From edb4f896729758ceb4d3cae92b6db5976045de9f Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 30 Jun 2025 14:13:39 -0700
Subject: [PATCH 01/17] Update docker container ID test to use a UUID that's 64
 hex-chars long, as this is what other tracers are testing

---
 test/test_platform_util.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/test/test_platform_util.cpp b/test/test_platform_util.cpp
index e333e04e..4693de56 100644
--- a/test/test_platform_util.cpp
+++ b/test/test_platform_util.cpp
@@ -19,8 +19,8 @@ PLATFORM_UTIL_TEST("find docker container ID") {
       {__LINE__, "empty inputs", "", nullopt},
       {__LINE__, "no docker container ID", "coucou", nullopt},
       {__LINE__, "one line with docker container ID",
-       "0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope",
-       "abcdef0123456789abcdef0123456789"},
+       "0::/system.slice/docker-cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411.scope",
+       "cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411"},
       {__LINE__, "multiline wihtout docker container ID", R"(
 0::/
 10:memory:/user.slice/user-0.slice/session-14.scope
@@ -41,7 +41,7 @@ PLATFORM_UTIL_TEST("find docker container ID") {
 9:hugetlb:/
 8:cpuset:/
 7:pids:/user.slice/user-0.slice/session-14.scope
-3:cpu:/system.slice/docker-abcdef0123456789abcdef0123456789.scope
+3:cpu:/system.slice/docker-cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411.scope
 6:freezer:/
 5:net_cls,net_prio:/
 4:perf_event:/
@@ -49,7 +49,7 @@ PLATFORM_UTIL_TEST("find docker container ID") {
 2:devices:/user.slice/user-0.slice/session-14.scope
 1:name=systemd:/user.slice/user-0.slice/session-14.scope
     )",
-       "abcdef0123456789abcdef0123456789"},
+       "cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411"},
   }));
 
   CAPTURE(test_case.name);

From bb3d458af70b672064cfcb7135d8885451172e02 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 30 Jun 2025 14:17:24 -0700
Subject: [PATCH 02/17] Rename container::find_docker_container_id to
 container::find_container_id and update its implementation so that it is
 regex-based and covers the same set of inputs as other tracers, like Java and
 .NET  -- the implementation is borrowed from the Java tracer

---
 src/datadog/platform_util.cpp | 30 +++++++++++++----------
 src/datadog/platform_util.h   |  8 +++----
 test/test_platform_util.cpp   | 45 ++++++++++++++++++++++++++++++++++-
 3 files changed, 65 insertions(+), 18 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 381a3aba..e9b62e1a 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -2,6 +2,8 @@
 
 #include <cstdint>
 #include <fstream>
+#include <cassert>
+#include <regex>
 
 // clang-format off
 #if defined(__x86_64__) || defined(_M_X64)
@@ -338,31 +340,33 @@ Optional<Cgroup> get_cgroup_version() {
   return nullopt;
 }
 
-Optional<std::string> find_docker_container_id_from_cgroup() {
+Optional<std::string> find_container_id_from_cgroup() {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
   if (!cgroup_fd.is_open()) return nullopt;
 
-  return find_docker_container_id(cgroup_fd);
+  return find_container_id(cgroup_fd);
 }
 #endif
 }  // namespace
 
-Optional<std::string> find_docker_container_id(std::istream& source) {
-  constexpr std::string_view docker_str = "docker-";
+Optional<std::string> find_container_id(std::istream& source) {
+  static const std::string uuid_regex_str = "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
+  static const std::string container_regex_str = "[0-9a-f]{64}";
+  static const std::string task_regex_str = "[0-9a-f]{32}-\\d+";
+  static const std::regex path_reg(
+      "(?:.+)?(" + uuid_regex_str + "|" + container_regex_str + "|" + task_regex_str +
+      ")(?:\\.scope)?$");
 
   std::string line;
   while (std::getline(source, line)) {
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
-    if (auto beg = line.find(docker_str); beg != std::string::npos) {
-      beg += docker_str.size();
-      auto end = line.find(".scope", beg);
-      if (end == std::string::npos || end - beg <= 0) {
-        continue;
-      }
+    std::smatch match;
+    if (std::regex_match(line, match, path_reg)) {
+      assert(match.ready());
+      assert(match.size() == 2);
 
-      auto container_id = line.substr(beg, end - beg);
-      return container_id;
+      return match.str(1);
     }
   }
 
@@ -382,7 +386,7 @@ Optional<ContainerID> get_id() {
   ContainerID id;
   switch (*maybe_cgroup) {
     case Cgroup::v1: {
-      if (auto maybe_id = find_docker_container_id_from_cgroup()) {
+      if (auto maybe_id = find_container_id_from_cgroup()) {
         id.value = *maybe_id;
         id.type = ContainerID::Type::container_id;
         break;
diff --git a/src/datadog/platform_util.h b/src/datadog/platform_util.h
index d7fd0c3b..a71d2df6 100644
--- a/src/datadog/platform_util.h
+++ b/src/datadog/platform_util.h
@@ -84,13 +84,13 @@ struct ContainerID final {
   std::string value;
 };
 
-/// Find the docker container ID from a given source.
+/// Find the container ID from a given source.
 /// This function is exposed mainly for testing purposes.
 ///
-/// @param source The input from which to read the Docker container ID.
-/// @return An Optional containing the Docker container ID if found, otherwise
+/// @param source The input from which to read the container ID.
+/// @return An Optional containing the container ID if found, otherwise
 /// nothing.
-Optional<std::string> find_docker_container_id(std::istream& source);
+Optional<std::string> find_container_id(std::istream& source);
 
 /// Function to retrieve the container metadata.
 ///
diff --git a/test/test_platform_util.cpp b/test/test_platform_util.cpp
index 4693de56..30d95e53 100644
--- a/test/test_platform_util.cpp
+++ b/test/test_platform_util.cpp
@@ -56,7 +56,50 @@ PLATFORM_UTIL_TEST("find docker container ID") {
 
   std::istringstream is(test_case.input);
 
-  auto maybe_container_id = container::find_docker_container_id(is);
+  auto maybe_container_id = container::find_container_id(is);
+  if (test_case.expected_container_id.has_value()) {
+    REQUIRE(maybe_container_id.has_value());
+    CHECK(*maybe_container_id == *test_case.expected_container_id);
+  } else {
+    CHECK(!maybe_container_id.has_value());
+  }
+}
+
+PLATFORM_UTIL_TEST("find Fargate 1.3 container ID") {
+  struct TestCase {
+    size_t line;
+    std::string_view name;
+    std::string input;
+    Optional<std::string> expected_container_id;
+  };
+
+  auto test_case = GENERATE(values<TestCase>({
+      {__LINE__, "empty inputs", "", nullopt},
+      {__LINE__, "no Fargate 1.3 container ID", "coucou", nullopt},
+      {__LINE__, "one line with Fargate 1.3 container ID",
+       "1:name=systemd:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da",
+       "432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da"},
+      {__LINE__, "multiline with Fargate 1.3 container ID", R"(
+11:hugetlb:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+10:pids:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+9:cpuset:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+8:net_cls,net_prio:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+7:cpu,cpuacct:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+6:perf_event:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+5:freezer:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+4:devices:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+3:blkio:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+2:memory:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+1:name=systemd:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
+    )",
+       "432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da"},
+  }));
+
+  CAPTURE(test_case.name);
+
+  std::istringstream is(test_case.input);
+
+  auto maybe_container_id = container::find_container_id(is);
   if (test_case.expected_container_id.has_value()) {
     REQUIRE(maybe_container_id.has_value());
     CHECK(*maybe_container_id == *test_case.expected_container_id);

