@rhizogrip/spore-plugin-ssh

SSH for spores: the keys a host's ssh-agent holds, which a spore's ssh and git can use and never read. For any SSH service — a forge, GitHub, a server.

npm i -g @rhizogrip/spore-plugin-ssh
spore plugin allow ssh socket=/run/user/$(id -u)/spore-ssh-agent.socket

The socket is the one spore service define ssh-agent sets up, below; it prints this line.

A spore uses it once its spore.cmk says plugins: [ssh]. Its agent is given SSH_AUTH_SOCK, pointing at the agent below, and $SPORE_SSH — also GIT_SSH, so git uses it — an ssh that keeps known hosts and config in the workspace's home/.ssh/, since ssh finds its own through the account's home, which the sandbox refuses. It reads how to use them in plugins/ssh.md.

The agent, on the host

The keys stay in ~/.config/spore/ssh/, beside config.json, which the sandbox never grants; only the agent's socket reaches a spore, and the ssh-agent protocol signs with a key and never hands one out. spore service runs the agent, as the user spores run under:

mkdir -m 700 -p ~/.config/spore/ssh
ssh-keygen -t ed25519 -N '' -C 'git.example.org as spore-bot' -f ~/.config/spore/ssh/spore-bot
spore service define ssh-agent        # checks the keys, writes the unit, prints the enable line
spore service start ssh-agent && spore service enable ssh-agent

Every private key in that folder is loaded when the service starts. A key has no passphrase — nobody is there to type one — and define refuses one that has. To add or retire a key, put it in the folder or take it out, then spore service restart ssh-agent.

What a spore can do with a key is decided here, where it cannot change it:

• Which keys: what is in ~/.config/spore/ssh/. The comment is what the agent sees in ssh-add -l, so say there what the key is for.
• Which repositories: give the key its own account on the service, with access to what the spore should touch and nothing else, and protect the branches it should not push to.

The socket is shared on trust. Any process of that user can connect to it — every spore it runs, whether its definition names this plugin or not. plugins: [ssh] says which spores are told about the keys, not which can reach them. Load only keys you would hand to every spore of that user.