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I'm biased, because I worked at WhatsApp, but it may be one of the most famous users of Erlang... and from its start until when I left (late 2019) I think we only hired three people with Erlang experience. Everyone else who worked in Erlang learned on the job.

We seemed to do pretty well, although some of our code/setup wasn't very idiomatic (for example, I'm pretty sure we didn't use the Erlang release feature properly at all)

[worthless-trash]

After you've done releases a few times, it ends up being quite easy. The biggest issues I had was complete release (aka erlang itself) updates.

Admittedly, I didn't have a whole company core product riding on my upgrades.

[toast0]

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.

[worthless-trash]

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