Supply compose file context to callbacks

[LtChae]

Currently, Divo supports callbacks during the setup block that allow for code to be executed between the environment starting and the app's individual applications starting up.

https://github.com/UrbanOS-Public/divo/blob/9fccc400dcc64142698061b3da2a67e7828829e3/lib/divo.ex#L30-L40

I would like to propose passing the compose file's context to each callback to allow them access to ports and volume mount points for setup calls.

  def start(opts \\ []) do
    auto_start = Keyword.get(opts, :auto_start, true)
    post_docker_run = Keyword.get(opts, :post_docker_run, [])


    Divo.Compose.run(opts)

    context = Helper.fetch_config()
    |> Helper.get_context()

    Enum.each(post_docker_run, fn callback -> callback(context) end)


    app = Mix.Project.config() |> Keyword.get(:app)
    if auto_start, do: Application.ensure_all_started(app)
  end

[jdenen]

I'd suggest checking arity and passing the context based on that, so you don't break backwards compatibility. Also, it's just generally more flexible, which is always a win for a library IMO.

Enum.each(post_docker_run, fn
  callback when is_function(callback, 1) -> callback.(context)
  callback when is_function(callback, 0) -> callback.()
end)

[LtChae]

Good call, thanks!

We ran into a need for this when cleaning and populating Minio's fake S3 buckets prior to a test. We're doing it with a slightly hacky init container and a shell script, and this seemed like a possible solution to keeping test setup in the tests themselves.