This commit allows us to get shell completion for kubectl plugins.
For example, with the use of a plugin named 'kubectl-krew', completing
kubectl k<tab>
will include 'krew' in the list of possible completions.
Because the shell completion scripts are generated by Cobra, this commit
took the approach of registering every plugin as a Cobra command. This
makes Cobra aware of each plugin command when generating completions.
For efficiency, searching for plugins and registering them as Cobra
commands is only done when needed, which is when calling the
'kubectl completion' command in the case of bash, as it includes all
commands and subcommands directly in the bash generated script.
For the other shells, this will need to be done for the
'kubectl __complete' command, in a follow-up command.
Co-authored-by: Marc Khouzam <marc.khouzam@montreal.ca>
Signed-off-by: Kazuki Suda <kazuki.suda@gmail.com>
Kubernetes-commit: 3db3ff53cdf4b106365c5de9194153fc371868a7
9c405e27d0