Every time I fire up a zsh shell terminal in gnome-shell I can’t add my ssh key to an existing ssh-agent instance.

$ ssh-add
Could not open a connection to your authentication agent.

The gnome-keyring-daemon is running, but it just doesn’t seem to set the environment variable SSH_AUTH_SOCK.

I’d have to run ssh-agent and start one listening on a temporary socket and pass the environment settings around terminal sessions. Turns out this is a known issue and the fix is relatively easy.

For zsh add the environment variable to your ~/.zshrc

export SSH_AUTH_SOCK=/run/user/$(id -u)/keyring/ssh

Now any call to ssh-add in a terminal works as expected.

You might want to do the same for other shells in ~/.profile etc.