Merge pull request #6 from spandex-project/inject_context

Add inject_context

Author: GregMefford

CHANGELOG.md

@@ -5,7 +5,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
-- No unreleased changes currently.
+
+[NEXT]: https://github.com/spandex-project/spandex_datadog/compare/vNEXT...v0.2.0
+
+### Added
+- `SpandexDatadog.Adapter.inject_context/3` added to support the new version of
+  the `Spandex.Adapter` behaviour.
 
 ## [0.2.0]
 

lib/spandex_datadog/adapter.ex

@@ -1,12 +1,16 @@
 defmodule SpandexDatadog.Adapter do
   @moduledoc """
-  A datadog APM implementation for spandex.
+  A Datadog APM implementation for Spandex.
   """
 
   @behaviour Spandex.Adapter
 
   require Logger
-  alias Spandex.SpanContext
+
+  alias Spandex.{
+    SpanContext,
+    Tracer
+  }
 
   @max_id 9_223_372_036_854_775_807
 
@@ -26,11 +30,10 @@ defmodule SpandexDatadog.Adapter do
   end
 
   @doc """
-  Fetches the datadog trace & parent IDs from the conn request headers
-  if they are present.
+  Fetches the Datadog-specific conn request headers if they are present.
   """
   @impl Spandex.Adapter
-  @spec distributed_context(conn :: Plug.Conn.t(), Keyword.t()) ::
+  @spec distributed_context(conn :: Plug.Conn.t(), Tracer.opts()) ::
           {:ok, SpanContext.t()}
           | {:error, :no_distributed_trace}
   def distributed_context(%Plug.Conn{} = conn, _opts) do
@@ -45,6 +48,26 @@ defmodule SpandexDatadog.Adapter do
     end
   end
 
+  @doc """
+  Injects Datadog-specific HTTP headers to represent the specified SpanContext
+  """
+  @impl Spandex.Adapter
+  @spec inject_context([{term(), term()}], SpanContext.t(), Tracer.opts()) :: [{term(), term()}]
+  def inject_context(headers, %SpanContext{} = span_context, _opts) when is_list(headers) do
+    span_context
+    |> tracing_headers()
+    |> Kernel.++(headers)
+  end
+
+  def inject_context(headers, %SpanContext{} = span_context, _opts) when is_map(headers) do
+    span_context
+    |> tracing_headers()
+    |> Enum.into(%{})
+    |> Map.merge(headers)
+  end
+
+  # Private Helpers
+
   @spec get_first_header(Plug.Conn.t(), String.t()) :: integer() | nil
   defp get_first_header(conn, header_name) do
     conn
@@ -61,4 +84,12 @@ defmodule SpandexDatadog.Adapter do
   end
 
   defp parse_header(_header), do: nil
+
+  defp tracing_headers(%SpanContext{trace_id: trace_id, parent_id: parent_id, priority: priority}) do
+    [
+      {"x-datadog-trace-id", to_string(trace_id)},
+      {"x-datadog-parent-id", to_string(parent_id)},
+      {"x-datadog-sampling-priority", to_string(priority)}
+    ]
+  end
 end

mix.exs

@@ -41,7 +41,7 @@ defmodule SpandexDatadog.MixProject do
   defp deps do
     [
       {:ex_doc, ">= 0.0.0", only: :dev},
-      {:spandex, "~> 2.2"},
+      {:spandex, "~> 2.3"},
       {:httpoison, "~> 0.13", only: :test},
       {:msgpax, "~> 1.1"}
     ]

