kubernetes/cmd/kubeadm/app/cmd/upgrade/common.go

// enforceRequirements verifies that it's okay to upgrade and then returns the variables needed for the rest of the procedure
func enforceRequirements(flagSet *pflag.FlagSet, flags *applyPlanFlags, args []string, dryRun bool, upgradeApply bool, printer output.Printer) (clientset.Interface, upgrade.VersionGetter, *kubeadmapi.InitConfiguration, *kubeadmapi.UpgradeConfiguration, error) { … }

// printConfiguration prints the external version of the API to yaml
func printConfiguration(clustercfg *kubeadmapi.ClusterConfiguration, w io.Writer, printer output.Printer) { … }

// runPreflightChecks runs the root preflight check
func runPreflightChecks(client clientset.Interface, ignorePreflightErrors sets.Set[string], printer output.Printer) error { … }

// getClient gets a real or fake client depending on whether the user is dry-running or not
func getClient(file string, dryRun bool) (clientset.Interface, error) { … }