web: do not error when proxy is unreachable

lib/ha_handler/ha_proxy.ex

@@ -74,7 +74,19 @@ defmodule HAHandler.HAProxy do
   Executes and parse the output of the `show stats` HAProxy command, returning
   a list of Maps.
   """
-  def get_stats() do
+  def get_stats(opts \\ [])
+  def get_stats([hide_error: true]) do
+    case get_stats() do
+      {:error, _err} ->
+        %{
+          "Frontend" => %{},
+          "Backend" => %{},
+          "Server" => %{}
+        }
+      stats -> stats
+    end
+  end
+  def get_stats(_opts) do
     case execute("show stat json") do
       {:ok, raw} ->
         case Poison.decode(raw) do

lib/ha_handler/web/controller.ex

@@ -19,10 +19,8 @@ defmodule HAHandler.Web.Controller do
 	def index(conn) do
 		{:ok, hostname} = :net_adm.dns_hostname(:net_adm.localhost)
 
-		stats = HAProxy.get_stats()
-
 		assigns = [
-			haproxy_stats: stats,
+			haproxy_stats: HAProxy.get_stats([hide_error: true]),
 			pgsql_status: PGSQL.status(),
 			hostname: hostname,
 			otp_app: HAHandler.otp_app(),