Add declarative ssh known hosts

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/elara/configs/git/default.nix

@@ -1,4 +1,7 @@
-{ ... }:
+{ inputs, system, ... }:
+let
+  selfPkgs = inputs.self.packages.${system};
+in
 {
   sops.secrets."ssh/sas/key" = {
     sopsFile = ../../../../secrets/sas/secrets.yaml;
@@ -6,15 +9,22 @@
     path = "/root/.ssh/ssh_sas_ed25519_key";
   };
 
-  programs.ssh.extraConfig = ''
-    Host github.com
-      User git
-      HostName github.com
-      IdentityFile /root/.ssh/ssh_sas_ed25519_key
+  programs.ssh = {
+    extraConfig = ''
+      Host github.com
+        User git
+        HostName github.com
+        IdentityFile /root/.ssh/ssh_sas_ed25519_key
 
-    Host gitlab.sas.com
-      User git
-      HostName gitlab.sas.com
-      IdentityFile /root/.ssh/ssh_sas_ed25519_key
-  '';
+      Host gitlab.sas.com
+        User git
+        HostName gitlab.sas.com
+        IdentityFile /root/.ssh/ssh_sas_ed25519_key
+    '';
+
+    knownHostsFiles = with selfPkgs; [
+      ssh-known-hosts-github
+      ssh-known-hosts-sas-gitlab
+    ];
+  };
 }