Fix bug where service response headers were not getting forwarded

lib/plug/forward_request.ex

@@ -10,6 +10,7 @@ defmodule Heimdall.Plug.ForwardRequest do
   """
 
   import Rackla
+  import Plug.Conn
 
   @doc """
   Init will reshape the data coming in from
@@ -35,13 +36,29 @@ defmodule Heimdall.Plug.ForwardRequest do
     base <> request_path <> query_string
   end
 
+  defp set_headers(conn, headers) do
+    Enum.reduce(headers, conn, fn({key, value}, conn) ->
+      put_resp_header(conn, key, value)
+    end)
+  end
+
   defp forward_conn(conn, forward_url) do
     {_, {:ok, forward_request}} = incoming_request_conn(conn)
     new_url = build_url(forward_url, conn)
-    forward_request
-    |> Map.put(:url, new_url)
-    |> request(follow_redirect: true, force_redirect: true)
-    |> response
+    rackla_response =
+      forward_request
+      |> Map.put(:url, new_url)
+      |> request(follow_redirect: true, force_redirect: true, full: true)
+      |> collect
+    case rackla_response do
+      %Rackla.Response{status: status, headers: headers, body: body} ->
+        conn
+        |> resp(status, body)
+        |> set_headers(headers)
+      other ->
+        conn
+        |> resp(500, "An error occured communicating with service, reason: #{inspect(other)}")
+    end
   end
 
   @doc """

mix.exs

@@ -4,7 +4,7 @@ defmodule Heimdall.Mixfile do
   def project do
     [
       app: :heimdall,
-      version: "0.2.2",
+      version: "0.2.3",
       elixir: "~> 1.3",
       build_embedded: Mix.env == :prod,
       start_permanent: Mix.env == :prod,

test/plug/forward_request_test.exs

@@ -3,6 +3,7 @@ defmodule Heimdall.Test.Plug.ForwardRequestTest do
   use Plug.Test
 
   import Plug.Test
+  import ExUnit.CaptureLog
 
   alias Heimdall.Plug.ForwardRequest
 
@@ -49,6 +50,32 @@ defmodule Heimdall.Test.Plug.ForwardRequestTest do
       assert conn.status == 200
       assert conn.resp_body == "forwarded"
     end
+
+    test "forwards headers from response" do
+      forward_url = %{"forward_url" => "http://localhost:8088"}
+      conn =
+        :get
+        |> conn("http://localhost/forward-test/headers")
+        |> ForwardRequest.call(ForwardRequest.init(forward_url))
+
+      assert conn.status == 200
+      assert conn.resp_body == "forwarded"
+      assert conn |> get_resp_header("x-test-forward") == ["forwarded"]
+    end
+
+    test "gives 500 if cannot connect to service" do
+      forward_url = %{"forward_url" => "http://localhost:50000"}
+
+      capture_log fn ->
+        conn =
+          :get
+          |> conn("http://localhost/forward-test")
+          |> ForwardRequest.call(ForwardRequest.init(forward_url))
+
+        assert conn.status == 500
+        assert conn.resp_body != "forwarded"
+      end
+    end
   end
 
   test "changing the path info changes the request path" do

test/test_router.ex

@@ -14,6 +14,12 @@ defmodule Heimdall.Test.TestRouter do
     |> resp(200, "forwarded")
   end
 
+  get "/forward-test/headers" do
+    conn
+    |> put_resp_header("x-test-forward", "forwarded")
+    |> resp(200, "forwarded")
+  end
+
   get "/test" do
     conn
     |> resp(200, "ok")