From 2174c8089432e91db04232a10e8ccfb932ff2675 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 30 Jun 2025 14:25:46 -0700
Subject: [PATCH 03/17] Add other cgroup file examples from the .NET Tracer

---
 test/test_platform_util.cpp | 99 ++++++++++++++++++++++++++++++++++---
 1 file changed, 92 insertions(+), 7 deletions(-)

diff --git a/test/test_platform_util.cpp b/test/test_platform_util.cpp
index 30d95e53..caf2e03e 100644
--- a/test/test_platform_util.cpp
+++ b/test/test_platform_util.cpp
@@ -65,7 +65,7 @@ PLATFORM_UTIL_TEST("find docker container ID") {
   }
 }
 
-PLATFORM_UTIL_TEST("find Fargate 1.3 container ID") {
+PLATFORM_UTIL_TEST("find multiline container IDs") {
   struct TestCase {
     size_t line;
     std::string_view name;
@@ -74,12 +74,50 @@ PLATFORM_UTIL_TEST("find Fargate 1.3 container ID") {
   };
 
   auto test_case = GENERATE(values<TestCase>({
-      {__LINE__, "empty inputs", "", nullopt},
-      {__LINE__, "no Fargate 1.3 container ID", "coucou", nullopt},
-      {__LINE__, "one line with Fargate 1.3 container ID",
-       "1:name=systemd:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da",
-       "432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da"},
-      {__LINE__, "multiline with Fargate 1.3 container ID", R"(
+      {__LINE__, "Docker", R"(
+13:name=systemd:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+12:pids:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+11:hugetlb:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+10:net_prio:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+9:perf_event:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+8:net_cls:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+7:freezer:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+6:devices:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+5:memory:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+4:blkio:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+3:cpuacct:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+2:cpu:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+1:cpuset:/docker/3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860
+    )",
+       "3726184226f5d3147c25fdeab5b60097e378e8a720503a5e19ecfdf29f869860"},
+      {__LINE__, "Kubernetes", R"(
+11:perf_event:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+10:pids:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+9:memory:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+8:cpu,cpuacct:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+7:blkio:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+6:cpuset:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+5:devices:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+4:freezer:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+3:net_cls,net_prio:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+2:hugetlb:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+1:name=systemd:/kubepods/besteffort/pod3d274242-8ee0-11e9-a8a6-1e68d864ef1a/3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1
+1:name=systemd:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod2d3da189_6407_48e3_9ab6_78188d75e609.slice/docker-3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1.scope
+    )",
+       "3e74d3fd9db4c9dd921ae05c2502fb984d0cde1b36e581b13f79c639da4518a1"},
+      {__LINE__, "Ecs", R"(
+9:perf_event:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+8:memory:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+7:hugetlb:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+6:freezer:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+5:devices:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+4:cpuset:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+3:cpuacct:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+2:cpu:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+1:blkio:/ecs/haissam-ecs-classic/5a0d5ceddf6c44c1928d367a815d890f/38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce
+    )",
+       "38fac3e99302b3622be089dd41e7ccf38aff368a86cc339972075136ee2710ce"},
+      {__LINE__, "Fargate1Dot3", R"(
 11:hugetlb:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
 10:pids:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
 9:cpuset:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
@@ -93,6 +131,53 @@ PLATFORM_UTIL_TEST("find Fargate 1.3 container ID") {
 1:name=systemd:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
     )",
        "432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da"},
+      {__LINE__, "Fargate1Dot4", R"(
+11:hugetlb:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+10:pids:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+9:cpuset:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+8:net_cls,net_prio:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+7:cpu,cpuacct:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+6:perf_event:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+5:freezer:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+4:devices:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+3:blkio:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+2:memory:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+1:name=systemd:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890
+    )",
+       "34dc0b5e626f2c5c4c5170e34b10e765-1234567890"},
+      {__LINE__, "EksNodegroup", R"(
+11:blkio:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+10:cpuset:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+9:perf_event:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+8:memory:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+7:pids:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+6:cpu,cpuacct:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+5:net_cls,net_prio:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+4:devices:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+3:freezer:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+2:hugetlb:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+1:name=systemd:/kubepods.slice/kubepods-pod9508fe66_7675_4003_b7c9_d83e9f8f85e5.slice/cri-containerd-26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4.scope
+    )",
+       "26cfbe35e08b24f053011af4ada23d8fcbf81f27f8331a94f56de5b677c903e4"},
+      {__LINE__, "PcfContainer1", R"(
+12:memory:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+11:rdma:/
+10:freezer:/garden/6f265890-5165-7fab-6b52-18d1
+9:hugetlb:/garden/6f265890-5165-7fab-6b52-18d1
+8:pids:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+7:perf_event:/garden/6f265890-5165-7fab-6b52-18d1
+6:cpu,cpuacct:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+5:net_cls,net_prio:/garden/6f265890-5165-7fab-6b52-18d1
+4:cpuset:/garden/6f265890-5165-7fab-6b52-18d1
+3:blkio:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+2:devices:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+1:name=systemd:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+    )",
+       "6f265890-5165-7fab-6b52-18d1"},
+      {__LINE__, "PcfContainer2", R"(
+1:name=systemd:/system.slice/garden.service/garden/6f265890-5165-7fab-6b52-18d1
+    )",
+       "6f265890-5165-7fab-6b52-18d1"},
   }));
 
   CAPTURE(test_case.name);

From 136d4cc0a901ddfc5639db8a82d36875b1b057a9 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 30 Jun 2025 16:40:25 -0700
Subject: [PATCH 04/17] Fix formatting

---
 src/datadog/platform_util.cpp | 12 +++++++-----
 test/test_platform_util.cpp   |  4 +++-
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index e9b62e1a..00c50343 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -1,8 +1,8 @@
 #include "platform_util.h"
 
+#include <cassert>
 #include <cstdint>
 #include <fstream>
-#include <cassert>
 #include <regex>
 
 // clang-format off
@@ -350,12 +350,14 @@ Optional<std::string> find_container_id_from_cgroup() {
 }  // namespace
 
