We just pushed code, compiled, and hotloaded... Pretty much ignoring the release files; we had them, but I think the contents weren't correct and we never changed the release numbers, etc.

For otp updates, we would shutdown beam in an orderly fashion, replace the files, and start again. (Potentially installing the new one before shutting down, I can't remember).

Post facebook, more of boring OS packages and slow rollouts than hotloading.

Thank you for providing the information, its always good to see how others were rolling out updates.