mix.lock

@@ -1,21 +1,21 @@
 %{
-  "certifi": {:hex, :certifi, "2.3.1", "d0f424232390bf47d82da8478022301c561cf6445b5b5fb6a84d49a9e76d2639", [:rebar3], [{:parse_trans, "3.2.0", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
+  "certifi": {:hex, :certifi, "2.4.2", "75424ff0f3baaccfd34b1214184b6ef616d89e420b258bb0a5ea7d7bc628f7f0", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
   "earmark": {:hex, :earmark, "1.2.6", "b6da42b3831458d3ecc57314dff3051b080b9b2be88c2e5aa41cd642a5b044ed", [:mix], [], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.19.1", "519bb9c19526ca51d326c060cb1778d4a9056b190086a8c6c115828eaccea6cf", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.7", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
-  "hackney": {:hex, :hackney, "1.13.0", "24edc8cd2b28e1c652593833862435c80661834f6c9344e84b6a2255e7aeef03", [:rebar3], [{:certifi, "2.3.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "5.1.2", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.1", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
+  "hackney": {:hex, :hackney, "1.14.0", "66e29e78feba52176c3a4213d42b29bdc4baff93a18cfe480f73b04677139dee", [:rebar3], [{:certifi, "2.4.2", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.4", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
   "httpoison": {:hex, :httpoison, "0.13.0", "bfaf44d9f133a6599886720f3937a7699466d23bb0cd7a88b6ba011f53c6f562", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
-  "idna": {:hex, :idna, "5.1.2", "e21cb58a09f0228a9e0b95eaa1217f1bcfc31a1aaa6e1fdf2f53a33f7dbd9494", [:rebar3], [{:unicode_util_compat, "0.3.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup": {:hex, :makeup, "0.5.1", "966c5c2296da272d42f1de178c1d135e432662eca795d6dc12e5e8787514edf7", [:mix], [{:nimble_parsec, "~> 0.2.2", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.8.0", "1204a2f5b4f181775a0e456154830524cf2207cf4f9112215c05e0b76e4eca8b", [:mix], [{:makeup, "~> 0.5.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 0.2.2", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
+  "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
+  "makeup": {:hex, :makeup, "0.5.5", "9e08dfc45280c5684d771ad58159f718a7b5788596099bdfb0284597d368a882", [:mix], [{:nimble_parsec, "~> 0.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
+  "makeup_elixir": {:hex, :makeup_elixir, "0.8.2", "ecc130aaf3645d142f50ccd4c727f714afdb490062dcaf009f4c2d86332d1beb", [:mix], [{:makeup, "~> 0.5.5", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm"},
   "mime": {:hex, :mime, "1.3.0", "5e8d45a39e95c650900d03f897fbf99ae04f60ab1daa4a34c7a20a5151b7a5fe", [:mix], [], "hexpm"},
   "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm"},
   "msgpax": {:hex, :msgpax, "1.1.0", "e31625e256db2decca1ae2b841f21b4d2483b1332649ce3ebc96c7ff7a4986e3", [:mix], [{:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm"},
-  "nimble_parsec": {:hex, :nimble_parsec, "0.2.2", "d526b23bdceb04c7ad15b33c57c4526bf5f50aaa70c7c141b4b4624555c68259", [:mix], [], "hexpm"},
+  "nimble_parsec": {:hex, :nimble_parsec, "0.4.0", "ee261bb53214943679422be70f1658fff573c5d0b0a1ecd0f18738944f818efe", [:mix], [], "hexpm"},
   "optimal": {:hex, :optimal, "0.3.6", "46bbf52fbbbd238cda81e02560caa84f93a53c75620f1fe19e81e4ae7b07d1dd", [:mix], [], "hexpm"},
-  "parse_trans": {:hex, :parse_trans, "3.2.0", "2adfa4daf80c14dc36f522cf190eb5c4ee3e28008fc6394397c16f62a26258c2", [:rebar3], [], "hexpm"},
-  "plug": {:hex, :plug, "1.6.2", "e06a7bd2bb6de5145da0dd950070110dce88045351224bd98e84edfdaaf5ffee", [:mix], [{:cowboy, "~> 1.0.1 or ~> 1.1 or ~> 2.4", [hex: :cowboy, repo: "hexpm", optional: true]}, {:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}], "hexpm"},
-  "spandex": {:hex, :spandex, "2.2.0", "0d60e2a232074ebf6e299edcd3ee540df87541246ba5f5bd84c68a9bb00171bc", [:mix], [{:optimal, "~> 0.3.3", [hex: :optimal, repo: "hexpm", optional: false]}, {:plug, ">= 1.0.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
-  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.1", "28a4d65b7f59893bc2c7de786dec1e1555bd742d336043fe644ae956c3497fbe", [:make, :rebar], [], "hexpm"},
-  "unicode_util_compat": {:hex, :unicode_util_compat, "0.3.1", "a1f612a7b512638634a603c8f401892afbf99b8ce93a45041f8aaca99cadb85e", [:rebar3], [], "hexpm"},
+  "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm"},
+  "plug": {:hex, :plug, "1.6.3", "43088304337b9e8b8bd22a0383ca2f633519697e4c11889285538148f42cbc5e", [:mix], [{:cowboy, "~> 1.0.1 or ~> 1.1 or ~> 2.4", [hex: :cowboy, repo: "hexpm", optional: true]}, {:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}], "hexpm"},
+  "spandex": {:hex, :spandex, "2.3.0", "fcf214e57b601456369e9028482ccdb7c64ee1ed84cf89d5cc63fd83d46f2dec", [:mix], [{:optimal, "~> 0.3.3", [hex: :optimal, repo: "hexpm", optional: false]}, {:plug, ">= 1.0.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
+  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.4", "f0eafff810d2041e93f915ef59899c923f4568f4585904d010387ed74988e77b", [:make, :mix, :rebar3], [], "hexpm"},
+  "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm"},
 }