 Optional<std::string> find_container_id(std::istream& source) {
-  static const std::string uuid_regex_str = "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
+  static const std::string uuid_regex_str =
+      "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
+      "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
   static const std::string container_regex_str = "[0-9a-f]{64}";
   static const std::string task_regex_str = "[0-9a-f]{32}-\\d+";
-  static const std::regex path_reg(
-      "(?:.+)?(" + uuid_regex_str + "|" + container_regex_str + "|" + task_regex_str +
-      ")(?:\\.scope)?$");
+  static const std::regex path_reg("(?:.+)?(" + uuid_regex_str + "|" +
+                                   container_regex_str + "|" + task_regex_str +
+                                   ")(?:\\.scope)?$");
 
   std::string line;
   while (std::getline(source, line)) {
diff --git a/test/test_platform_util.cpp b/test/test_platform_util.cpp
index caf2e03e..6963c1e6 100644
--- a/test/test_platform_util.cpp
+++ b/test/test_platform_util.cpp
@@ -19,7 +19,9 @@ PLATFORM_UTIL_TEST("find docker container ID") {
       {__LINE__, "empty inputs", "", nullopt},
       {__LINE__, "no docker container ID", "coucou", nullopt},
       {__LINE__, "one line with docker container ID",
-       "0::/system.slice/docker-cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411.scope",
+       "0::/system.slice/"
+       "docker-"
+       "cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411.scope",
        "cde7c2bab394630a42d73dc610b9c57415dced996106665d427f6d0566594411"},
       {__LINE__, "multiline wihtout docker container ID", R"(
 0::/

From 43f214aa4d1199571364670eab64d98defed0233 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 14 Jul 2025 12:58:54 -0700
Subject: [PATCH 05/17] Add temporary logging to stdout and stderr for the
 container-id parsing

---
 src/datadog/platform_util.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 00c50343..d2e94cac 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -3,6 +3,7 @@
 #include <cassert>
 #include <cstdint>
 #include <fstream>
+#include <iostream>
 #include <regex>
 
 // clang-format off
@@ -342,7 +343,10 @@ Optional<Cgroup> get_cgroup_version() {
 
 Optional<std::string> find_container_id_from_cgroup() {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
-  if (!cgroup_fd.is_open()) return nullopt;
+  if (!cgroup_fd.is_open()) {
+    std::cerr << "failed to open /proc/self/cgroup" << std::endl;
+    return nullopt;
+  }
 
   return find_container_id(cgroup_fd);
 }
@@ -361,6 +365,7 @@ Optional<std::string> find_container_id(std::istream& source) {
 
   std::string line;
   while (std::getline(source, line)) {
+    std::cout << "Reading line: " << line << std::endl;
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
     std::smatch match;
@@ -368,10 +373,12 @@ Optional<std::string> find_container_id(std::istream& source) {
       assert(match.ready());
       assert(match.size() == 2);
 
+      std::cout << "Found container ID: " << match.str(1) << std::endl;
       return match.str(1);
     }
   }
 
+  std::cout << "No container ID found" << std::endl;
   return nullopt;
 }
 

From d6e929794c992f899a59a36313cb16f99f58dc3e Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 14 Jul 2025 13:43:01 -0700
Subject: [PATCH 06/17] This doesn't pass unit tests, but now I am writing some
 more helpful logs into our error logging so I can debug why this isn't
 working in system-tests

---
 src/datadog/datadog_agent.cpp |  2 +-
 src/datadog/platform_util.cpp | 29 +++++++++++++++++++----------
 src/datadog/platform_util.h   |  7 +++++--
 test/test_platform_util.cpp   |  5 +++--
 4 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/src/datadog/datadog_agent.cpp b/src/datadog/datadog_agent.cpp
index 6e788ae7..9201822c 100644
--- a/src/datadog/datadog_agent.cpp
+++ b/src/datadog/datadog_agent.cpp
@@ -171,7 +171,7 @@ DatadogAgent::DatadogAgent(
   // Origin Detection headers are not necessary when Unix Domain Socket (UDS)
   // is used to communicate with the Datadog Agent.
   if (!contains(config.url.scheme, "unix")) {
-    if (auto container_id = container::get_id()) {
+    if (auto container_id = container::get_id(logger_)) {
       if (container_id->type == container::ContainerID::Type::container_id) {
         headers_.emplace("Datadog-Container-ID", container_id->value);
         headers_.emplace("Datadog-Entity-Id", "ci-" + container_id->value);
diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index d2e94cac..7061e57c 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -4,6 +4,7 @@
 #include <cstdint>
 #include <fstream>
 #include <iostream>
+#include <memory>
 #include <regex>
 
 // clang-format off
@@ -45,6 +46,8 @@
 #endif
 // clang-format on
 
+#include <datadog/logger.h>
+
 namespace datadog {
 namespace tracing {
 namespace {
@@ -341,19 +344,21 @@ Optional<Cgroup> get_cgroup_version() {
   return nullopt;
 }
 
-Optional<std::string> find_container_id_from_cgroup() {
+Optional<std::string> find_container_id_from_cgroup(
+    const std::shared_ptr<tracing::Logger>& logger) {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
   if (!cgroup_fd.is_open()) {
-    std::cerr << "failed to open /proc/self/cgroup" << std::endl;
+    logger->log_error("failed to open /proc/self/cgroup");
     return nullopt;
   }
 
-  return find_container_id(cgroup_fd);
+  return find_container_id(cgroup_fd, logger);
 }
 #endif
 }  // namespace
 
-Optional<std::string> find_container_id(std::istream& source) {
+Optional<std::string> find_container_id(std::istream& source,
+                                        const std::shared_ptr<tracing::Logger>& logger) {
   static const std::string uuid_regex_str =
       "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
       "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
@@ -365,7 +370,7 @@ Optional<std::string> find_container_id(std::istream& source) {
 
   std::string line;
   while (std::getline(source, line)) {
-    std::cout << "Reading line: " << line << std::endl;
+    logger->log_error("Reading line: " + line);
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
     std::smatch match;
@@ -373,29 +378,33 @@ Optional<std::string> find_container_id(std::istream& source) {
       assert(match.ready());
       assert(match.size() == 2);
 
-      std::cout << "Found container ID: " << match.str(1) << std::endl;
+      logger->log_error("Found container ID: " + match.str(1));
       return match.str(1);
     }
   }
 
-  std::cout << "No container ID found" << std::endl;
+  logger->log_error("No container ID found");
   return nullopt;
 }
 
-Optional<ContainerID> get_id() {
+Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
 #if defined(__linux__) || defined(__unix__)
   if (is_running_in_host_namespace()) {
     // Not in a container, no need to continue.
+    logger->log_error("Not in a container, no need to continue.");
     return nullopt;
   }
 
   auto maybe_cgroup = get_cgroup_version();
-  if (!maybe_cgroup) return nullopt;
+  if (!maybe_cgroup) {
+    logger->log_error("Failed to get cgroup version.");
+    return nullopt;
+  }
 
   ContainerID id;
   switch (*maybe_cgroup) {
     case Cgroup::v1: {
-      if (auto maybe_id = find_container_id_from_cgroup()) {
+      if (auto maybe_id = find_container_id_from_cgroup(logger)) {
         id.value = *maybe_id;
         id.type = ContainerID::Type::container_id;
         break;
diff --git a/src/datadog/platform_util.h b/src/datadog/platform_util.h
index a71d2df6..0f4dca05 100644
--- a/src/datadog/platform_util.h
+++ b/src/datadog/platform_util.h
@@ -3,8 +3,10 @@
 // This component provides platform-dependent miscellanea.
 
