Is it possible to deploy a container to Fly Machine which has two processes running - a golang service, as well as a docker daemon running in the background? The go service wraps the Docker Client, so it needs the go daemon running in the background.
Yes. Several ways. See here: Running Multiple Processes Inside A Fly.io App · Fly Docs
We also natively support multiple processes in a machine, see this post for details. I don’t believe it’s currently configurable via fly.toml so you’d need to be using the API directly.