kubectl-sh-wrapper

#!/bin/bash
# kubectl-sh-wrapper (part of ossobv/vcutil) // wdoekes/2019 // Public Domain
#
# Wrapper to call custom kubectl shell wrapper scripts. By also calling it
# kubectl, we get a certain amount of tab-completion support.
#
# IMPORTANT: To make this work, you'll need to manually symlink this.
#
#   ln -s /usr/bin/kubectl-sh-wrapper /usr/local/bin/kubectl
#
# And the real kubectl needs to be available as /usr/bin/kubectl.
#
# Provides access to:
#   --sh-bash: calls kubectl-sh-bash, sets shell $LINES/$COLUMNS, execs bash
#   --sh-secret: calls kubectl-sh-secret, helps with opaque secrets
#
# Examples:
#
#   kubectl --help # regular behaviour
#
#   kubectl exec --sh-bash -it PODNAME  # goes through kubectl-sh-bash
#
test -z "${BASH_VERSION}" && echo "$0: requires bash" >&2 && exit 1

# Get first kubectl command from $PATH that is not us; in a bash-y fashion
# without spawning too many subprocesses. Note that we might call $KUBECTL in
# the wrapper scripts directly.
while IFS='' read -d $'\n' l; do
    test "$l" != "${BASH_SOURCE[0]}" && KUBECTL=$l && break
done < <(which -a kubectl)

# Look through args and find --sh-* shell plugins.
script=
declare -a ARGS
for var in "$@"; do
    # Catch custom commands:
    if [[ "$var" == --sh-bash ]]; then
	script=kubectl-sh-bash
    elif [[ "$var" == --sh-secret ]]; then
        script=kubectl-sh-secret
    elif [[ "$var" == --sh-* ]]; then
        echo "Usage: $0 [...] --sh-* [...]" >&2
        echo "Where --sh-* is one of:" >&2
        echo "  --sh-bash: sets LINES/COLUMNS for kubectl exec" >&2
        echo "  --sh-secret: helps with opaque secret handling" >&2
        exit 1
    else
        ARGS[${#ARGS[@]}]="$var"
    fi
done

# Found a script? Source it; they're bash commands too.
if test -n "$script"; then
    set -- "${ARGS[@]}"  # update argv
    source "$(command -v "$script")"
    exit $?
fi

# Call the real kubectl.
exec "$KUBECTL" "${ARGS[@]}"