 #include <datadog/expected.h>
+#include <datadog/logger.h>
 #include <datadog/string_view.h>
 
+#include <memory>
 #include <string>
 
 namespace datadog {
@@ -90,13 +92,14 @@ struct ContainerID final {
 /// @param source The input from which to read the container ID.
 /// @return An Optional containing the container ID if found, otherwise
 /// nothing.
-Optional<std::string> find_container_id(std::istream& source);
+Optional<std::string> find_container_id(std::istream& source,
+                                        const std::shared_ptr<tracing::Logger>& logger);
 
 /// Function to retrieve the container metadata.
 ///
 /// @return A `ContainerID` object containing id of the container in
 /// which the current process is running.
-Optional<ContainerID> get_id();
+Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger);
 
 }  // namespace container
 
diff --git a/test/test_platform_util.cpp b/test/test_platform_util.cpp
index 6963c1e6..e9a3213a 100644
--- a/test/test_platform_util.cpp
+++ b/test/test_platform_util.cpp
@@ -2,6 +2,7 @@
 
 #include "platform_util.h"
 #include "test.h"
+#include "null_logger.h"
 
 using namespace datadog::tracing;
 
@@ -58,7 +59,7 @@ PLATFORM_UTIL_TEST("find docker container ID") {
 
   std::istringstream is(test_case.input);
 
-  auto maybe_container_id = container::find_container_id(is);
+  auto maybe_container_id = container::find_container_id(is, std::make_shared<NullLogger>());
   if (test_case.expected_container_id.has_value()) {
     REQUIRE(maybe_container_id.has_value());
     CHECK(*maybe_container_id == *test_case.expected_container_id);
@@ -186,7 +187,7 @@ PLATFORM_UTIL_TEST("find multiline container IDs") {
 
   std::istringstream is(test_case.input);
 
-  auto maybe_container_id = container::find_container_id(is);
+  auto maybe_container_id = container::find_container_id(is, std::make_shared<NullLogger>());
   if (test_case.expected_container_id.has_value()) {
     REQUIRE(maybe_container_id.has_value());
     CHECK(*maybe_container_id == *test_case.expected_container_id);

From 6251ac45adfbe6b7b7f43ca7746c62f6146eac4b Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 14 Jul 2025 15:34:58 -0700
Subject: [PATCH 07/17] Remove the host namespace check since it stops us from
 working on Docker Desktop.

---
 src/datadog/platform_util.cpp | 22 +++-------------------
 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 7061e57c..ef0ab82d 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -302,7 +302,7 @@ constexpr uint64_t CGROUP2_SUPER_MAGIC = 0x63677270;
 
 /// Magic number from linux/proc_ns.h:
 /// <https://github.com/torvalds/linux/blob/5859a2b1991101d6b978f3feb5325dad39421f29/include/linux/proc_ns.h#L41-L49>
-constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
+// constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
 
 /// Represents the cgroup version of the current process.
 enum class Cgroup : char { v1, v2 };
@@ -316,19 +316,6 @@ Optional<ino_t> get_inode(std::string_view path) {
   return buf.st_ino;
 }
 
-// Host namespace inode number are hardcoded, which allows for dectection of
-// whether the binary is running in host or not. However, it does not work when
-// running in a Docker in Docker environment.
-bool is_running_in_host_namespace() {
-  // linux procfs file that represents the cgroup namespace of the current
-  // process.
-  if (auto inode = get_inode("/proc/self/ns/cgroup")) {
-    return *inode == HOST_CGROUP_NAMESPACE_INODE;
-  }
-
-  return false;
-}
-
 Optional<Cgroup> get_cgroup_version() {
   struct statfs buf;
 
@@ -389,11 +376,8 @@ Optional<std::string> find_container_id(std::istream& source,
 
 Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
 #if defined(__linux__) || defined(__unix__)
-  if (is_running_in_host_namespace()) {
-    // Not in a container, no need to continue.
-    logger->log_error("Not in a container, no need to continue.");
-    return nullopt;
-  }
+  // Comment out the host namespace check, following the algorithm from other tracers.
+  // This should allow us to detect containers running in Docker Desktop.
 
   auto maybe_cgroup = get_cgroup_version();
   if (!maybe_cgroup) {

From 7fb67c95d30be0898561180887fd424494368307 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 14 Jul 2025 15:59:55 -0700
Subject: [PATCH 08/17] Also remove the eager cgroup lookup because that's
 stopping us from collecting the container-id on Docker Desktop

---
 src/datadog/platform_util.cpp | 52 ++++++++---------------------------
 1 file changed, 11 insertions(+), 41 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index ef0ab82d..3ab4a5d3 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -297,15 +297,15 @@ namespace {
 #if defined(__linux__) || defined(__unix__)
 /// Magic numbers from linux/magic.h:
 /// <https://github.com/torvalds/linux/blob/ca91b9500108d4cf083a635c2e11c884d5dd20ea/include/uapi/linux/magic.h#L71>
-constexpr uint64_t CGROUP_SUPER_MAGIC = 0x27e0eb;
-constexpr uint64_t CGROUP2_SUPER_MAGIC = 0x63677270;
+// constexpr uint64_t CGROUP_SUPER_MAGIC = 0x27e0eb;
+// constexpr uint64_t CGROUP2_SUPER_MAGIC = 0x63677270;
 
 /// Magic number from linux/proc_ns.h:
 /// <https://github.com/torvalds/linux/blob/5859a2b1991101d6b978f3feb5325dad39421f29/include/linux/proc_ns.h#L41-L49>
 // constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
 
 /// Represents the cgroup version of the current process.
-enum class Cgroup : char { v1, v2 };
+// enum class Cgroup : char { v1, v2 };
 
 Optional<ino_t> get_inode(std::string_view path) {
   struct stat buf;
@@ -316,21 +316,6 @@ Optional<ino_t> get_inode(std::string_view path) {
   return buf.st_ino;
 }
 
-Optional<Cgroup> get_cgroup_version() {
-  struct statfs buf;
-
-  if (statfs("/sys/fs/cgroup", &buf) != 0) {
-    return nullopt;
-  }
-
-  if (buf.f_type == CGROUP_SUPER_MAGIC)
-    return Cgroup::v1;
-  else if (buf.f_type == CGROUP2_SUPER_MAGIC)
-    return Cgroup::v2;
-
-  return nullopt;
-}
-
 Optional<std::string> find_container_id_from_cgroup(
     const std::shared_ptr<tracing::Logger>& logger) {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
@@ -377,32 +362,17 @@ Optional<std::string> find_container_id(std::istream& source,
 Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
 #if defined(__linux__) || defined(__unix__)
   // Comment out the host namespace check, following the algorithm from other tracers.
+  // Also don't get the cgroup version upfront, following the algorithm from other tracers.
   // This should allow us to detect containers running in Docker Desktop.
 
