The exact protocol was kept secret. But the alliance itself was no secret at all -- the whole world knew about it, and there were open "victory parades" in major cities like Brest, Lwów, and Grodno. They even built elaborate "Victory Arches" with swastikas and red stars side by side.

If that doesn't count as a signal of "enthusiasm", I don't know what does.

https://en.wikipedia.org/wiki/German%E2%80%93Soviet_military...