I believe you cannot pass options directly to individual plugs at runtime, as this behavior is by design. Plug pipelines and their constituent plugs are defined and configured at compile time.

I’m not entirely sure what you’re trying to achieve, but if your goal is to test behavior, you should consider testing each plug individually.

If you really need to pass runtime data to individual plugs in a pipeline, you might consider using conn.assigns for that purpose. Here’s an example:

defmodule PlugPipeline do
  use Plug.Builder

  plug(:my_plug)

  def my_plug(conn, _opts) do
    10 = Keyword.get(conn.assigns.opts, :my_plug_option)
    conn
  end

  def call(conn, opts) do
    conn |> Plug.Conn.assign(:opts, opts) |> super(opts)
  end
end