make the multi-node vm tests a bit more reliable

without these changes the tests will very repeatably (although not very
reliably) wedge in our runs. the ssh command starts, opens a sessions,
does something, the session closes again, but the test does not move on.
adding *just* the redirect and not the unit waits is not sufficient
either, it needs both. this feels like a bug in the nixos testing
framework somewhere, but digging that far is not in the cards right now.

Change-Id: Idab577b83a36cc4899bb5ffbb3d9adc04e83e51c

1 files changed, 7 insertions, 3 deletions

diff --git a/tests/nixos/nix-copy-closure.nix b/tests/nixos/nix-copy-closure.nix
index 66cbfb033..cd25fbbd0 100644
--- a/tests/nixos/nix-copy-closure.nix
+++ b/tests/nixos/nix-copy-closure.nix
@@ -40,6 +40,11 @@ in {
       "${pkgs.openssh}/bin/ssh-keygen", "-t", "ed25519", "-f", "key", "-N", ""
     ], capture_output=True, check=True)
 
+    server.succeed("systemctl start network-online.target")
+    client.succeed("systemctl start network-online.target")
+    server.wait_for_unit("network-online.target")
+    client.wait_for_unit("network-online.target")
+
     client.succeed("mkdir -m 700 /root/.ssh")
     client.copy_from_host("key", "/root/.ssh/id_ed25519")
     client.succeed("chmod 600 /root/.ssh/id_ed25519")
@@ -47,9 +52,8 @@ in {
     # Install the SSH key on the server.
     server.succeed("mkdir -m 700 /root/.ssh")
     server.copy_from_host("key.pub", "/root/.ssh/authorized_keys")
-    server.wait_for_unit("sshd")
-    client.wait_for_unit("network.target")
-    client.succeed(f"ssh -o StrictHostKeyChecking=no {server.name} 'echo hello world'")
+    server.wait_for_unit("sshd.service")
+    client.succeed(f"ssh -o StrictHostKeyChecking=no {server.name} 'echo hello world' >&2")
 
     # Copy the closure of package A from the client to the server.
     server.fail("nix-store --check-validity ${pkgA}")