Backport of Add cli autocomplete into release/0.0.x

[hc-github-team-consul-ecosystem]

Backport

This PR is auto-generated from #1501 to be assessed for backporting due to the inclusion of the label backport/0.0.x.

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The below text is copied from the body of the original PR.

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Changes proposed in this PR:

• see description

How I've tested this PR:

• ran through auto-completions tabbing through commands
• unit tests written to make sure that number of flags matches the number of auto-completion suggestions

How I expect reviewers to test this PR:

• run consul-k8s, activate autocomplete, and try it out

Checklist:

• Tests added
• CHANGELOG entry added

  HashiCorp engineers only, community PRs should not add a changelog entry.
  Entries should use present tense (e.g. Add support for...)

Description

• Added tab autocompletion to the consul-k8s CLI. Commands are automatically supported, but flags require implementing the completion interface per command

example for consul-k8s install:

// AutocompleteFlags returns a mapping of supported flags and autocomplete
// options for this command. The map key for the Flags map should be the
// complete flag such as "-foo" or "--foo".
func (c *Command) AutocompleteFlags() complete.Flags {
	return complete.Flags{
		fmt.Sprintf("-%s", flagNamePreset):          complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameNamespace):       complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameDryRun):          complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameAutoApprove):     complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameConfigFile):      complete.PredictFiles("*"),
		fmt.Sprintf("-%s", flagNameSetStringValues): complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameSetValues):       complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameFileValues):      complete.PredictFiles("*"),
		fmt.Sprintf("-%s", flagNameTimeout):         complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameVerbose):         complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameWait):            complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameContext):         complete.PredictNothing,
		fmt.Sprintf("-%s", flagNameKubeconfig):      complete.PredictNothing,
	}
}

// AutocompleteArgs returns the argument predictor for this command.
// Since argument completion is not supported, this will return
// complete.PredictNothing.
func (c *Command) AutocompleteArgs() complete.Predictor {
	return complete.PredictNothing
}

• complete.PredictNothing instructs that no completion should be offered
• complete.PredictFiles("*") instructs that completion should suggest any file in the running directory

Usage

Enable autocompletion by running:

$ consul-k8s -autocomplete-install

You need to open a new console for this to take effect.

Disable autocompletion by running:

$ consul-k8s -autocomplete-install

You need to open a new console for this to take effect.

When you start typing a consul-k8s command, press the <tab> character to show a list of available completions. Type -<tab> to show available flag completions.

Example command complete

Example flag complete

Shell Support

Autocompletion is supported via the posener/complete library which is included in the mitchell/cli library. This library supports bash, zsh and fish.

Future Support

Right now we only support basic completions (commands, flags, or files) add more complex completions for example:

• parse flags and make pod suggestions i.e. consul-k8s proxy read -n consul <tab> will provide a list of pods in the consul namespace
• provide set value suggestions based on those in the helm values file

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Overview of commits

• 1edab03 - 9c69119 - dc1cc99 - 5b3bd5d - 7c593a4