sops: fix key path for darwin

.sops.yaml

@@ -1,8 +1,9 @@
 # XXX: missing: macbook, thinknix?, at some point mobile
 keys:
   - &admins age1q80zzsgglj438verw74jghezn8ndpqldvg0mfxzwtaq4v5h7apusqysavz #framenix
+  - &workmac age1fft2ynhazjwtjmxsvt37qervtekktdln2968gjp4vcp5sp3jeg5segkz3x #workmac
   # Generate AGE keys from SSH keys with:
-  # nix-shell -p ssh-to-age --run 'ssh some.example.com /etc/ssh/ssh_host_ed25519_key.pub | ssh-to-age'
+  # nix-shell -p ssh-to-age --run 'ssh some.example.com cat /etc/ssh/ssh_host_ed25519_key.pub | ssh-to-age'
   - &machine_framenix age1kx93vp8l8jd6kz0kvk379udr5z8a9t6946w0ff5t9a2esn47nqzqlfzvwe
 creation_rules:
   # per-host secrets for host specific ones, but for service modules we could store and manage them also per module scope
@@ -15,5 +16,6 @@ creation_rules:
     key_groups:
       - age:
         - *admins
+        - *workmac
         - *machine_framenix
 

darwin/sops.nix

@@ -6,7 +6,7 @@
 }:
 {
   sops = {
-    age.sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
+    age.keyFile = "/Users/os/Library/Application Support/sops/age/keys.txt";
     defaultSopsFile = lib.mkDefault ./secrets.yaml;
     defaultSopsFormat = "yaml"; # is the default. ini had some template rendering issues in practice
   };

home/modules/sops.nix

@@ -1,7 +1,32 @@
-{ inputs, ... }:
 {
+  inputs,
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  homeKeys =
+    if pkgs.stdenv.isDarwin then
+      "/Users/${config.home.username}/Library/Application Support/sops/age/keys.txt"
+    else
+      "/home/${config.home.username}/.config/sops/age/keys.txt";
+in
+lib.mkMerge [
+  {
+    home.ensureDirs."${builtins.dirOf homeKeys}".mode = "0700";
     sops = {
       age.keyFile = "/home/user/.age-key.txt"; # must have no password!
       # deliberately not setting `defaultSopsFile` because there is no clear file-hostname-mapping. Each separate home config has to configure this explicitly.
     };
-}
+  }
+  # linux machines: assumption: there is an OpenSSH server of which we are able to use the hostkey, like at the NixOS module. The `keyDir` is only used for the private admin key.
+  (lib.mkIf pkgs.stdenv.isLinux {
+    sops.age.sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
+  })
+
+  # darwin: no SSH server, no hostkey => let's use the `keyDir` key both for encryption and decrpytion
+  (lib.mkIf pkgs.stdenv.isDarwin {
+    sops.age.keyFile = homeKeys;
+  })
+]