Add completion command

[feiskyer]

For #212.

Note: only includes subcommands and global flags now. The completion for each subcommand is not included, need to figure out how to process it.

Generate shell completion code (works for both bash and zsh):

# crictl completion
_cli_bash_autocomplete() {
    local cur opts base
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    opts="attach
create
exec
version
images
inspect
inspecti
inspects
logs
port-forward
ps
pull
runs
rm
rmi
rms
sandboxes
start
info
stop
stops
update
config
stats
completion
help
h
--config
--debug
--image-endpoint
--runtime-endpoint
--timeout
--help
--version"
    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
    return 0
}

complete -F _cli_bash_autocomplete crictl

Usage

source <(crictl completion)

[Random-Liu]

Can we use this? https://github.com/urfave/cli#bash-completion

[feiskyer]

@Random-Liu This PR works same way, but do not require users to source another autocomplete/bash_autocomplete file.

[feiskyer]

ping @Random-Liu

[Random-Liu]

/lgtm