From 90faa6b5fd1ef390f7e2362479337e69015914a9 Mon Sep 17 00:00:00 2001
From: Ciprian Hacman <ciprian@hakman.dev>
Date: Sun, 15 May 2022 08:46:33 +0300
Subject: [PATCH] Allow overriding the kubernetes version when upgrading the
 cluster

---
 cmd/kops/upgrade_cluster.go      | 17 +++++++++++++++--
 docs/cli/kops_upgrade_cluster.md |  7 ++++---
 docs/releases/1.24-NOTES.md      |  2 ++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/cmd/kops/upgrade_cluster.go b/cmd/kops/upgrade_cluster.go
index 1445b10bcf..f964c33532 100644
--- a/cmd/kops/upgrade_cluster.go
+++ b/cmd/kops/upgrade_cluster.go
@@ -58,6 +58,8 @@ type UpgradeClusterOptions struct {
 	ClusterName string
 	Yes         bool
 	Channel     string
+	// KubernetesVersion is the k8s version to use for upgrade.
+	KubernetesVersion string
 }
 
 func NewCmdUpgradeCluster(f *util.Factory, out io.Writer) *cobra.Command {
@@ -80,6 +82,8 @@ func NewCmdUpgradeCluster(f *util.Factory, out io.Writer) *cobra.Command {
 	cmd.Flags().BoolVarP(&options.Yes, "yes", "y", false, "Apply update")
 	cmd.Flags().StringVar(&options.Channel, "channel", "", "Channel to use for upgrade")
 	cmd.RegisterFlagCompletionFunc("channel", completeChannel)
+	cmd.Flags().StringVar(&options.KubernetesVersion, "kubernetes-version", "", "Kubernetes version to use for upgrade")
+	cmd.RegisterFlagCompletionFunc("kubernetes-version", completeKubernetesVersion)
 
 	return cmd
 }
@@ -149,12 +153,21 @@ func RunUpgradeCluster(ctx context.Context, f *util.Factory, out io.Writer, opti
 		}
 	}
 
-	proposedKubernetesVersion := kopsapi.RecommendedKubernetesVersion(channel, kops.Version)
+	var proposedKubernetesVersion *semver.Version
+	if options.KubernetesVersion != "" {
+		proposedKubernetesVersion, err = kopsutil.ParseKubernetesVersion(options.KubernetesVersion)
+		if err != nil {
+			klog.Warningf("error parsing KubernetesVersion %q", cluster.Spec.KubernetesVersion)
+		}
+	}
+	if proposedKubernetesVersion == nil {
+		proposedKubernetesVersion = kopsapi.RecommendedKubernetesVersion(channel, kops.Version)
+	}
 
 	// We won't propose a downgrade
 	// TODO: What if a kubernetes version is bad?
 	if currentKubernetesVersion != nil && proposedKubernetesVersion != nil && currentKubernetesVersion.GT(*proposedKubernetesVersion) {
-		klog.Warningf("cluster version %q is greater than recommended version %q", *currentKubernetesVersion, *proposedKubernetesVersion)
+		klog.Warningf("cluster version %q is greater than the desired version %q", *currentKubernetesVersion, *proposedKubernetesVersion)
 		proposedKubernetesVersion = currentKubernetesVersion
 	}
 
diff --git a/docs/cli/kops_upgrade_cluster.md b/docs/cli/kops_upgrade_cluster.md
index 973fb48b58..8fe4fc7ef6 100644
--- a/docs/cli/kops_upgrade_cluster.md
+++ b/docs/cli/kops_upgrade_cluster.md
@@ -25,9 +25,10 @@ kops upgrade cluster [CLUSTER] [flags]
 ### Options
 
 ```
-      --channel string   Channel to use for upgrade
-  -h, --help             help for cluster
-  -y, --yes              Apply update
+      --channel string              Channel to use for upgrade
+  -h, --help                        help for cluster
+      --kubernetes-version string   Kubernetes version to use for upgrade
+  -y, --yes                         Apply update
 ```
 
 ### Options inherited from parent commands
diff --git a/docs/releases/1.24-NOTES.md b/docs/releases/1.24-NOTES.md
index 9cb5369c00..03b4e1b213 100644
--- a/docs/releases/1.24-NOTES.md
+++ b/docs/releases/1.24-NOTES.md
@@ -25,6 +25,8 @@ kOps will directly manage the Karpenter Provisioner resources. Read more about h
 
 * Adds support for Rocky Linux 8
 
+* Adds support for overriding the Kubernetes version when upgrading a cluster by using the `--kubernetes-version` flag.
+
 * The minimum version for the Terraform AWS Provider has been bumped to 4.0.0 to address the deprecation of the aws_s3_bucket_object resource and its replacement with the aws_s3_object resource. Such resources will be destroyed and recreated without downtime when applying the changes. 
 
 * ARM64 support for nvidia device driver. Nvidia nodes on ARM64 requires Ubuntu 22.04 AMIs.