VEGAS: provide a Nix binary cache

hosts/VEGAS/services/nix/binary-cache.nix

@@ -0,0 +1,18 @@
+{ config, tools, ... }:
+with tools.nginx;
+let
+  addrSplit' = builtins.split ":" config.services.minio.listenAddress;
+  addrSplit = builtins.filter builtins.isString addrSplit';
+  host' = builtins.head addrSplit;
+  host = if host' == "" then "127.0.0.1" else host';
+  port = builtins.head (builtins.tail addrSplit);
+in
+{
+  services.nginx.virtualHosts."cache.${tools.meta.domain}" = vhosts.basic // {
+    locations = {
+      "= /".return = "302 /404";
+      "/".proxyPass = "http://${host}:${port}/nix-store$request_uri";
+      "/nix/store".proxyPass = "http://127.0.0.1:${builtins.toString config.services.nar-serve.port}";
+    };
+  };
+}

hosts/VEGAS/system.nix

@@ -29,6 +29,7 @@
       ./services/nfs
       ./services/mail
       ./services/matrix
+      ./services/nix/binary-cache.nix
       ./services/object-storage
       ./services/warehouse
       ./services/websites