You're right, they should make that much more clear. I'd expect it to be on the left side menu, just like they have all the "Run a [language] app".

Based on your first link [0], I saw,

> You can run most applications with a Dockerfile using the flyctl command.

With that, I looked over the left-side menu, and clicked `flyctl`[1], since it seems that's what you'd need to use to deploy an existing app with Docker. After that, I clicked on "Launch an App" [2], which shows help for the `flyctl launch` subcommand, including a parameter `--dockerfile`. I think that's how you would deploy an existing app with docker?

[0] https://fly.io/docs/introduction/ [1] https://fly.io/docs/flyctl/ [2] https://fly.io/docs/flyctl/launch/