@ -18,8 +18,9 @@ package util
 
 import (
 	"bytes"
-	"fmt"
 	"text/template"
+
+	"github.com/pkg/errors"
 )
 
 // ParseTemplate validates and parses passed as argument template
@@ -27,11 +28,11 @@ func ParseTemplate(strtmpl string, obj interface{}) ([]byte, error) {
 	var buf bytes.Buffer
 	tmpl, err := template.New("template").Parse(strtmpl)
 	if err != nil {
-		return nil, fmt.Errorf("error when parsing template: %v", err)
+		return nil, errors.Wrap(err, "error when parsing template")
 	}
 	err = tmpl.Execute(&buf, obj)
 	if err != nil {
-		return nil, fmt.Errorf("error when executing template: %v", err)
+		return nil, errors.Wrap(err, "error when executing template")
 	}
 	return buf.Bytes(), nil
 }