Function open_page 

pub fn open_page(
    engine: &Engine,
    plan: &ContainerPlan,
    address: &str,
) -> Result<bool, LaunchFailure>

Shows address in the sign-in window inside the container of plan, and answers whether it is up: false when the image has no sign-in window, which an image built before it existed does not.

Runs an engine command and waits for it, which takes as long as starting a program in the container and no longer: the window is left running on its own. So it belongs on a background thread.

Errors

The engine’s own words when the container is not there any more or refuses.