rpk: Unknown flag error when command is misspelled

[travisdowns]

Version & Environment

Redpanda version: 21.11.10

What went wrong?

Consider the following command and error output:

rpk topic add-paritions t0 --num 1000
Error: unknown flag: --num

What should have happened instead?

The error should be "Unknown command add-paritions" (it is misspelled) rather than a complaint about the flag, which is correct for the (correctly spelled) command.

How to reproduce the issue?

1. As above.

JIRA Link: CORE-890

[daisukebe]

It seems to be emitted by cobra, https://github.com/spf13/cobra/blob/v1.1.3/command.go#L942-L944, and apparently the latest cobra 1.4.0 works in the same way.

Within rpk, we can interrupt with a way like below, but I'm unsure whether this is fine.

src/go/rpk/pkg/cli/cmd/topic.go

	if _, _, err := command.Find(os.Args[2:]); err != nil {
		log.Info(err)
		os.Exit(1)
	}

	return command
}

Example output with above:

$ rpk topic add-paritions bar --num 10
unknown command "add-paritions" for "topic"

Did you mean this?
	add-partitions

Related discussion in the cobra community, spf13/cobra#706

[r-vasquez]

Thanks @daisukebe for the context, indeed the problem does not go away with cobra 1.4.0. This is an issue in cobra side:

spf13/cobra#1409

If this is something that we need, we may go with the above approach and interrupt in each command, or another thing that we could do is to add additional info in the flag errors, e.g:

Currently:

$ rpk topic add-paritions t0 --num 1000

Error: unknown flag: --num

<Usage for rpk topic>

We can do something like:

$ rpk topic add-paritions t0 --num 1000

Error: unknown flag: --num
See 'rpk topic --help'

<Usage for rpk topic>

However I think is redundant since we already print the usage, what do you think?

CC: @twmb

[twmb]

I agree this is more in the guts of cobra. Perhaps long term we can evaluate switching away from cobra (which has a bunch of other challenging nuts&bolts we currently work around / with). For now, I think we can wait for the two cobra issues linked above for now and leave this open.