Docker Alpine /bin/sh apk not found

I ran into something like this. It completely blew my mind, and I was questioning my sanity for a bit until I realized that /sbin wasn't in my container's PATH.

# interactive session
PATH="${PATH}:/sbin"

# Dockerfile
ENV PATH="${PATH}:/sbin"

If you type command -v apk in an interactive session in your container's base image and compare that directory with the container's $PATH that should get you squared away.

If command -v apk doesn't work for you, you could try to find it via

find / -name apk -type f -exec dirname "{}" ";"

To the best of my knowledge this is always in /sbin. However you get there, just ensure that the apk binary's location is part of $PATH

TL;DR - If you see this error, ensure that your executable's dirname is in your $PATH