413 Request Entity Too Large Elixir Plug

Question

I am sending am sending an image in the base64 form, then creating an image with it and sending it to AWS.

At first, I thought it was a Nginx issue. So I changed client_max_body_size to a max value, But it didn't work. I am still getting 413 Request Entity Too Large error.

It's only happening when I am sending a high-resolution image's Base64 string. As we are using a Plug to authenticate requests. I just found out about Plug Parser Behaviour. The Plug I have created is:

defmodule EvercamMediaWeb.AuthenticationPlug do
  import Plug.Conn

  def init(_opts) do
  end

  def call(conn, _) do
    api_id = extract_credential(conn, %{header: "x-api-id", query: "api_id"})
    api_key = extract_credential(conn, %{header: "x-api-key", query: "api_key"})
    token =
      conn
      |> extract_credential(%{header: "authorization", query: "authorization"})
      |> String.downcase
      |> String.replace_leading("bearer ", "")

    case EvercamMediaWeb.Auth.validate(api_id, api_key, token) do
      :valid ->
        conn
      {:valid, user} ->
        conn
        |> assign(:current_user, user)
      :invalid ->
        conn
        |> put_resp_content_type("application/json")
        |> resp(401, Poison.encode!(%{message: "Invalid API keys"}))
        |> send_resp
        |> halt
    end
  end

  defp extract_credential(conn, %{header: header_name, query: query_string_name}) do
    extract_credential_from_query_string(conn, query_string_name) || extract_credential_from_header(conn, header_name)
  end

  defp extract_credential_from_query_string(conn, query_string_name) do
    Map.get(conn.params, query_string_name)
  end

  defp extract_credential_from_header(conn, header_name) do
    conn
    |> Plug.Conn.get_req_header(header_name)
    |> List.first
    |> to_string
  end
end

How I can modify plug's behaviour to use :query_string_length &

 {:multipart, length: 20_000_000} # Increase to 20MB max upload

in the above Plug, So it may support for max size of string and also Upload to the max as well.

thanks in advance.

Aleksei Matiushkin Aleksei Matiushkin · Accepted Answer · 2018-03-12T07:46:58

In your MyAppWeb.Endpoint file you should have something like this to configure the parser:

plug Plug.Parsers,
  parsers: [:urlencoded, :multipart, :json],
  pass: ["*/*"],
  json_decoder: Poison

Change parsers to:

  parsers: [:urlencoded, 
           {:multipart, length: 20_000_000},
            :json]
  query_string_length: 1_000_000,

413 Request Entity Too Large Elixir Plug

1 Answers