Reconfigure plug at runtime with env

Closes #1165

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/web/plug_configs.ex

@@ -0,0 +1,14 @@
+defmodule Mobilizon.Web.PlugConfigs do
+  @moduledoc """
+  Runtime configuration for plugs
+  """
+
+  def parsers do
+    upload_limit =
+      Keyword.get(Application.get_env(:mobilizon, :instance, []), :upload_limit, 10_485_760)
+
+    [
+      parsers: [:urlencoded, {:multipart, length: upload_limit}, :json, Absinthe.Plug.Parser]
+    ]
+  end
+end