[CONTINT-3905] Make sure we retrieve the cgroup inode when the cid is…

… not found
DataDog · Mar 8, 2024 · 9d92025 · 9d92025
2 parents 208eafd + 3f5998a
commit 9d92025
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Showing 4 changed files with 96 additions and 17 deletions.
diff --git a/statsd/container_linux.go b/statsd/container_linux.go
@@ -184,23 +184,27 @@ func inodeForPath(path string) string {
 
 // internalInitContainerID initializes the container ID.
 // It can either be provided by the user or read from cgroups.
-func internalInitContainerID(userProvidedID string, cgroupFallback bool) {
+func internalInitContainerID(userProvidedID string, cgroupFallback, isHostCgroupNs bool) {
 	initOnce.Do(func() {
-		if userProvidedID != "" {
-			containerID = userProvidedID
+		readCIDOrInode(userProvidedID, cgroupPath, selfMountInfoPath, defaultCgroupMountPath, cgroupFallback, isHostCgroupNs)
+	})
+}
+
+// readCIDOrInode reads the container ID from the user provided ID, cgroups or mountinfo.
+func readCIDOrInode(userProvidedID, cgroupPath, selfMountInfoPath, defaultCgroupMountPath string, cgroupFallback, isHostCgroupNs bool) {
+	if userProvidedID != "" {
+		containerID = userProvidedID
+		return
+	}
+
+	if cgroupFallback {
+		if isHostCgroupNs {
+			containerID = readContainerID(cgroupPath)
 			return
 		}
-
-		if cgroupFallback {
-			isHostCgroupNs := isHostCgroupNamespace()
-			if isHostCgroupNs {
-				containerID = readContainerID(cgroupPath)
-				return
-			}
-			containerID = readMountinfo(selfMountInfoPath)
-			if containerID != "" {
-				containerID = getCgroupInode(defaultCgroupMountPath, cgroupPath)
-			}
+		containerID = readMountinfo(selfMountInfoPath)
+		if containerID == "" {
+			containerID = getCgroupInode(defaultCgroupMountPath, cgroupPath)
 		}
-	})
+	}
 }
diff --git a/statsd/container_stub.go b/statsd/container_stub.go
@@ -3,7 +3,11 @@
 
 package statsd
 
-var initContainerID = func(userProvidedID string, cgroupFallback bool) {
+func isHostCgroupNamespace() bool {
+	return false
+}
+
+var initContainerID = func(userProvidedID string, _, _ bool) {
 	initOnce.Do(func() {
 		if userProvidedID != "" {
 			containerID = userProvidedID

diff --git a/statsd/container_test.go b/statsd/container_test.go
@@ -400,3 +400,74 @@ func TestGetCgroupInode(t *testing.T) {
 		})
 	}
 }
+
+func TestReadCIDOrInode(t *testing.T) {
+	tests := []struct {
+		description           string
+		procSelfCgroupContent string
+		mountInfoContent      string
+		isHostCgroupNs        bool
+		expectedResult        string
+		cgroupNodeDir         string
+	}{
+		{
+			description:           "extract container-id from /proc/self/cgroup",
+			procSelfCgroupContent: "4:blkio:/kubepods/burstable/podfd52ef25-a87d-11e9-9423-0800271a638e/8c046cb0b72cd4c99f51b5591cd5b095967f58ee003710a45280c28ee1a9c7fa\n",
+			isHostCgroupNs:        true,
+			expectedResult:        "8c046cb0b72cd4c99f51b5591cd5b095967f58ee003710a45280c28ee1a9c7fa", // Will be formatted with inode number
+		},
+
+		{
+			description:      "extract container-id from mountinfo",
+			mountInfoContent: "2282 2269 8:1 /var/lib/containerd/io.containerd.grpc.v1.cri/sandboxes/c0a82a3506b0366c9666f6dbe71c783abeb26ba65e312e918a49e10a277196d0/hostname /host/var/run/containerd/io.containerd.runtime.v2.task/k8s.io/fc7038bc73a8d3850c66ddbfb0b2901afa378bfcbb942cc384b051767e4ac6b0/rootfs/etc/hostname rw,nosuid,nodev,relatime - ext4 /dev/sda1 rw,commit=30\n",
+			expectedResult:   "fc7038bc73a8d3850c66ddbfb0b2901afa378bfcbb942cc384b051767e4ac6b0",
+		},
+		{
+			description:           "extract inode",
+			cgroupNodeDir:         "system.slice/docker-abcdef0123456789abcdef0123456789.scope",
+			procSelfCgroupContent: "0::/system.slice/docker-abcdef0123456789abcdef0123456789.scope\n",
+			expectedResult:        "in-%d",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.description, func(t *testing.T) {
+			prevContainerID := containerID
+			defer func() {
+				containerID = prevContainerID
+			}()
+
+			sysFsCgroupPath := path.Join(os.TempDir(), "sysfscgroup")
+			groupControllerPath := path.Join(sysFsCgroupPath, tc.cgroupNodeDir)
+			err := os.MkdirAll(groupControllerPath, 0755)
+			require.NoError(t, err)
+			defer os.RemoveAll(groupControllerPath)
+
+			stat, err := os.Stat(groupControllerPath)
+			require.NoError(t, err)
+			expectedResult := tc.expectedResult
+			if strings.HasPrefix(tc.expectedResult, "in-") {
+				expectedResult = fmt.Sprintf(tc.expectedResult, stat.Sys().(*syscall.Stat_t).Ino)
+			}
+
+			procSelfCgroup, err := ioutil.TempFile("", "procselfcgroup")
+			require.NoError(t, err)
+			defer os.Remove(procSelfCgroup.Name())
+			_, err = procSelfCgroup.WriteString(tc.procSelfCgroupContent)
+			require.NoError(t, err)
+			err = procSelfCgroup.Close()
+			require.NoError(t, err)
+
+			mountInfo, err := ioutil.TempFile("", "mountInfo")
+			require.NoError(t, err)
+			defer os.Remove(mountInfo.Name())
+			_, err = mountInfo.WriteString(tc.mountInfoContent)
+			require.NoError(t, err)
+			err = mountInfo.Close()
+			require.NoError(t, err)
+
+			readCIDOrInode("", procSelfCgroup.Name(), mountInfo.Name(), sysFsCgroupPath, true, tc.isHostCgroupNs)
+			require.Equal(t, expectedResult, containerID)
+		})
+	}
+}
diff --git a/statsd/statsd.go b/statsd/statsd.go
@@ -466,7 +466,7 @@ func newWithWriter(w Transport, o *Options, writerName string) (*Client, error)
 	}
 
 	if !hasEntityID {
-		initContainerID(o.containerID, isOriginDetectionEnabled(o, hasEntityID))
+		initContainerID(o.containerID, isOriginDetectionEnabled(o, hasEntityID), isHostCgroupNamespace())
 	}
 
 	isUDS := writerName == writerNameUDS