Accepting function as key configuration

[michelboaventura]

Hey,

I'm using cloak/cloak_ecto and everything works great, thanks for the excellent project!

I'm thinking about accepting a function as value for the key configuration, so that it's easier to use env vars as keys without having to implement the init callback on Vault.

It'd be something like:

config :my_app, MyApp.Vault,
  ciphers: [
    default: {
      Cloak.Ciphers.AES.GCM,
      tag: "AES.GCM.V1", key: fn -> Base.decode64!(System.get_env("SOME_ENV")) end, iv_length: 12
    }
  ]

What do you think? I'm willing to create a PR if you think it's a good idea.

[michelboaventura]

Hey,

I've find out we can't use functions within release config files, so this wouldn't work. Sorry about that!