kubeadm upgrade plan: Use internal types of the output API

`kubeadm upgrade plan` is using the external (currently `v1alpha1`) types of
the kubeadm output API to collect upgrade plans. This is counter intuitive
since code structure gets bound to the whatever version the output API is at.
In addition to that, the versioned API is used only in the very last stages of
a machine readable output (which is currently not implemented).

Hence, to increase flexibility and keep up with the standard Kubernetes
ecosystem practice, `kubeadm upgrade plan` is migrated to use the internal
types of the output API.

Signed-off-by: Rostislav M. Georgiev <[email protected]>

Author: rosti

cmd/kubeadm/app/cmd/upgrade/BUILD

@@ -15,7 +15,7 @@ go_library(
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/apis/kubeadm/validation:go_default_library",
-        "//cmd/kubeadm/app/apis/output/v1alpha1:go_default_library",
+        "//cmd/kubeadm/app/apis/output:go_default_library",
         "//cmd/kubeadm/app/cmd/options:go_default_library",
         "//cmd/kubeadm/app/cmd/phases/upgrade/node:go_default_library",
         "//cmd/kubeadm/app/cmd/phases/workflow:go_default_library",

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

@@ -26,10 +26,11 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
+
 	"k8s.io/apimachinery/pkg/util/version"
 	"k8s.io/klog/v2"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
-	outputapiv1alpha1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/output/v1alpha1"
+	outputapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/output"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/phases/upgrade"
 )
@@ -96,9 +97,9 @@ func runPlan(flags *planFlags, args []string) error {
 	return nil
 }
 
-// newComponentUpgradePlan helper creates outputapiv1alpha1.ComponentUpgradePlan object
-func newComponentUpgradePlan(name, currentVersion, newVersion string) outputapiv1alpha1.ComponentUpgradePlan {
-	return outputapiv1alpha1.ComponentUpgradePlan{
+// newComponentUpgradePlan helper creates outputapi.ComponentUpgradePlan object
+func newComponentUpgradePlan(name, currentVersion, newVersion string) outputapi.ComponentUpgradePlan {
+	return outputapi.ComponentUpgradePlan{
 		Name:           name,
 		CurrentVersion: currentVersion,
 		NewVersion:     newVersion,
@@ -107,7 +108,7 @@ func newComponentUpgradePlan(name, currentVersion, newVersion string) outputapiv
 
 // TODO There is currently no way to cleanly output upgrades that involve adding, removing, or changing components
 // https://github.com/kubernetes/kubeadm/issues/810 was created to track addressing this.
-func appendDNSComponent(components []outputapiv1alpha1.ComponentUpgradePlan, up *upgrade.Upgrade, DNSType kubeadmapi.DNSAddOnType, name string) []outputapiv1alpha1.ComponentUpgradePlan {
+func appendDNSComponent(components []outputapi.ComponentUpgradePlan, up *upgrade.Upgrade, DNSType kubeadmapi.DNSAddOnType, name string) []outputapi.ComponentUpgradePlan {
 	beforeVersion, afterVersion := "", ""
 	if up.Before.DNSType == DNSType {
 		beforeVersion = up.Before.DNSVersion
@@ -123,7 +124,7 @@ func appendDNSComponent(components []outputapiv1alpha1.ComponentUpgradePlan, up
 }
 
 // genUpgradePlan generates output-friendly upgrade plan out of upgrade.Upgrade structure
-func genUpgradePlan(up *upgrade.Upgrade, isExternalEtcd bool) (*outputapiv1alpha1.UpgradePlan, string, error) {
+func genUpgradePlan(up *upgrade.Upgrade, isExternalEtcd bool) (*outputapi.UpgradePlan, string, error) {
 	newK8sVersion, err := version.ParseSemantic(up.After.KubeVersion)
 	if err != nil {
 		return nil, "", errors.Wrapf(err, "Unable to parse normalized version %q as a semantic version", up.After.KubeVersion)
@@ -138,7 +139,7 @@ func genUpgradePlan(up *upgrade.Upgrade, isExternalEtcd bool) (*outputapiv1alpha
 		}
 	}
 
-	components := []outputapiv1alpha1.ComponentUpgradePlan{}
+	components := []outputapi.ComponentUpgradePlan{}
 
 	if up.CanUpgradeKubelets() {
 		// The map is of the form <old-version>:<node-count>. Here all the keys are put into a slice and sorted
@@ -161,11 +162,11 @@ func genUpgradePlan(up *upgrade.Upgrade, isExternalEtcd bool) (*outputapiv1alpha
 		components = append(components, newComponentUpgradePlan(constants.Etcd, up.Before.EtcdVersion, up.After.EtcdVersion))
 	}
 
-	return &outputapiv1alpha1.UpgradePlan{Components: components}, unstableVersionFlag, nil
+	return &outputapi.UpgradePlan{Components: components}, unstableVersionFlag, nil
 }
 
 // printUpgradePlan prints a UX-friendly overview of what versions are available to upgrade to
-func printUpgradePlan(up *upgrade.Upgrade, plan *outputapiv1alpha1.UpgradePlan, unstableVersionFlag string, isExternalEtcd bool, w io.Writer) {
+func printUpgradePlan(up *upgrade.Upgrade, plan *outputapi.UpgradePlan, unstableVersionFlag string, isExternalEtcd bool, w io.Writer) {
 	// The tab writer writes to the "real" writer w
 	tabw := tabwriter.NewWriter(w, 10, 4, 3, ' ', 0)