I lead/contribute to several open source projects. I know that the code is getting used, but I have no data regarding number of users, number of installations, or usage frequency. I'm looking for ideas about how to collect such data.
Here's what I've considered:
Github stars or Flattr/Patreon contributions. These require logins for those services, which may not apply in my case. In addition, I don't want financial rewards.
Mailing list messages and issue tracking activity. Both of these seem like poor proxies for the desired stats.
Phone home UDP pings. Users (and I) typically dislike tracking. Unfortunately, this does seem like the best way to get the data I want. (I would be happy to provide a kill switch for concerned users.) Also, it would be nice to have a reliable receiver with analytics, and I don't want to build that.
User satisfaction services. UserVoice, UserResponse, GetSatisfaction, etc are overkill for me.
So, the question: What do other open source projects do? I'm particularly interested in the case of a Python package that's used by other tools, but this would apply libraries in any language.