The announcement of Rocket by CoreOS was perceived by many to be a direct challenge to Docker, particularly as it came on the eve of DockerCon Europe and threatened to overshadow news coming out at the event. Docker, Inc. CEO Ben Golub was quick to fire back with his ‘initial thoughts on the Rocket announcement’. This piece isn’t about the politics of ecosystems and VC funded startups, which I’ll leave to Colin Humphreys (and note an excellent response from Docker Founder and CTO Solomon Hykes). It also isn’t about managing open source community, which I’ll leave to Matt Asay. Here I want to look at systemd, which lies at the heart of the technical arguments.
There’s been an unholy war raging through the Linux world over systemd for some time. Pretty much everything on a system gets touched by what is selected as the first process on a system and how that impacts everything getting started up. People care a lot about this stuff, and the arguments have been passionate. Nevertheless, Mark Shuttleworth conceding defeat on behalf of Ubuntu marked the last major distribution going all in on systemd. Unless forks like Devuan become successful it’s going to be pretty hard to get Linux in a couple of years time without getting systemd as part of it.
Since CoreOS is a shiny new distribution, they went for systemd from the beginning. It was an obvious move, and frankly anything else would seem pretty ridiculous. Docker however, is a child of a different generation. Docker couldn’t align itself with systemd and then wait around for for it to become popular.