If I want to use ssh -A every time I do a Git push, I need to add the remote host to my ~/.ssh/config.

All the words and code for this website are in a Git repo. The canonical copy of the repo is a bare repository on my Mac mini, which has a post-receive hook that builds a copy of the site and uploads the files to my web server.

If I’m working on my Mac mini, this works fine – the SSH key for the web server is in my local keychain, so when I push the post-receive hook can upload to the web server.

If I’m working on my laptop, I need some extra config – when I push to the Mac mini, the post-receive hook can’t get the SSH key from the Mac mini’s keychain, and publishing to the web server fails.

I’ve fixed this by adding an entry to ~/.ssh/config on my laptop:

Host phaenna-mac-mini
    HostName phaenna-mac-mini
    User alexwlchan
    ForwardAgent yes

This tells my laptop that any time it opens an SSH connection to phaenna-mac-mini, it should use SSH agent forwarding. (The equivalent of running ssh -A for a manual connection.)

This means my laptop’s SSH keys get forwarded to the Mac mini, and they’re available to the post-receive hook. My laptop can SSH to my web server, so the forwarded keys allow the post-receive hook to publish correctly.

This config includes any SSH connection, including those created by Git. I thought maybe I’d need config in every repo, but the global SSH config file seems to be enough.