-  auto maybe_cgroup = get_cgroup_version();
-  if (!maybe_cgroup) {
-    logger->log_error("Failed to get cgroup version.");
-    return nullopt;
-  }
-
   ContainerID id;
-  switch (*maybe_cgroup) {
-    case Cgroup::v1: {
-      if (auto maybe_id = find_container_id_from_cgroup(logger)) {
-        id.value = *maybe_id;
-        id.type = ContainerID::Type::container_id;
-        break;
-      }
-    }
-      // NOTE(@dmehala): failed to find the container ID, try getting the cgroup
-      // inode.
-      [[fallthrough]];
-    case Cgroup::v2: {
-      if (auto maybe_inode = get_inode("/sys/fs/cgroup")) {
-        id.type = ContainerID::Type::cgroup_inode;
-        id.value = std::to_string(*maybe_inode);
-      }
-    }; break;
+  if (auto maybe_id = find_container_id_from_cgroup(logger)) {
+    id.value = *maybe_id;
+    id.type = ContainerID::Type::container_id;
+  } else if (auto maybe_inode = get_inode("/sys/fs/cgroup")) {
+    // NOTE(@dmehala): failed to find the container ID, try getting the cgroup inode.
+    id.type = ContainerID::Type::cgroup_inode;
+    id.value = std::to_string(*maybe_inode);
   }
 
   return id;

From 70d6db4f5c851aeda972e408c825b804ead9f351 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 14 Jul 2025 16:52:16 -0700
Subject: [PATCH 09/17] Refactor to better align with Java implementation

---
 src/datadog/platform_util.cpp | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 3ab4a5d3..b78b4aa8 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -302,7 +302,7 @@ namespace {
 
 /// Magic number from linux/proc_ns.h:
 /// <https://github.com/torvalds/linux/blob/5859a2b1991101d6b978f3feb5325dad39421f29/include/linux/proc_ns.h#L41-L49>
-// constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
+constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
 
 /// Represents the cgroup version of the current process.
 // enum class Cgroup : char { v1, v2 };
@@ -316,6 +316,19 @@ Optional<ino_t> get_inode(std::string_view path) {
   return buf.st_ino;
 }
 
+// Host namespace inode number are hardcoded, which allows for dectection of
+// whether the binary is running in host or not. However, it does not work when
+// running in a Docker in Docker environment.
+bool is_running_in_host_namespace() {
+  // linux procfs file that represents the cgroup namespace of the current
+  // process.
+  if (auto inode = get_inode("/proc/self/ns/cgroup")) {
+    return *inode == HOST_CGROUP_NAMESPACE_INODE;
+  }
+
+  return false;
+}
+
 Optional<std::string> find_container_id_from_cgroup(
     const std::shared_ptr<tracing::Logger>& logger) {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
@@ -361,18 +374,18 @@ Optional<std::string> find_container_id(std::istream& source,
 
 Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
 #if defined(__linux__) || defined(__unix__)
-  // Comment out the host namespace check, following the algorithm from other tracers.
-  // Also don't get the cgroup version upfront, following the algorithm from other tracers.
-  // This should allow us to detect containers running in Docker Desktop.
-
+  // Determine the container ID or inode
   ContainerID id;
   if (auto maybe_id = find_container_id_from_cgroup(logger)) {
     id.value = *maybe_id;
     id.type = ContainerID::Type::container_id;
-  } else if (auto maybe_inode = get_inode("/sys/fs/cgroup")) {
+  } else if (!is_running_in_host_namespace()) {
     // NOTE(@dmehala): failed to find the container ID, try getting the cgroup inode.
-    id.type = ContainerID::Type::cgroup_inode;
-    id.value = std::to_string(*maybe_inode);
+    auto maybe_inode = get_inode("/sys/fs/cgroup");
+    if (maybe_inode) {
+      id.type = ContainerID::Type::cgroup_inode;
+      id.value = std::to_string(*maybe_inode);
+    }
   }
 
   return id;

From f0abaadd01f42250723de772b61aec623badf8ab Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Mon, 14 Jul 2025 17:01:41 -0700
Subject: [PATCH 10/17] Remove all uses of logger now that we're done debugging
 system-tests issues. Also remove unused code.

---
 src/datadog/datadog_agent.cpp |  2 +-
 src/datadog/platform_util.cpp | 27 +++++----------------------
 src/datadog/platform_util.h   |  7 ++-----
 test/test_platform_util.cpp   |  5 ++---
 4 files changed, 10 insertions(+), 31 deletions(-)

diff --git a/src/datadog/datadog_agent.cpp b/src/datadog/datadog_agent.cpp
index 9201822c..6e788ae7 100644
--- a/src/datadog/datadog_agent.cpp
+++ b/src/datadog/datadog_agent.cpp
@@ -171,7 +171,7 @@ DatadogAgent::DatadogAgent(
   // Origin Detection headers are not necessary when Unix Domain Socket (UDS)
   // is used to communicate with the Datadog Agent.
   if (!contains(config.url.scheme, "unix")) {
-    if (auto container_id = container::get_id(logger_)) {
+    if (auto container_id = container::get_id()) {
       if (container_id->type == container::ContainerID::Type::container_id) {
         headers_.emplace("Datadog-Container-ID", container_id->value);
         headers_.emplace("Datadog-Entity-Id", "ci-" + container_id->value);
diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index b78b4aa8..223b4dba 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -4,7 +4,6 @@
 #include <cstdint>
 #include <fstream>
 #include <iostream>
-#include <memory>
 #include <regex>
 
 // clang-format off
@@ -46,8 +45,6 @@
 #endif
 // clang-format on
 
-#include <datadog/logger.h>
-
 namespace datadog {
 namespace tracing {
 namespace {
@@ -295,18 +292,10 @@ Expected<InMemoryFile> InMemoryFile::make(StringView) {
 namespace container {
 namespace {
 #if defined(__linux__) || defined(__unix__)
-/// Magic numbers from linux/magic.h:
-/// <https://github.com/torvalds/linux/blob/ca91b9500108d4cf083a635c2e11c884d5dd20ea/include/uapi/linux/magic.h#L71>
-// constexpr uint64_t CGROUP_SUPER_MAGIC = 0x27e0eb;
-// constexpr uint64_t CGROUP2_SUPER_MAGIC = 0x63677270;
-
 /// Magic number from linux/proc_ns.h:
 /// <https://github.com/torvalds/linux/blob/5859a2b1991101d6b978f3feb5325dad39421f29/include/linux/proc_ns.h#L41-L49>
 constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
 
-/// Represents the cgroup version of the current process.
-// enum class Cgroup : char { v1, v2 };
-
 Optional<ino_t> get_inode(std::string_view path) {
   struct stat buf;
   if (stat(path.data(), &buf) != 0) {
@@ -329,21 +318,18 @@ bool is_running_in_host_namespace() {
   return false;
 }
 
-Optional<std::string> find_container_id_from_cgroup(
-    const std::shared_ptr<tracing::Logger>& logger) {
+Optional<std::string> find_container_id_from_cgroup() {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
   if (!cgroup_fd.is_open()) {
-    logger->log_error("failed to open /proc/self/cgroup");
     return nullopt;
   }
 
-  return find_container_id(cgroup_fd, logger);
+  return find_container_id(cgroup_fd);
 }
 #endif
 }  // namespace
 
