For those who want a less all-or-nothing migration path from Heroku, might I suggest looking into Cloud Foundry? Several of the buildpacks (most notably Ruby) a

For those who want a less all-or-nothing migration path from Heroku, might I suggest looking into Cloud Foundry? Several of the buildpacks (most notably Ruby) are derived from Heroku's upstream repos. If you decide later that you want to build your own containers, Cloud Foundry has you covered there too, with a pathway for Docker images to be placed, launched and monitored on an equal basis with buildpack droplets. I'm biased, of course. I work for Pivotal, which donates the majority of engineering time to Cloud Foundry.