Logging errors from server when generating URL

[sigu]

The URL generation logic is inside the oidcc_plug and its called by the authorize callback defined in inside our controller as shown below

defmodule SampleAppWeb.OidccController do
  use SampleAppWeb, :controller

  plug Oidcc.Plug.Authorize .....

  plug Oidcc.Plug.AuthorizationCallback, .......

  @doc false
  def callback_uri, do: url(~p"/oidcc/callback")

  def authorize(conn, _params), do: conn

end

However if the server fails to generate a URL due to an error I only see an error Redirect URI Generation Failed without the error details on the IO.
If the error was generated on the callback callback then we can handle it as shown below

defmodule SampleAppWeb.OidccController do
  use SampleAppWeb, :controller

  plug Oidcc.Plug.Authorize .....

  plug Oidcc.Plug.AuthorizationCallback, .......

  @doc false
  def callback_uri, do: url(~p"/oidcc/callback")

  def authorize(conn, _params), do: conn

  def callback(%Plug.Conn{private: %{
    Oidcc.Plug.AuthorizationCallback => {:error, reason}
  }} = conn, _params) do
    conn
    |> put_status(400)
    |> render(:error, reason: reason)
  end
end

Here is the line that throws the error

oidcc_plug/lib/oidcc/plug/authorize.ex

Line 148 in d76a47d

raise Error, reason: reason

Question

How can I log the details of the error to my logger?

[maennchen]

The current solution stores the reason in the error struct, but does not add it to the error message.

The reason for this is that some errors contain confidential data like client secrets and they should not be logged directly.

We should however add some more details. We can for example add the first element of the error tuple to the error message. Based on your slack message, it would mention that there was an HTTP error behind the scenes.

Since I already have an issue open for revamping the error handling, I added this to the description. #26

To get all information out of the error, you should be able to implement a custom error view in phoenix, where you have access to the whole struct.

[sigu]

Awesome, thank you for having a look.