-Optional<std::string> find_container_id(std::istream& source,
-                                        const std::shared_ptr<tracing::Logger>& logger) {
+Optional<std::string> find_container_id(std::istream& source) {
   static const std::string uuid_regex_str =
       "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
       "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
@@ -355,7 +341,6 @@ Optional<std::string> find_container_id(std::istream& source,
 
   std::string line;
   while (std::getline(source, line)) {
-    logger->log_error("Reading line: " + line);
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
     std::smatch match;
@@ -363,20 +348,18 @@ Optional<std::string> find_container_id(std::istream& source,
       assert(match.ready());
       assert(match.size() == 2);
 
-      logger->log_error("Found container ID: " + match.str(1));
       return match.str(1);
     }
   }
 
-  logger->log_error("No container ID found");
   return nullopt;
 }
 
-Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
+Optional<ContainerID> get_id() {
 #if defined(__linux__) || defined(__unix__)
   // Determine the container ID or inode
   ContainerID id;
-  if (auto maybe_id = find_container_id_from_cgroup(logger)) {
+  if (auto maybe_id = find_container_id_from_cgroup()) {
     id.value = *maybe_id;
     id.type = ContainerID::Type::container_id;
   } else if (!is_running_in_host_namespace()) {
diff --git a/src/datadog/platform_util.h b/src/datadog/platform_util.h
index 0f4dca05..a71d2df6 100644
--- a/src/datadog/platform_util.h
+++ b/src/datadog/platform_util.h
@@ -3,10 +3,8 @@
 // This component provides platform-dependent miscellanea.
 
 #include <datadog/expected.h>
-#include <datadog/logger.h>
 #include <datadog/string_view.h>
 
-#include <memory>
 #include <string>
 
 namespace datadog {
@@ -92,14 +90,13 @@ struct ContainerID final {
 /// @param source The input from which to read the container ID.
 /// @return An Optional containing the container ID if found, otherwise
 /// nothing.
-Optional<std::string> find_container_id(std::istream& source,
-                                        const std::shared_ptr<tracing::Logger>& logger);
+Optional<std::string> find_container_id(std::istream& source);
 
 /// Function to retrieve the container metadata.
 ///
 /// @return A `ContainerID` object containing id of the container in
 /// which the current process is running.
-Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger);
+Optional<ContainerID> get_id();
 
 }  // namespace container
 
diff --git a/test/test_platform_util.cpp b/test/test_platform_util.cpp
index e9a3213a..6963c1e6 100644
--- a/test/test_platform_util.cpp
+++ b/test/test_platform_util.cpp
@@ -2,7 +2,6 @@
 
 #include "platform_util.h"
 #include "test.h"
-#include "null_logger.h"
 
 using namespace datadog::tracing;
 
@@ -59,7 +58,7 @@ PLATFORM_UTIL_TEST("find docker container ID") {
 
   std::istringstream is(test_case.input);
 
-  auto maybe_container_id = container::find_container_id(is, std::make_shared<NullLogger>());
+  auto maybe_container_id = container::find_container_id(is);
   if (test_case.expected_container_id.has_value()) {
     REQUIRE(maybe_container_id.has_value());
     CHECK(*maybe_container_id == *test_case.expected_container_id);
@@ -187,7 +186,7 @@ PLATFORM_UTIL_TEST("find multiline container IDs") {
 
   std::istringstream is(test_case.input);
 
-  auto maybe_container_id = container::find_container_id(is, std::make_shared<NullLogger>());
+  auto maybe_container_id = container::find_container_id(is);
   if (test_case.expected_container_id.has_value()) {
     REQUIRE(maybe_container_id.has_value());
     CHECK(*maybe_container_id == *test_case.expected_container_id);

From 565c4e073e87014e135707a223408481d8f5148a Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Tue, 15 Jul 2025 11:30:46 -0700
Subject: [PATCH 11/17] Put back the get_cgroup_version and add temporary
 logging to confirm the f_type returned by the statfs call

---
 src/datadog/datadog_agent.cpp |  2 +-
 src/datadog/platform_util.cpp | 35 ++++++++++++++++++++++++++++++++++-
 src/datadog/platform_util.h   |  4 +++-
 3 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/datadog/datadog_agent.cpp b/src/datadog/datadog_agent.cpp
index 6e788ae7..9201822c 100644
--- a/src/datadog/datadog_agent.cpp
+++ b/src/datadog/datadog_agent.cpp
@@ -171,7 +171,7 @@ DatadogAgent::DatadogAgent(
   // Origin Detection headers are not necessary when Unix Domain Socket (UDS)
   // is used to communicate with the Datadog Agent.
   if (!contains(config.url.scheme, "unix")) {
-    if (auto container_id = container::get_id()) {
+    if (auto container_id = container::get_id(logger_)) {
       if (container_id->type == container::ContainerID::Type::container_id) {
         headers_.emplace("Datadog-Container-ID", container_id->value);
         headers_.emplace("Datadog-Entity-Id", "ci-" + container_id->value);
diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 223b4dba..326a7714 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -4,6 +4,7 @@
 #include <cstdint>
 #include <fstream>
 #include <iostream>
+#include <memory>
 #include <regex>
 
 // clang-format off
@@ -45,6 +46,8 @@
 #endif
 // clang-format on
 
+#include <datadog/logger.h>
+
 namespace datadog {
 namespace tracing {
 namespace {
@@ -292,10 +295,18 @@ Expected<InMemoryFile> InMemoryFile::make(StringView) {
 namespace container {
 namespace {
 #if defined(__linux__) || defined(__unix__)
+/// Magic numbers from linux/magic.h:
+/// <https://github.com/torvalds/linux/blob/ca91b9500108d4cf083a635c2e11c884d5dd20ea/include/uapi/linux/magic.h#L71>
+constexpr uint64_t CGROUP_SUPER_MAGIC = 0x27e0eb;
+constexpr uint64_t CGROUP2_SUPER_MAGIC = 0x63677270;
+
 /// Magic number from linux/proc_ns.h:
 /// <https://github.com/torvalds/linux/blob/5859a2b1991101d6b978f3feb5325dad39421f29/include/linux/proc_ns.h#L41-L49>
 constexpr ino_t HOST_CGROUP_NAMESPACE_INODE = 0xeffffffb;
 
+/// Represents the cgroup version of the current process.
+enum class Cgroup : char { v1, v2 };
+
 Optional<ino_t> get_inode(std::string_view path) {
   struct stat buf;
   if (stat(path.data(), &buf) != 0) {
@@ -318,6 +329,25 @@ bool is_running_in_host_namespace() {
   return false;
 }
 
+Optional<Cgroup> get_cgroup_version(const std::shared_ptr<tracing::Logger>& logger) {
+  struct statfs buf;
+
+  if (statfs("/sys/fs/cgroup", &buf) != 0) {
+    logger->log_error("Failed to statfs /sys/fs/cgroup");
+    return nullopt;
+  }
+
+  logger->log_error([&](auto& stream) {
+    stream << "statfs /sys/fs/cgroup: f_type = " << buf.f_type;
+  });
+  if (buf.f_type == CGROUP_SUPER_MAGIC)
+    return Cgroup::v1;
+  else if (buf.f_type == CGROUP2_SUPER_MAGIC)
+    return Cgroup::v2;
+
+  return nullopt;
+}
+
 Optional<std::string> find_container_id_from_cgroup() {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
   if (!cgroup_fd.is_open()) {
@@ -355,8 +385,11 @@ Optional<std::string> find_container_id(std::istream& source) {
   return nullopt;
 }
 
-Optional<ContainerID> get_id() {
+Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
 #if defined(__linux__) || defined(__unix__)
+  auto maybe_cgroup = get_cgroup_version(logger);
+  if (!maybe_cgroup) return nullopt;
+
   // Determine the container ID or inode
   ContainerID id;
   if (auto maybe_id = find_container_id_from_cgroup()) {
diff --git a/src/datadog/platform_util.h b/src/datadog/platform_util.h
index a71d2df6..2b3c42cb 100644
--- a/src/datadog/platform_util.h
+++ b/src/datadog/platform_util.h
@@ -3,8 +3,10 @@
 // This component provides platform-dependent miscellanea.
 
