[nickjj]

> Are you asking if you can run Docker inside a VM, and parcel that single VM out that way? You've got root in a full-fledged Linux VM, so you can do that.

On a single server VPS I'd use Docker Compose and up the project to run multiple containers.

On a multi-server set up I'd use Kubernetes and set up a deployment for each long running container.

On Heroku I'd use a Procfile to spin up web / workers as needed.

The Fly docs say if you have 1 Docker image you need to run an init system in the Docker image and manage that in your image, it also suggests not using 2 processes in 1 VM and recommends spinning up 1 VM per process.

I suppose I was looking for an easy solution to run multiple processes in 1 VM (in this case multiple Docker containers). The other 3 solutions are IMO easy because once you learn how they work you depend on the happy path of those tools using the built in mechanisms they support. In the Fly case, not even the docs cover how to do it other than rolling your own init system in Docker.

If you have root, can I run docker-compose up in a Fly VM? Will it respect things like graceful timeouts out of the box? Does it support everything Docker Compose supports in the context of that single VM?

[mrkurt]

This is embarrassingly non obvious in the docs, but you can run workers/web just like you would on Heroku: https://community.fly.io/t/preview-multi-process-apps-get-yo...

Most people run workers in their primary region with the writable DB, then distribute their web/DB read replicas.

[tptacek]

The document you cited (I wrote it!) is entirely about the different ways to run multiple processes in 1 VM.

There's no reason I can see why you couldn't run a VM that itself ran Docker, and have docker-compose run at startup. I wouldn't recommend it? It's kind of a lot of mechanism for a simple problem. I'd just use a process supervisor instead. But you could do it, and maybe I'm wrong and docker-compose is good for this.

What you can't do is use docker-compose to boot up a bunch of different containers in different VMs on Fly.io.

[nicoburns]

I think docker-compose is pretty good at this. One advantage is that you get a development environment and a production setup in a singe config file.

I feel like this setup might make quite a lot of sense if you have a bunch of micro services that are small enough that they can share resources.