Support autocompletion for kuberc aliases

[hendrikKahl]

What would you like to be added:

It would be great, if aliases in a kuberc file would trigger / work with regular kubectl autocompletion.

Why is this needed:

For generic aliases autocompletion would super useful. For example, an alias like the following would be even more useful, if autocompletion would work for both kind and resource names.

  - name: gs
    command: get
    flags:
    - name: sort-by
      default: '{..creationTimestamp}'

[ardaguclu]

Thank you for opening this issue and your interest on kuberc.

I'll mark this as triage accepted to investigate more. Just be aware that this doesn't mean that we'll add this feature soon (or ever).
/triage accepted
/assign

[hendrikKahl]

Thanks for taking a look :)

Just to share a bit more context - I tried it with a v1.33.0 kubectl in a zsh. I could not get autocompletion for the alias but for regular kubectl commands it works perfectly fine.

========= starting completion logic ==========
CURRENT: 3, words[*]: kubectl gs
Truncated words[*]: kubectl gs ,
lastParam: , lastChar:
Adding extra empty parameter
About to call: eval kubectl __complete gs  ""
[Debug] Cleared global flags for plugin completion
[Debug] [Error] unable to find a command for arguments: [gs]
completion output: :0
last line: :0
directive: 0
completions:
flagPrefix:
Calling _describe
_describe did not find completions.
Checking if we should do file completion.
Activating file completion

vs

========= starting completion logic ==========
CURRENT: 3, words[*]: kubectl get
Truncated words[*]: kubectl get ,
lastParam: , lastChar:
Adding extra empty parameter
About to call: eval kubectl __complete get  ""
completion output: componentstatuses
configmaps
endpoints
events
...

[ardaguclu]

@marckhouzam would you have any thoughts about how we can implement completions for the aliases that actually maps to the actual kubectl commands prior to command execution.

[marckhouzam]

I had to debug to see why it wasn't working automatically.
You can try a patch like this:

diff --git a/staging/src/k8s.io/kubectl/pkg/kuberc/kuberc.go b/staging/src/k8s.io/kubectl/pkg/kuberc/kuberc.go
index 03c6a2ef9b9..4b156c0f78e 100644
--- a/staging/src/k8s.io/kubectl/pkg/kuberc/kuberc.go
+++ b/staging/src/k8s.io/kubectl/pkg/kuberc/kuberc.go
@@ -194,7 +194,7 @@ func (p *Preferences) applyAliases(rootCmd *cobra.Command, kuberc *config.Prefer
 	var commandName string // first "non-flag" arguments
 	var commandIndex int
 	for index, arg := range args[1:] {
-		if !strings.HasPrefix(arg, "-") {
+		if !strings.HasPrefix(arg, "-") && !strings.HasPrefix(arg, "__complete") {
 			commandName = arg
 			commandIndex = index + 1
 			break

Let me know if you want more details.

[ardaguclu]

Many thanks @marckhouzam for your helping (as always :) ). I'll test soon.