Cobra command Kubectl Create does not return error to be handled

[oglok]

What happened:

I'm writing a function to basically do kubectl create -k /path. However, If the manifests there have already been created, I don't want my program to exit, but just ignore it.

This is a quick snippet:

func createKustomization(kustomization string, kubeconfig string) error {
	klog.Infof("Using create policy with kustomization at %s", kustomization)

	cmds := &cobra.Command{
		Use:   "kubectl",
		Short: "kubectl",
	}
	persistFlags := cmds.PersistentFlags()
	persistFlags.SetNormalizeFunc(cliflag.WarnWordSepNormalizeFunc)
	persistFlags.SetNormalizeFunc(cliflag.WordSepNormalizeFunc)

	kubeConfigFlags := genericclioptions.NewConfigFlags(true).WithDeprecatedPasswordFlag()
	kubeConfigFlags.KubeConfig = &kubeconfig
	kubeConfigFlags.AddFlags(persistFlags)

	matchVersionKubeConfigFlags := cmdutil.NewMatchVersionFlags(kubeConfigFlags)
	matchVersionKubeConfigFlags.AddFlags(persistFlags)

	f := cmdutil.NewFactory(matchVersionKubeConfigFlags)
	ioStreams := genericclioptions.IOStreams{In: os.Stdin, Out: os.Stdout, ErrOut: os.Stderr}
	createCmd := create.NewCmdCreate(f, ioStreams)
	createCmd.SetArgs([]string{"-k", kustomization})
	createCmd.SetOut(ioStreams.Out)
	createCmd.SetErr(ioStreams.ErrOut)
	createCmd.SetIn(ioStreams.In)

	klog.Infof("Executing create command")
	createCmd.SilenceUsage = true
	err := createCmd.Execute()
	if err != nil {
		klog.Infof("Creating kustomization failed: %s", err)
		return nil
	}

	klog.Infof("Kustomization applied successfully")
	return nil

}

createCmd.Execute() just throws an error, but It never gets into klog.Infof("Creating kustomization failed: %s", err)

Am I doing something wrong?

What you expected to happen:

To return an error so I can handle it.

Anything else we need to know?:

Environment:
Library: k8s.io/kubectl v0.30.2

• Kubernetes client and server versions (use kubectl version):
• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):

[brianpursley]

The problem, as you found out, is that inside Cobra's Run() command, we use cmdutil.CheckErr() which by default will os.Exit() when an error occurs, instead of returning it.

Ideally, instead of calling cmd.Execute() you should be able to call o.RunCreate() on CreateOptions without needing to instantiate a Cobra command (or iostreams) at all.

Unfortunately, the create command is written in a way that requires a cobra command, even if you want to call o.RunCreate() directly. It should be refactored to be like other commands, which do not require this.

---

But, as a workaround, you might be able to make it work by calling RunCreate() and pass it a dummy cobra command, since I don't think you need any of the code paths that use that argument. Something like this...

func createKustomization(kustomization string, kubeconfig string) error {
	klog.Infof("Using create policy with kustomization at %s", kustomization)

	kubeConfigFlags := genericclioptions.NewConfigFlags(true).WithDeprecatedPasswordFlag()
	kubeConfigFlags.KubeConfig = &kubeconfig

	matchVersionKubeConfigFlags := cmdutil.NewMatchVersionFlags(kubeConfigFlags)

	f := cmdutil.NewFactory(matchVersionKubeConfigFlags)
	ioStreams := genericiooptions.IOStreams{In: os.Stdin, Out: os.Stdout, ErrOut: os.Stderr}

	o := create.NewCreateOptions(ioStreams)
	o.FilenameOptions.Kustomize = kustomization
	dummyCmd := &cobra.Command{}
	err := o.RunCreate(f, dummyCmd)
	if err != nil {
		klog.Errorf("Creating kustomization failed: %s", err)
		return err
	}

	klog.Infof("Kustomization applied successfully")
	return nil
}

Alternatively, you could forget about trying to leverage create altogether and just copy the code you need out of the RunCreate() func. Depending on how specific your needs are, this might make sense as another option to consider.

Also, would apply work for you, instead of create? That might end up being easier to work with.

[ardaguclu]

/kind support

[oglok]

Thank you very much @brianpursley ! that makes sense!
your suggestion worked perfectly, I just needed to add one line:
dummyCmd.Flags().Bool("save-config", false, "If true, save the configuration after applying")

Should we open a GH issue for the refactor?

[brianpursley]

Cool, I'm glad you were able to work around it. The point raised in your issue is definitely valid though.

Should we open a GH issue for the refactor?

There is a somewhat related umbrella issue (#1046), but that is more about separating the options from the flags, which is a slightly different problem than this. It looks like there were a couple of previous attempts to refactor this command as part of that issue, but they were not able to be merged.

@ardaguclu do you have thoughts on whether this should be a separate issue or fall under the umbrella?

[ardaguclu]

I think, we can manage this specific change in this issue. The other one requires more dramatic changes.

[ardaguclu]

/remove-kind support
/triage accepted
/priority backlog