We used Docker sort of early on, and got out of it around v1.6. Many problems that you had to work around yourself, but the one you just reminded me of was the repos: There was Dockerhub, a third-party place without 100%(-ish) uptime, and two serve-your-own, one of which was a black box you could never delete from, and the other had stamped "NOT FOR PRODUCTION USE" in big letters on its github page.

I remember one of the engineers giving a talk, saying that the problem they had was growing too big too quickly - they didn't have time to properly work out the base architecture in the early days.