Phoenix endpoint config {:system, "ENV"} question.

soloradish · March 21, 2019, 3:19am

Hi there,

I knew I can get runtime env use {:system, “ENV”} setting format. I have a question after I read the endpoint’s source code.

github.com

phoenixframework/phoenix/blob/f1f52836d6cc84b8039d10b7a00818950f51b0ea/lib/phoenix/endpoint/supervisor.ex#L359


end


defp raise_invalid_path(path) do
  raise ArgumentError, "expected a path starting with a single / but got #{inspect path}"
end


# TODO: Deprecate {:system, env_var} once we require Elixir v1.7+
defp host_to_binary({:system, env_var}), do: host_to_binary(System.get_env(env_var))
defp host_to_binary(host), do: host


# TODO: Deprecate {:system, env_var} once we require Elixir v1.7+
defp port_to_integer({:system, env_var}), do: port_to_integer(System.get_env(env_var))
defp port_to_integer(port) when is_binary(port), do: String.to_integer(port)
defp port_to_integer(port) when is_integer(port), do: port


def pubsub_server(endpoint) do
  {:cache, endpoint.config(:pubsub)[:name]}
end


@doc """
Invoked to warm up caches on start and config change.

As this line said, the {:system, “ENV”} format will deprecate after elixir 1.7+. I want to know what change in Elixir 1.7+ made this happen?

Thanks.

NobbZ · March 21, 2019, 6:08am

I think this is an arbitrary choice. I’m not aware of any technical reasons that might be a cause for this deprecation, except for the fact that distillery 2.0 and therefore config providers are available for Elixir >= 1.6.

:system tuples in all of their variations have always been a hack rather than a cure.

josevalim · March 21, 2019, 1:05pm

You are correct. I added those notes a long time ago, thinking that a solution would arrive to Elixir earlier (this was added probably around the time the first proposals regarding config were made to the forum) but Elixir v1.9 will make the config providers approach official, so we will likely deprecate it when Elixir 1.11 or 1.12 is out.