Add :request_headers warning to Config.initialize()

lib/appsignal/config.ex

@@ -19,6 +19,12 @@ defmodule Appsignal.Config do
     log: "file"
   }
 
+  @suggested_request_headers [
+    ~w(accept accept-charset accept-encoding accept-language cache-control),
+    ~w(connection content-length path-info range referer request-method),
+    ~w(request-uri server-name server-port server-protocol user-agent)
+  ]
+
   @doc """
   Initializes the AppSignal config. Looks at the config default, the
   Elixir-provided configuration and the various `APPSIGNAL_*`
@@ -36,13 +42,32 @@ defmodule Appsignal.Config do
       |> Map.merge(app_config)
       |> Map.merge(env_config)
 
+
     # Config is valid when we have a push api key
     config =
       config
       |> Map.put(:valid, !empty?(config[:push_api_key]))
 
     Application.put_env(:appsignal, :config, config)
 
+    if config[:valid] && !config[:request_headers] && !test?() do
+      require Logger
+
+      Logger.warn("""
+      The :request_headers config was not set in the AppSignal configuration, falling back to the default list. Please explicitly list response headers to send to AppSignal in config/appsignal.exs:
+
+        request_headers: ~w(
+      #{multiline_suggested_request_headers()}
+        )
+
+      Or set the APPSIGNAL_REQUEST_HEADERS environment variable:
+
+        $ export APPSIGNAL_REQUEST_HEADERS="#{single_line_suggested_request_headers()}"
+
+      Please check https://github.com/appsignal/appsignal-elixir/pull/336 for more information on this change.
+      """)
+    end
+
     case config[:valid] do
       true ->
         :ok
@@ -232,6 +257,24 @@ defmodule Appsignal.Config do
     |> Enum.into(%{})
   end
 
+  def single_line_suggested_request_headers do
+    @suggested_request_headers
+    |> List.flatten
+    |> Enum.join(",")
+  end
+
+  def multiline_suggested_request_headers do
+    Enum.map_join(@suggested_request_headers, "\n", fn(row) ->
+      "    #{Enum.join(row, " ")}"
+    end)
+  end
+
+  defp test? do
+    Mix.env
+    |> Atom.to_string()
+    |> String.starts_with?("test")
+  end
+
   # When you use Appsignal.Config you get a handy config macro which
   # can be used to read the application config.
   defmacro __using__(_) do

lib/mix/tasks/appsignal.install.ex

@@ -1,15 +1,9 @@
 defmodule Mix.Tasks.Appsignal.Install do
   use Mix.Task
-  alias Appsignal.Utils.PushApiKeyValidator
+  alias Appsignal.{Utils.PushApiKeyValidator, Config}
 
   @demo Application.get_env(:appsignal, :appsignal_demo, Appsignal.Demo)
 
-  @request_headers [
-    ~w(accept accept-charset accept-encoding accept-language cache-control),
-    ~w(connection content-length path-info range referer request-method),
-    ~w(request-uri server-name server-port server-protocol user-agent)
-  ]
-
   def run([]) do
     header()
     IO.puts "We're missing an AppSignal Push API key and cannot continue."
@@ -22,7 +16,7 @@ defmodule Mix.Tasks.Appsignal.Install do
   def run([push_api_key]) do
     config = %{active: true, push_api_key: push_api_key}
     Application.put_env(:appsignal, :config, config)
-    Appsignal.Config.initialize
+    Config.initialize
 
     header()
     validate_push_api_key()
@@ -103,7 +97,7 @@ defmodule Mix.Tasks.Appsignal.Install do
     IO.puts ~s(  export APPSIGNAL_APP_NAME="#{config[:name]}")
     IO.puts ~s(  export APPSIGNAL_APP_ENV="production")
     IO.puts ~s(  export APPSIGNAL_PUSH_API_KEY="#{config[:push_api_key]}")
-    IO.puts ~s(  export APPSIGNAL_REQUEST_HEADERS="#{single_line_request_headers()}")
+    IO.puts ~s(  export APPSIGNAL_REQUEST_HEADERS="#{Config.single_line_suggested_request_headers()}")
   end
 
   defp write_config_file(config) do
@@ -159,25 +153,13 @@ defmodule Mix.Tasks.Appsignal.Install do
     end
   end
 
-  defp single_line_request_headers do
-    @request_headers
-    |> List.flatten
-    |> Enum.join(",")
-  end
-
-  defp multiline_request_headers do
-    Enum.map_join(@request_headers, "\n", fn(row) ->
-      "    #{Enum.join(row, " ")}"
-    end)
-  end
-
   # Contents for the config/appsignal.exs file.
   defp appsignal_config_file_contents(config) do
     options = [
       ~s(  name: "#{config[:name]}",),
       ~s(  push_api_key: "#{config[:push_api_key]}",),
       ~s{  request_headers: ~w(},
-      multiline_request_headers(),
+      Config.multiline_suggested_request_headers(),
       ~s{  ),},
       ~s(  env: Mix.env)
     ]