In Docker Desktop, when you start a container with a not-yet-initialized volume, Docker automatically initializes that volume with the files that are in the container image at the directory path where the volume will be mounted.
Fly.io doesn’t do that, requiring the container’s entrypoint to perform such initialization.
Since Fly.io generally tries to create a UX that’s familiar to people who already know Docker, it would be great if Fly.io matched Docker’s behavior by also automatically initializing the volume like Docker does.