In my ongoing quest to make life difficult for myself, I was working with Juju in a zsh termnial environment. Juju’s tab completion is great, and I rely on it heavily. It seems to not work out of the box on zsh.
Here’s how I got it working: (in an Ubuntu Bionic env, and also in a Win10/WSL/Bionic env)
At the end of ~/.zshrc add these lines:
autoload -U +X compinit && compinit autoload -U +X bashcompinit && bashcompinit source /usr/share/bash-completion/completions/juju
And restart your shell. I hope it works for you!