From f027da4d6415d8c440c8d9680e5db5ae95b747a1 Mon Sep 17 00:00:00 2001
From: Wassim DHIF <wassim.dhif@datadoghq.com>
Date: Wed, 17 Jan 2024 17:27:45 +0100
Subject: [PATCH] Add controller priority unittest

Signed-off-by: Wassim DHIF <wassim.dhif@datadoghq.com>
---
 datadog/dogstatsd/container.py         |  5 ++--
 tests/unit/dogstatsd/test_container.py | 41 ++++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/datadog/dogstatsd/container.py b/datadog/dogstatsd/container.py
index 94b5be2b6..93bb819b5 100644
--- a/datadog/dogstatsd/container.py
+++ b/datadog/dogstatsd/container.py
@@ -33,7 +33,7 @@ class Cgroup(object):
     CGROUP_NS_PATH = "/proc/self/ns/cgroup"  # path to the cgroup namespace file.
     CGROUPV1_BASE_CONTROLLER = "memory"  # controller used to identify the container-id in cgroup v1 (memory).
     CGROUPV2_BASE_CONTROLLER = ""  # controller used to identify the container-id in cgroup v2.
-    HOST_CGROUP_NAMESPACE_INODE = "0xEFFFFFFBL"  # inode of the host cgroup namespace.
+    HOST_CGROUP_NAMESPACE_INODE = 0xEFFFFFFB  # inode of the host cgroup namespace.
 
     UUID_SOURCE = r"[0-9a-f]{8}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{4}[-_][0-9a-f]{12}"
     CONTAINER_SOURCE = r"[0-9a-f]{64}"
@@ -105,6 +105,7 @@ def _get_cgroup_from_inode(self):
                 )
                 inode = os.stat(inode_path).st_ino
                 # 0 is not a valid inode. 1 is a bad block inode and 2 is the root of a filesystem.
-                return "in-{0}".format(inode) if int(inode) > 2 else None
+                if inode > 2:
+                    return "in-{0}".format(inode)
 
         return None
diff --git a/tests/unit/dogstatsd/test_container.py b/tests/unit/dogstatsd/test_container.py
index 3cf3da753..2d0ceeea1 100644
--- a/tests/unit/dogstatsd/test_container.py
+++ b/tests/unit/dogstatsd/test_container.py
@@ -130,7 +130,7 @@ def test_container_id_from_cgroup(file_contents, expected_container_id):
         if file_contents is None:
             mock_open.side_effect = IOError
 
-        with mock.patch("os.stat", mock.MagicMock(return_value=mock.Mock(st_ino="0xEFFFFFFBL"))):
+        with mock.patch("os.stat", mock.MagicMock(return_value=mock.Mock(st_ino=0xEFFFFFFB))):
             reader = Cgroup()
         assert expected_container_id == reader.container_id
 
@@ -140,7 +140,44 @@ def test_container_id_from_cgroup(file_contents, expected_container_id):
 def test_container_id_inode():
     """Test that the inode is returned when the container ID cannot be found."""
     with mock.patch("datadog.dogstatsd.container.open", mock.mock_open(read_data="0::/")) as mock_open:
-        with mock.patch("os.stat", mock.MagicMock(return_value=mock.Mock(st_ino="1234"))):
+        with mock.patch("os.stat", mock.MagicMock(return_value=mock.Mock(st_ino=1234))):
+            reader = Cgroup()
+        assert reader.container_id == "in-1234"
+        mock_open.assert_called_once_with("/proc/self/cgroup", mode="r")
+
+    cgroupv1_priority = """
+12:cpu,cpuacct:/
+11:hugetlb:/
+10:devices:/
+9:rdma:/
+8:net_cls,net_prio:/
+7:memory:/
+6:cpuset:/
+5:pids:/
+4:freezer:/
+3:perf_event:/
+2:blkio:/
+1:name=systemd:/
+0::/
+"""
+
+    memory_priority_valid = False
+
+    def inode_stat_mock(path):
+        nonlocal memory_priority_valid
+        if not memory_priority_valid:
+            # Priority is given to the cgroupv1 controller.
+            assert path == "/sys/fs/cgroup/memory/"
+            memory_priority_valid = True
+
+        # The cgroupv1 controller is mounted on inode 0. This will cause a fallback to the cgroupv2 controller.
+        if path == "/sys/fs/cgroup/memory/":
+            return mock.Mock(st_ino=0)
+        elif path == "/sys/fs/cgroup/":
+            return mock.Mock(st_ino=1234)
+
+    with mock.patch("datadog.dogstatsd.container.open", mock.mock_open(read_data=cgroupv1_priority)) as mock_open:
+        with mock.patch("os.stat", mock.MagicMock(side_effect=inode_stat_mock)):
             reader = Cgroup()
         assert reader.container_id == "in-1234"
         mock_open.assert_called_once_with("/proc/self/cgroup", mode="r")