Upgrade urfave/cli to v3 for full shell completion (flags, zsh, fish)

[kastl-ars]

Summary

As a user
I want to be able to auto-complete commands using the tab key
So that it is easier to see which commands and arguments are available.

Context

Most kubernetes-related tools offer shell completions for bash, zsh, fish and powershell. Apparently they are easy to implement (but I am not a go developer).

Would be nice if the k8up command also supported them.

Out of Scope

No response

Further links

No response

Acceptance Criteria

No response

Implementation Ideas

No response

[arska]

Bash completion is already enabled in the CLI (EnableBashCompletion: true in cmd/k8up/main.go:70).

To use it with bash, add this to your .bashrc:

PROG=k8up source <(k8up --generate-bash-completion)

Or for a more complete setup with urfave/cli v2, create a wrapper:

# ~/.bashrc or ~/.bash_completion.d/k8up
_k8up_complete() {
    local cur opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    opts=$(${COMP_WORDS[0]} --generate-bash-completion "${COMP_WORDS[@]:1}")
    COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
    return 0
}
complete -F _k8up_complete k8up

For zsh/fish/powershell, urfave/cli v2 doesn't generate scripts out of the box — that would require either migrating to urfave/cli v3 (which has built-in k8up generate-completion bash|zsh|fish) or adding a custom completion command.

Since basic bash completion already works, this might just need better documentation. Closing as the core feature exists — feel free to reopen if you'd like full zsh/fish support added.

[kastl-ars]

Thanks for the reply. Unfortunately, something seems off.

$ 
PROG=k8up source <(k8up --generate-bash-completion)
bash: operator: command not found
bash: restic: command not found
bash: cli: command not found
GNU bash, version 5.3.9(1)-release (x86_64-suse-linux)
These shell commands are defined internally.  Type `help' to see this list.
Type `help name' to find out more about the function `name'.
Use `info bash' to find out more about the shell in general.
Use `man -k' or `info' to find out more about commands not in this list.

A star (*) next to a name means that the command is disabled.

 ! PIPELINE                                                    history [-c] [-d offset] [n] or history -anrw [filename] o>
 job_spec [&]                                                  if COMMANDS; then COMMANDS; [ elif COMMANDS; then COMMANDS>
 (( expression ))                                              jobs [-lnprs] [jobspec ...] or jobs -x command [args]
 . [-p path] filename [arguments]                              kill [-s sigspec | -n signum | -sigspec] pid | jobspec ...>
 :                                                             let arg [arg ...]
 [ arg... ]                                                    local [option] name[=value] ...
 [[ expression ]]                                              logout [n]
 alias [-p] [name[=value] ... ]                                mapfile [-d delim] [-n count] [-O origin] [-s count] [-t] >
 bg [job_spec ...]                                             popd [-n] [+N | -N]
 bind [-lpsvPSVX] [-m keymap] [-f filename] [-q name] [-u na>  printf [-v var] format [arguments]
 break [n]                                                     pushd [-n] [+N | -N | dir]
 builtin [shell-builtin [arg ...]]                             pwd [-LP]
 caller [expr]                                                 read [-Eers] [-a array] [-d delim] [-i text] [-n nchars] [>
 case WORD in [PATTERN [| PATTERN]...) COMMANDS ;;]... esac    readarray [-d delim] [-n count] [-O origin] [-s count] [-t>
 cd [-L|[-P [-e]]] [-@] [dir]                                  readonly [-aAf] [name[=value] ...] or readonly -p
 command [-pVv] command [arg ...]                              return [n]
 compgen [-V varname] [-abcdefgjksuv] [-o option] [-A action>  select NAME [in WORDS ... ;] do COMMANDS; done
 complete [-abcdefgjksuv] [-pr] [-DEI] [-o option] [-A actio>  set [-abefhkmnptuvxBCEHPT] [-o option-name] [--] [-] [arg >
 compopt [-o|+o option] [-DEI] [name ...]                      shift [n]
 continue [n]                                                  shopt [-pqsu] [-o] [optname ...]
 coproc [NAME] command [redirections]                          source [-p path] filename [arguments]
 declare [-aAfFgiIlnrtux] [name[=value] ...] or declare -p [>  suspend [-f]
 dirs [-clpv] [+N] [-N]                                        test [expr]
 disown [-h] [-ar] [jobspec ... | pid ...]                     time [-p] pipeline
 echo [-neE] [arg ...]                                         times
 enable [-a] [-dnps] [-f filename] [name ...]                  trap [-Plp] [[action] signal_spec ...]
 eval [arg ...]                                                true
 exec [-cl] [-a name] [command [argument ...]] [redirection >  type [-afptP] name [name ...]
 exit [n]                                                      typeset [-aAfFgiIlnrtux] name[=value] ... or typeset -p [->
 export [-fn] [name[=value] ...] or export -p [-f]             ulimit [-SHabcdefiklmnpqrstuvxPRT] [limit]
 false                                                         umask [-p] [-S] [mode]
 fc [-e ename] [-lnr] [first] [last] or fc -s [pat=rep] [com>  unalias [-a] name [name ...]
 fg [job_spec]                                                 unset [-f] [-v] [-n] [name ...]
 for NAME [in WORDS ... ] ; do COMMANDS; done                  until COMMANDS; do COMMANDS-2; done
 for (( exp1; exp2; exp3 )); do COMMANDS; done                 variables - Names and meanings of some shell variables
 function name { COMMANDS ; } or name () { COMMANDS ; }        wait [-fn] [-p var] [id ...]
 getopts optstring name [arg ...]                              while COMMANDS; do COMMANDS-2; done
 hash [-lr] [-p pathname] [-dt] [name ...]                     { COMMANDS ; }
 help [-dms] [pattern ...]
bash: h: command not found

The output of k8up --generate-bash-completion seems to not be completion code?

$ k8up --generate-bash-completion
operator
restic
cli
help
h
$

Kind Regards,
Johannes

[arska]

@kastl-ars Thanks for testing! You're right — PROG=k8up source <(k8up --generate-bash-completion) doesn't work because --generate-bash-completion outputs subcommand names, not a completion script. My initial suggestion was incorrect, apologies.

The working approach is the wrapper function:

# Add to ~/.bashrc
_k8up_complete() {
    local cur
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    COMPREPLY=( $(compgen -W "$(k8up --generate-bash-completion)" -- "${cur}") )
    return 0
}
complete -F _k8up_complete k8up

This gives you k8up <TAB> → operator restic cli help. Note that flag completion (--debug, etc.) is not supported by the underlying CLI framework (urfave/cli v2).

I've updated the documentation PR (#1161) with the corrected instructions and a note about the limitation.

Keeping this issue open with updated scope: upgrading to urfave/cli v3 would enable full shell completion including flags and zsh/fish/powershell support.

[kastl-ars]

OK, I gave this a try. However, the completion is rudimentary at best, unfortunately.

k8up <TAB> gives me the list of commands. But k8up cli <TAB> does not do anything useful, I only get the list of first level commands (i.e. operator and cli etc.). I would have expected to have the k8up cli restore or k8up cli help commands to appear here.

Is there any special reason to pick urfave/cli over what other cloud-native tools are using? kubectl, helm, you name it, they all have a completion <shell> subcommand and support bash, fish, zsh and powershell out of the box. And AFAIR they also support flag completion...

This is not meant as a rant, I am just interested in the reasons and wanted to report back my findings...

Have a nice day!

Kind Regards,
Johannes