 #include <datadog/expected.h>
+#include <datadog/logger.h>
 #include <datadog/string_view.h>
 
+#include <memory>
 #include <string>
 
 namespace datadog {
@@ -96,7 +98,7 @@ Optional<std::string> find_container_id(std::istream& source);
 ///
 /// @return A `ContainerID` object containing id of the container in
 /// which the current process is running.
-Optional<ContainerID> get_id();
+Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger);
 
 }  // namespace container
 

From 587405f01679c9b2712ccedbee55f7071acb9ea0 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Wed, 16 Jul 2025 08:27:48 -0700
Subject: [PATCH 12/17] Restore the cgroup logic, but also include TMPFS_MAGIC
 as a valid value for using our  cgroup v1 lookup

---
 src/datadog/platform_util.cpp | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 326a7714..e5f5971b 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -297,6 +297,7 @@ namespace {
 #if defined(__linux__) || defined(__unix__)
 /// Magic numbers from linux/magic.h:
 /// <https://github.com/torvalds/linux/blob/ca91b9500108d4cf083a635c2e11c884d5dd20ea/include/uapi/linux/magic.h#L71>
+constexpr uint64_t TMPFS_MAGIC = 0x01021994;
 constexpr uint64_t CGROUP_SUPER_MAGIC = 0x27e0eb;
 constexpr uint64_t CGROUP2_SUPER_MAGIC = 0x63677270;
 
@@ -340,7 +341,7 @@ Optional<Cgroup> get_cgroup_version(const std::shared_ptr<tracing::Logger>& logg
   logger->log_error([&](auto& stream) {
     stream << "statfs /sys/fs/cgroup: f_type = " << buf.f_type;
   });
-  if (buf.f_type == CGROUP_SUPER_MAGIC)
+  if (buf.f_type == CGROUP_SUPER_MAGIC || buf.f_type == TMPFS_MAGIC)
     return Cgroup::v1;
   else if (buf.f_type == CGROUP2_SUPER_MAGIC)
     return Cgroup::v2;
@@ -392,16 +393,26 @@ Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
 
   // Determine the container ID or inode
   ContainerID id;
-  if (auto maybe_id = find_container_id_from_cgroup()) {
-    id.value = *maybe_id;
-    id.type = ContainerID::Type::container_id;
-  } else if (!is_running_in_host_namespace()) {
-    // NOTE(@dmehala): failed to find the container ID, try getting the cgroup inode.
-    auto maybe_inode = get_inode("/sys/fs/cgroup");
-    if (maybe_inode) {
-      id.type = ContainerID::Type::cgroup_inode;
-      id.value = std::to_string(*maybe_inode);
+  switch (*maybe_cgroup) {
+    case Cgroup::v1: {
+      if (auto maybe_id = find_container_id_from_cgroup()) {
+        id.value = *maybe_id;
+        id.type = ContainerID::Type::container_id;
+        break;
+      }
     }
+      // NOTE(@dmehala): failed to find the container ID, try getting the cgroup
+      // inode.
+      [[fallthrough]];
+    case Cgroup::v2: {
+      if (!is_running_in_host_namespace()) {
+        auto maybe_inode = get_inode("/sys/fs/cgroup");
+        if (maybe_inode) {
+          id.type = ContainerID::Type::cgroup_inode;
+          id.value = std::to_string(*maybe_inode);
+        }
+      }
+    }; break;
   }
 
   return id;

From 08909b1efbecb290ed6166a01978a5d2799c44d5 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Wed, 16 Jul 2025 10:25:03 -0700
Subject: [PATCH 13/17] Remove logging (again) and reduce the diff

---
 src/datadog/datadog_agent.cpp |  2 +-
 src/datadog/platform_util.cpp | 19 ++++---------------
 src/datadog/platform_util.h   |  4 +---
 3 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/src/datadog/datadog_agent.cpp b/src/datadog/datadog_agent.cpp
index 9201822c..6e788ae7 100644
--- a/src/datadog/datadog_agent.cpp
+++ b/src/datadog/datadog_agent.cpp
@@ -171,7 +171,7 @@ DatadogAgent::DatadogAgent(
   // Origin Detection headers are not necessary when Unix Domain Socket (UDS)
   // is used to communicate with the Datadog Agent.
   if (!contains(config.url.scheme, "unix")) {
-    if (auto container_id = container::get_id(logger_)) {
+    if (auto container_id = container::get_id()) {
       if (container_id->type == container::ContainerID::Type::container_id) {
         headers_.emplace("Datadog-Container-ID", container_id->value);
         headers_.emplace("Datadog-Entity-Id", "ci-" + container_id->value);
diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index e5f5971b..23a9dc3f 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -3,8 +3,6 @@
 #include <cassert>
 #include <cstdint>
 #include <fstream>
-#include <iostream>
-#include <memory>
 #include <regex>
 
 // clang-format off
@@ -46,8 +44,6 @@
 #endif
 // clang-format on
 
-#include <datadog/logger.h>
-
 namespace datadog {
 namespace tracing {
 namespace {
@@ -330,17 +326,13 @@ bool is_running_in_host_namespace() {
   return false;
 }
 
-Optional<Cgroup> get_cgroup_version(const std::shared_ptr<tracing::Logger>& logger) {
+Optional<Cgroup> get_cgroup_version() {
   struct statfs buf;
 
   if (statfs("/sys/fs/cgroup", &buf) != 0) {
-    logger->log_error("Failed to statfs /sys/fs/cgroup");
     return nullopt;
   }
 
-  logger->log_error([&](auto& stream) {
-    stream << "statfs /sys/fs/cgroup: f_type = " << buf.f_type;
-  });
   if (buf.f_type == CGROUP_SUPER_MAGIC || buf.f_type == TMPFS_MAGIC)
     return Cgroup::v1;
   else if (buf.f_type == CGROUP2_SUPER_MAGIC)
@@ -351,9 +343,7 @@ Optional<Cgroup> get_cgroup_version(const std::shared_ptr<tracing::Logger>& logg
 
 Optional<std::string> find_container_id_from_cgroup() {
   auto cgroup_fd = std::ifstream("/proc/self/cgroup", std::ios::in);
-  if (!cgroup_fd.is_open()) {
-    return nullopt;
-  }
+  if (!cgroup_fd.is_open()) return nullopt;
 
   return find_container_id(cgroup_fd);
 }
@@ -386,12 +376,11 @@ Optional<std::string> find_container_id(std::istream& source) {
   return nullopt;
 }
 
-Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger) {
+Optional<ContainerID> get_id() {
 #if defined(__linux__) || defined(__unix__)
-  auto maybe_cgroup = get_cgroup_version(logger);
+  auto maybe_cgroup = get_cgroup_version();
   if (!maybe_cgroup) return nullopt;
 
-  // Determine the container ID or inode
   ContainerID id;
   switch (*maybe_cgroup) {
     case Cgroup::v1: {
diff --git a/src/datadog/platform_util.h b/src/datadog/platform_util.h
index 2b3c42cb..a71d2df6 100644
--- a/src/datadog/platform_util.h
+++ b/src/datadog/platform_util.h
@@ -3,10 +3,8 @@
 // This component provides platform-dependent miscellanea.
 
