Which command is used to upgrade a Tanzu Kubernetes Grid Cluster (TKG) to a different kubernetes version?

The correct command to upgrade a Tanzu Kubernetes Grid (TKG) workload cluster is tkg upgrade cluster. This command initiates the upgrade process for the specified cluster. To target a specific Kubernetes release, the --kubernetes-version flag is used, followed by the desired version string (e.g., v1.23.8---vmware.1-tkg.1). The command first upgrades the control plane nodes and then proceeds to upgrade the worker nodes, ensuring a controlled and sequential update of the cluster's Kubernetes version.

A. tkg cluster upgrade is an incorrect command structure. The correct verb is upgrade, and the object is cluster. Also, --k8s-version is not a valid flag.
C. tkg cluster upgrade uses an incorrect command structure. The command for upgrading a cluster is tkg upgrade cluster.
D. The --version flag is generally used to check the version of the tkg CLI tool itself, not to specify the target Kubernetes version for a cluster upgrade.

1. VMware Tanzu Kubernetes Grid 1.6 Documentation

"Upgrade TKG Clusters". This official documentation explicitly states the command syntax: tkg upgrade cluster CLUSTER-NAME [FLAGS]. It lists the --kubernetes-version flag with the description: "The Kubernetes version to upgrade to."

Section: "Upgrade TKG Clusters"

2. VMware Tanzu CLI v0.90.1 Command Reference

"tkg upgrade cluster". This reference guide details the command usage and flags. It confirms the syntax tkg upgrade cluster [cluster-name] and lists --kubernetes-version as the flag to specify the "Kubernetes version to upgrade to."

Section: "tkg upgrade cluster"

3. VMware Tanzu Kubernetes Grid 2.1 Documentation

"Upgrade Workload Clusters". The documentation for newer versions also confirms the command structure. It provides the example: tkg cluster upgrade CLUSTER-NAME --kubernetes-version VERSION. Note: In TKG 2.x

the command alias tkg cluster upgrade was introduced

but tkg upgrade cluster remains the primary and backward-compatible command. However

the flag remains --kubernetes-version

making options A and D incorrect regardless. The question context aligns with the more established tkg upgrade cluster syntax.

Section: "Upgrade a Workload Cluster"