test/support/adapter_test.exs

@@ -105,4 +105,36 @@ defmodule Spandex.Test.Datadog.AdapterTest do
       assert {:error, :no_distributed_trace} = Adapter.distributed_context(conn, [])
     end
   end
+
+  describe "inject_context/3" do
+    test "Prepends distributed tracing headers to an existing list of headers" do
+      span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10}
+      headers = [{"header1", "value1"}, {"header2", "value2"}]
+
+      result = Adapter.inject_context(headers, span_context, [])
+
+      assert result == [
+               {"x-datadog-trace-id", "123"},
+               {"x-datadog-parent-id", "456"},
+               {"x-datadog-sampling-priority", "10"},
+               {"header1", "value1"},
+               {"header2", "value2"}
+             ]
+    end
+
+    test "Merges distributed tracing headers with an existing map of headers" do
+      span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10}
+      headers = %{"header1" => "value1", "header2" => "value2"}
+
+      result = Adapter.inject_context(headers, span_context, [])
+
+      assert result == %{
+               "x-datadog-trace-id" => "123",
+               "x-datadog-parent-id" => "456",
+               "x-datadog-sampling-priority" => "10",
+               "header1" => "value1",
+               "header2" => "value2"
+             }
+    end
+  end
 end

test/support/api_server_test.exs

@@ -29,7 +29,7 @@ defmodule SpandexDatadog.ApiServerTest do
     trace_id = 4_743_028_846_331_200_905
 
     {:ok, span_1} =
-      Spandex.Span.new(
+      Span.new(
         id: 4_743_028_846_331_200_906,
         start: 1_527_752_052_216_478_000,
         service: :foo,
@@ -40,7 +40,7 @@ defmodule SpandexDatadog.ApiServerTest do
       )
 
     {:ok, span_2} =
-      Spandex.Span.new(
+      Span.new(
         id: 4_743_029_846_331_200_906,
         start: 1_527_752_052_216_578_001,
         completion_time: 1_527_752_052_316_578_001,

test/support/datadog_test_api_server.ex

@@ -3,7 +3,7 @@ defmodule Spandex.Test.DatadogTestApiServer do
   Simply sends the data that would have been sent to datadog to self() as a message
   so that the test can assert on payloads that would have been sent to datadog
   """
-  def send_trace(trace, opts \\ []) do
+  def send_trace(trace, _opts \\ []) do
     formatted = SpandexDatadog.ApiServer.format(trace)
     send(self(), {:sent_datadog_spans, formatted})
   end