Emacs daemon doesn't see SSH_AUTH_SOCK from gnupg

[shosti]

Issue description

Since #48772, emacs run through services.emacs doesn't see SSH_AUTH_SOCK set by programs.gnupg.agent.enableSSHSupport. This is problematic because packages like magit will not use the correct SSH agent.

SSH_AUTH_SOCK does work correctly in 18.09; this is a regression on master.

Steps to reproduce

1. Put the following in your config:

programs.gnupg.agent = {
  enable = true;
  enableSSHSupport = true;
}

services.emacs.enable = true;

2. emacsclient -e '(getenv "SSH_AUTH_SOCK")'

The result will be nil. (Note that if you start emacs from a shell and evaluate the above expression, the result will be correct.)

Technical details

• system: "x86_64-linux"
• host os: Linux 4.19.20, NixOS, 19.03pre169108.36f31600749 (Koi)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.2
• channels(root): "nixos-19.03pre169108.36f31600749"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

[FlorianFranzen]

Does systemctl --user import-environment SSH_AUTH_SOCK help with the issue? You might have to restart emacs with systemctl --user restart emacs to see the effect.

[shosti]

The root cause is clear: the above PR swapped extraInit with interactiveShellInit, which isn’t sourced for systemd daemons. I added the SSH_AUTH_SOCK portion to extraInit in my configuration.nix, which fixes the issue, but it’s pretty clear to me that SSH_AUTH_SOCK should be set in both interactive shells and systemd daemons.

[shosti]

PR to fix open at #56254, does that seem like a reasonable approach?