From f2b55f6eeac16d7d78f1e9aa0c33aa80b30d947f Mon Sep 17 00:00:00 2001
From: Dallin Crane <10406163+dallincrane@users.noreply.github.com>
Date: Wed, 10 Mar 2021 11:57:32 -0700
Subject: [PATCH 1/3] add container id to ApiServer.State and send in header

---
 lib/spandex_datadog/api_server.ex | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index 47694c4..dc223ba 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -26,7 +26,8 @@ defmodule SpandexDatadog.ApiServer do
       :waiting_traces,
       :batch_size,
       :sync_threshold,
-      :agent_pid
+      :agent_pid,
+      :container_id
     ]
   end
 
@@ -95,12 +96,28 @@ defmodule SpandexDatadog.ApiServer do
       waiting_traces: [],
       batch_size: opts[:batch_size],
       sync_threshold: opts[:sync_threshold],
-      agent_pid: agent_pid
+      agent_pid: agent_pid,
+      container_id: get_container_id()
     }
 
     {:ok, state}
   end
 
+  @cgroup_uuid "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
+  @cgroup_ctnr "[0-9a-f]{64}"
+  @cgroup_task "[0-9a-f]{32}-\\d+"
+  @cgroup_regex Regex.compile!("/(#{@cgroup_uuid}|#{@cgroup_ctnr}|#{@cgroup_task})(?:.scope)?$", "m")
+
+  defp get_container_id() do
+    with {:ok, file_binary} <- File.read("/proc/self/cgroup"),
+         true <- String.valid?(file_binary),
+         [_, container_id] <- Regex.run(@cgroup_regex, file_binary) do
+      container_id
+    else
+      _ -> nil
+    end
+  end
+
   @doc """
   Send spans asynchronously to DataDog.
   """
@@ -133,8 +150,9 @@ defmodule SpandexDatadog.ApiServer do
   end
 
   @spec send_and_log([Trace.t()], State.t()) :: :ok
-  def send_and_log(traces, %{verbose?: verbose?} = state) do
+  def send_and_log(traces, %{container_id: container_id, verbose?: verbose?} = state) do
     headers = @headers ++ [{"X-Datadog-Trace-Count", length(traces)}]
+    headers = headers ++ List.wrap(if container_id, do: {"Datadog-Container-ID", container_id})
 
     response =
       traces

From bfb3ba279396931fc6306ad9499ea4231315160b Mon Sep 17 00:00:00 2001
From: Dallin Crane <10406163+dallincrane@users.noreply.github.com>
Date: Wed, 14 Apr 2021 11:28:09 -0700
Subject: [PATCH 2/3] remove valid string check

---
 lib/spandex_datadog/api_server.ex | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index dc223ba..a66a95e 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -110,7 +110,6 @@ defmodule SpandexDatadog.ApiServer do
 
   defp get_container_id() do
     with {:ok, file_binary} <- File.read("/proc/self/cgroup"),
-         true <- String.valid?(file_binary),
          [_, container_id] <- Regex.run(@cgroup_regex, file_binary) do
       container_id
     else

From b80a876b63d0a3557e5fbfc8f4219de5e6504888 Mon Sep 17 00:00:00 2001
From: Dallin Crane <10406163+dallincrane@users.noreply.github.com>
Date: Tue, 4 May 2021 10:45:55 -0600
Subject: [PATCH 3/3] update regex

---
 lib/spandex_datadog/api_server.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index a66a95e..0beca52 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -106,7 +106,7 @@ defmodule SpandexDatadog.ApiServer do
   @cgroup_uuid "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
   @cgroup_ctnr "[0-9a-f]{64}"
   @cgroup_task "[0-9a-f]{32}-\\d+"
-  @cgroup_regex Regex.compile!("/(#{@cgroup_uuid}|#{@cgroup_ctnr}|#{@cgroup_task})(?:.scope)?$", "m")
+  @cgroup_regex Regex.compile!(".*(#{@cgroup_uuid}|#{@cgroup_ctnr}|#{@cgroup_task})(?:\\.scope)?$", "m")
 
   defp get_container_id() do
     with {:ok, file_binary} <- File.read("/proc/self/cgroup"),