epyc: add android cache

hosts/epyc.nix

@@ -10,6 +10,7 @@ in
     ../modules/iperf-server.nix
     ../modules/hypervisor.nix
     ../modules/hydra/coordinator.nix
+    ../modules/android-cache.nix
     ../modules/users/friends.nix
   ];
 

modules/android-cache.nix

@@ -0,0 +1,13 @@
+{ lib, ... }:
+let
+  mirrors = {
+    "https://android.googlesource.com" = "/var/lib/src/aosp/mirror";
+    "https://github.com/LineageOS" = "/var/lib/src/lineageos/LineageOS";
+  };
+in
+{
+  nix.envVars.ROBOTNIX_GIT_MIRRORS = lib.concatStringsSep "|" (lib.mapAttrsToList (local: remote: "${local}=${remote}") mirrors);
+
+  # Also add local mirrors to nix sandbox exceptions
+  nix.sandboxPaths = lib.attrValues mirrors;
+}