 #include <datadog/expected.h>
-#include <datadog/logger.h>
 #include <datadog/string_view.h>
 
-#include <memory>
 #include <string>
 
 namespace datadog {
@@ -98,7 +96,7 @@ Optional<std::string> find_container_id(std::istream& source);
 ///
 /// @return A `ContainerID` object containing id of the container in
 /// which the current process is running.
-Optional<ContainerID> get_id(const std::shared_ptr<tracing::Logger>& logger);
+Optional<ContainerID> get_id();
 
 }  // namespace container
 

From 376793e51751608a1dbd7fda1e93266c0f260498 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Wed, 16 Jul 2025 10:31:31 -0700
Subject: [PATCH 14/17] Restore the previous substring approach and execute
 this first before invoking regex matching

---
 src/datadog/platform_util.cpp | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 23a9dc3f..e0b8a932 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -351,6 +351,7 @@ Optional<std::string> find_container_id_from_cgroup() {
 }  // namespace
 
 Optional<std::string> find_container_id(std::istream& source) {
+  constexpr std::string_view docker_str = "docker-";
   static const std::string uuid_regex_str =
       "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
       "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
@@ -361,6 +362,28 @@ Optional<std::string> find_container_id(std::istream& source) {
                                    ")(?:\\.scope)?$");
 
   std::string line;
+
+  // First, iterate using the simple substring match.
+  while (std::getline(source, line)) {
+    // Example:
+    // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
+    if (auto beg = line.find(docker_str); beg != std::string::npos) {
+      beg += docker_str.size();
+      auto end = line.find(".scope", beg);
+      if (end == std::string::npos || end - beg <= 0) {
+        continue;
+      }
+
+      auto container_id = line.substr(beg, end - beg);
+      return container_id;
+    }
+  }
+
+  // Reset the stream to the beginning.
+  source.clear();
+  source.seekg(0);
+
+  // If no match is found, iterate using the regex match.
   while (std::getline(source, line)) {
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`

From 039883aca953801c721b43292936c2a939ea280c Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Wed, 16 Jul 2025 14:36:15 -0700
Subject: [PATCH 15/17] Apply suggestions from code review

Co-authored-by: Damien Mehala <damien.mehala@datadoghq.com>
---
 src/datadog/platform_util.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index e0b8a932..5a405e25 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -363,7 +363,7 @@ Optional<std::string> find_container_id(std::istream& source) {
 
   std::string line;
 
-  // First, iterate using the simple substring match.
+  // Look for Docker container IDs in the basic format: `docker-<uuid>.scope`.
   while (std::getline(source, line)) {
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
@@ -383,12 +383,13 @@ Optional<std::string> find_container_id(std::istream& source) {
   source.clear();
   source.seekg(0);
 
-  // If no match is found, iterate using the regex match.
+  // Perform a second pass using a regular expression for matching container IDs in a Fargate environment. 
+  // This two-step approach is used because STL `regex` is relatively slow, so we avoid using it unless necessary.
   while (std::getline(source, line)) {
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
     std::smatch match;
-    if (std::regex_match(line, match, path_reg)) {
+    if (std::regex_match(line, match, path_reg) && match.size() == 2) {
       assert(match.ready());
       assert(match.size() == 2);
 

From d8576b981b1929c95bf77dc75d83f96c298a901d Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Wed, 16 Jul 2025 15:24:55 -0700
Subject: [PATCH 16/17] Move the regex string literals closer to their usage

---
 src/datadog/platform_util.cpp | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index 5a405e25..ad58e855 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -351,19 +351,11 @@ Optional<std::string> find_container_id_from_cgroup() {
 }  // namespace
 
 Optional<std::string> find_container_id(std::istream& source) {
-  constexpr std::string_view docker_str = "docker-";
-  static const std::string uuid_regex_str =
-      "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
-      "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
-  static const std::string container_regex_str = "[0-9a-f]{64}";
-  static const std::string task_regex_str = "[0-9a-f]{32}-\\d+";
-  static const std::regex path_reg("(?:.+)?(" + uuid_regex_str + "|" +
-                                   container_regex_str + "|" + task_regex_str +
-                                   ")(?:\\.scope)?$");
-
   std::string line;
 
   // Look for Docker container IDs in the basic format: `docker-<uuid>.scope`.
+  constexpr std::string_view docker_str = "docker-";
+
   while (std::getline(source, line)) {
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`
@@ -385,6 +377,15 @@ Optional<std::string> find_container_id(std::istream& source) {
 
   // Perform a second pass using a regular expression for matching container IDs in a Fargate environment. 
   // This two-step approach is used because STL `regex` is relatively slow, so we avoid using it unless necessary.
+  static const std::string uuid_regex_str =
+      "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
+      "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";
+  static const std::string container_regex_str = "[0-9a-f]{64}";
+  static const std::string task_regex_str = "[0-9a-f]{32}-\\d+";
+  static const std::regex path_reg("(?:.+)?(" + uuid_regex_str + "|" +
+                                   container_regex_str + "|" + task_regex_str +
+                                   ")(?:\\.scope)?$");
+
   while (std::getline(source, line)) {
     // Example:
     // `0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope`

From 9d1946b3a2fa18c28caf42fd3542e7f0e3a7d572 Mon Sep 17 00:00:00 2001
From: Zach Montoya <zach.montoya@datadoghq.com>
Date: Wed, 16 Jul 2025 15:26:48 -0700
Subject: [PATCH 17/17] Fix formatting

---
 src/datadog/platform_util.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/datadog/platform_util.cpp b/src/datadog/platform_util.cpp
index ad58e855..854c1178 100644
--- a/src/datadog/platform_util.cpp
+++ b/src/datadog/platform_util.cpp
@@ -375,8 +375,9 @@ Optional<std::string> find_container_id(std::istream& source) {
   source.clear();
   source.seekg(0);
 
-  // Perform a second pass using a regular expression for matching container IDs in a Fargate environment. 
-  // This two-step approach is used because STL `regex` is relatively slow, so we avoid using it unless necessary.
+  // Perform a second pass using a regular expression for matching container IDs
+  // in a Fargate environment. This two-step approach is used because STL
+  // `regex` is relatively slow, so we avoid using it unless necessary.
   static const std::string uuid_regex_str =
       "[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
       "|(?:[0-9a-f]{8}(?:-[0-9a-f]{4}){4}$)";