hosts/osmium: deploy nixfiles inputs update script

hosts/osmium/configuration.nix

@@ -5,6 +5,8 @@
     [
       ./hardware-configuration.nix
       ../../configuration/proxmox-vm
+
+      ./nixfiles-updated-inputs.nix
     ];
 
   boot.loader.grub.enable = true;

hosts/osmium/nixfiles-updated-inputs.nix

@@ -0,0 +1,21 @@
+{ config, pkgs, ... }:
+
+{
+  systemd.services.nixfiles-updated-inputs = {
+    environment = {
+      GIT_SSH_COMMAND = "ssh -o UserKnownHostsFile=${pkgs.writeText "known_hosts" "git.clerie.de ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIHQDwfRlw6L+pkLjXDgW2BUWlY1zNEDtVhNEsClgqaL"} -i %d/nixfiles-updated-inputs-ssh";
+      # nix likes a home directory to place the cache there
+      HOME = "/var/lib/nixfiles-updated-inputs";
+    };
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = pkgs.nixfiles-updated-inputs + "/bin/nixfiles-updated-inputs";
+      StateDirectory = "nixfiles-updated-inputs";
+      WorkingDirectory = "/var/lib/nixfiles-updated-inputs";
+      DynamicUser = true;
+      # this sets the correct file permissions for the ssh key because we use DynamicUser
+      LoadCredential = "nixfiles-updated-inputs-ssh:${config.age.secrets."nixfiles-updated-inputs-ssh".path}";
+    };
+    startAt = "*-*-* 03:03:00";
+  };
+}