uvms: init app urls, kinda

pkgs/uvms/uvms.py

@@ -13,6 +13,7 @@ import json
 import re
 from argparse import ArgumentParser
 from contextlib import contextmanager, closing, ExitStack
+from urllib import urlparse
 
 
 parser = ArgumentParser("supervise-vm")
@@ -517,11 +518,24 @@ def main(args, args_next, cleanup, ps):
 
     app_paths = []
     for a in args.app:
+        a = urlparse(a)
+        nix_file = None
+        attr = None
+        if a.scheme == "":
+            nix_file = "<nixpkgs>"
+            attr = a.path
+        elif a.scheme == "getexe":
+            nix_file = a.netloc or "./."
+            attr = a.path.lstrip("/")
+        else:
+            raise RuntimeError("Unknown app url", a)
+        assert nix_file is not None, a
+        assert attr is not None, a
         out_path = ps.exec(
             "nix-build",
-            "<nixpkgs>",
+            nix_file,
             "-A",
-            a,
+            attr,
             "--no-out-link",
             capture_output=True,
             text=True,