Merge pull request #4 from GameAnalytics/daemon-config-env-vars

Get X-Ray daemon address and port from environment variables

Author: legoscia

lib/aws_ex_ray.ex

@@ -410,8 +410,8 @@ defmodule AwsExRay do
     name        :: String.t,
     annotations :: map,
     opts        :: keyword,
-    func        :: fun
-  ) :: :ok
+    func        :: (String.t -> ret)
+  ) :: ret when ret: term
   def subsegment(name, annotations, opts, func) do
 
     subsegment_state = start_subsegment(name, opts)

lib/aws_ex_ray/aws_metadata.ex

@@ -22,14 +22,18 @@ defmodule AwsExRay.AwsMetadata do
     case result do
       %{"ec2" => _} ->
         Application.put_env(:aws_ex_ray, :aws_metadata, result)
+      {{%RuntimeError{message: error_message = "Instance Meta Error" <> _}, _}, _} ->
+        # Failed to reach the instance metadata endpoint.
+        # Most likely we're not running on an EC2 instance.
+        :ok
       _ ->
         Logger.debug("Error during instance identity request: #{Exception.format_exit(result)}")
     end
     {:stop, :normal, state}
   end
 
   def request_aws_metadata() do
-    config = ExAws.Config.new(:ec2, require_imds_v2: true)
+    config = ExAws.Config.new(:ec2, require_imds_v2: true, access_key_id: "", secret_access_key: "", security_token: "")
     result = ExAws.InstanceMeta.request(config, "http://169.254.169.254/latest/dynamic/instance-identity/document")
     map = Jason.decode!(result)
     :erlang.exit(%{"ec2" => %{

lib/aws_ex_ray/config.ex

@@ -56,7 +56,8 @@ defmodule AwsExRay.Config do
   def daemon_address() do
 
     address = get(:daemon_address,
-                  @default_daemon_address)
+      System.get_env("_AWS_XRAY_DAEMON_ADDRESS",
+        @default_daemon_address))
 
     charlist_address = address |> String.to_charlist()
 
@@ -74,8 +75,17 @@ defmodule AwsExRay.Config do
 
   @spec daemon_port() :: non_neg_integer
   def daemon_port() do
-    get(:daemon_port,
-        @default_daemon_port)
+    case get(:daemon_port, nil) do
+      nil ->
+        case System.get_env("_AWS_XRAY_DAEMON_PORT") do
+          port when is_binary(port) ->
+            String.to_integer(port)
+          nil ->
+            @default_daemon_port
+        end
+      port ->
+        port
+    end
   end
 
   @spec default_annotation() :: map