Optimize slice initialization in kubeadm

Signed-off-by: bo.jiang <bo.jiang@daocloud.io>

cmd/kubeadm/app/cmd/init.go

@@ -597,7 +597,7 @@ func (d *initData) WaitControlPlaneClient() (clientset.Interface, error) {
 
 // Tokens returns an array of token strings.
 func (d *initData) Tokens() []string {
-	tokens := []string{}
+	tokens := make([]string, 0, len(d.cfg.BootstrapTokens))
 	for _, bt := range d.cfg.BootstrapTokens {
 		tokens = append(tokens, bt.Token.String())
 	}

cmd/kubeadm/app/cmd/phases/init/kubeletfinalize.go

@@ -35,7 +35,7 @@ import (
 
 var (
 	kubeletFinalizePhaseExample = cmdutil.Examples(`
-		# Updates settings relevant to the kubelet after TLS bootstrap"
+		# Updates settings relevant to the kubelet after TLS bootstrap
 		kubeadm init phase kubelet-finalize all --config
 		`)
 )

cmd/kubeadm/app/cmd/upgrade/plan.go

@@ -234,7 +234,7 @@ func genAvailableUpgrade(up *upgrade.Upgrade, etcdUpgrade bool) outputapiv1alpha
 
 // sortedSliceFromStringStringArrayMap returns a slice of the keys in the map sorted alphabetically
 func sortedSliceFromStringStringArrayMap(strMap map[string][]string) []string {
-	strSlice := []string{}
+	strSlice := make([]string, 0, len(strMap))
 	for k := range strMap {
 		strSlice = append(strSlice, k)
 	}