The Dragonfly.Backend using Fly.io machines.

The only required configuration is telling Dragonly to use the Dragonfly.FlyBackend by default and the :token which is your Fly.io API token. These can be set via application configuration in your config/runtime.exs withing a :prod block:

if config_env() == :prod do
  config :dragonfly, :backend, Dragonfly.FlyBackend
  config :dragonfly, Dragonfly.FlyBackend, token: System.fetch_env!("FLY_API_TOKEN")
  ...
end

To set your FLY_API_TOKEN secret, you can run the following commands locally:

$ fly secrets set FLY_API_TOKEN="$(fly auth token)"