Curious if the folks looking for an "open source Heroku", whow found Flynn, also looked at open source Cloud Foundry... and what turned them off from CF.
I've been a part of running Cloud Foundry in production, both on-prem and in AWS. From a user (developer) perspective, it's pretty magical: throw an app at it, and it runs. On the infrastructure side, the footprint is huge and has a ton of moving parts. If you have an SRE-type team to keep it alive, and your organization is cool with major multi-tenancy, I'd say that it's good enough for now. If it's dev-run, or if you want tenant scoping (e.g. one CF instance per business unit, or other isolated kind of microservices) I would absolutely not recommend it.
They are working on more lightweight versions. CF is pretty "enterprise," with the good and the bad that entails.
