Gathering Chef Usage Data 2017-07-26

A proposed Chef RFC currently sitting in the review queue revolves around gathering anonymized usage information about Chef and some of the Chef ecosystem tools. I think this proposal needs some more eyeballs on it from the Chef community so hopefully this will encourage some of you to weigh in by commenting on the pull request. Usual disclaimer on time-sensitive posts, if you found this via Google some time in the future, it might not apply anymore.

Why gather user data?

As both a Chef maintainer and a cookbook developer, I have an interest in this user data. A big problem for Chef, as with almost all open-source projects, has been that we know almost nothing about how the things we write actually get used. We have some signaling from people asking questions on Slack or filing bug reports, but this is both very coarse-grained and ignores a huge majority of users. This makes it very hard to know how to allocate time and resources, both of which are in short supply (again, same as in any other open-source project, none of this is unique to Chef).

Having some kind of automated data collection would give us a huge boost in knowing what things are popular and should be given more attention, and which were maybe failed experiments or are broken in some way we haven’t been made aware of. This has happened many times over the years, we maintainers assuming something was no longer used, and finding out only after the release that we were wrong (obligatory xkcd).

As a concrete example, Test Kitchen supports a lot of driver plugins. There are two Docker-based drivers, my kitchen-docker and Sean’s kitchen-dokken. We’ve been trying to steer people towards Dokken as a better user experience for simple use cases, but as the maintainer of kitchen-docker I have no way to judge how common the complex or advanced cases are, or even the rough distribution of users for docker vs dokken. This makes it very hard to know what kinds of things to support in each and (probably) leads to worse software for everyone.

Why not to gather user data?

The main reason to not gather user data is the risk of said data ending up used for nefarious purposes. A simple case might be someone finding a password that was incorrectly pasted in the wrong section of a config file, but more subtle issues can arise like searching for users with old versions of ChefDK which have a known vulnerability in their OpenSSL. To counter this we have two main lines of defense: first is that all data is stored anonymously with a session identifier reset every ten minutes. Second is that we plan to make sure all data is public from the start, so we don’t have to wait for an inevitable leak to realize there is a problem with the data.

Anonymous data is never perfect though, and the rise in public data sets has lead to new advances in de-anonymization. We will do our best to keep on top things, but there will always be some passive risk. Therefore any data collection must be optional with both per-user and per-project configuration, but more on that below. Also it is worth restating here that only workstation commands are being considered for this. chef-client, chef-solo, and the whole of Chef Server do not and will not collect data of any kind.

As a secondary thing, there is almost always a PR storm any time an open-source project brings up this topic. I am probably contributing to this, though hopefully with enough positive to outweigh any trolls I bring in to the discussion. Still, this could end up being a harm to users if we have to fight FUD for a while, so that should be considered. All planning and development of this feature is being done in the open, which also hopefully helps offset the “sky is falling” crowd.

Opt In or Out

As mentioned above, all data collection will be 100% optional, but that brings up the question of how to control it. We will need to pick a default yes/no, as well as how to tell the user about this whole thing.

Being silently disabled by default is effectively a non-option since we would get so little data as to not be worth the effort to build the whole system, and being silently enabled by default would (I think rightly) be viewed by many users as a breach of trust and overstepping our bounds as a project.

I think the best approach is a middle ground, off by default, but the first time you run any instrumented command it asks if you want to allow telemetry with a default of “yes” if you hammer on the enter key. This will mean we don’t get data from TTY-less systems like CI servers, but is otherwise a balance between user expectations and data quality. The opt-out will always be available afterwards via a command like chef telemetry disable or something, or you can manually touch the .chef/no_telemetry file (which can be checked in to source control to permanently disable things for a project).

We would love to hear from you if you have thoughts on this though.

Prior Art

The proposed RFC covers this a bit but I wanted to dive in a bit more on some ways other projects have handled this, mostly just to point out that this can be done without the world ending.

Both Chrome and Firefox (and probably Safari but who knows with them) gather anonymized usages statistics as well as crash reports, and I don’t think I’ve ever seen complaints about either. Firefox crash reports in particular, I know several people that used to be on the team that managed that system and heard from them frequently about how useful it was to the Firefox development team.

Debian’s PopCon, Ubuntu’s Apport, and Fedora’s Retrace projects all gather some level of usage information about packages (the latter two only on crashes) and have been mostly uncontroversial in my experience (other than complaints about apport from Python devs because it does weird stuff to the load path but that’s neither here nor there). PopCon is mostly just for fun, but the error collection has been cited as useful by a bunch of Ubuntu/Fedora projects.

Homebrew added similar tracking via Google Analytics last year, and definitely had some growing pains with it initially. After the initial flurry of fixes to what was being collected, it seems to be going okay, though the Homebrew team has been somewhat gruff in dealing with complaints which might indicate that they get a lot of flak behind the scenes.

Overall it seems like a lot of bigger projects add this kind of tracking to little fanfare, especially desktop applications (like ChefDK).

Next Steps

Hopefully by now I’ve encouraged you to go drop us a line on the pull request. We really do want to make sure we only move forward with this if it is in the best interests of users and to do that we need to know what your interests are. If anyone wants to provide feedback anonymously or has questions not answered here, you can always reach me at

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