Added CGroupv2 support into Docker Extensions

src/OpenTelemetry.Extensions.Docker/Resources/DockerResourceDetector.cs

@@ -28,6 +28,8 @@ namespace OpenTelemetry.Extensions.Docker.Resources;
 public class DockerResourceDetector : IResourceDetector
 {
     private const string FILEPATH = "/proc/self/cgroup";
+    private const string FILEPATHV2 = "/proc/self/mountinfo";
+    private const string HOSTNAME = "hostname";
 
     /// <summary>
     /// Detects the resource attributes from Docker.
@@ -41,7 +43,7 @@ public Resource Detect()
     /// <summary>
     /// Builds the resource attributes from Container Id in file path.
     /// </summary>
-    /// <param name="path">File path where container id exists.</param>
+    /// <param name="path">cgroup path.</param>
     /// <returns>Returns Resource with list of key-value pairs of container resource attributes if container id exists else empty resource.</returns>
     internal Resource BuildResource(string path)
     {
@@ -60,9 +62,28 @@ internal Resource BuildResource(string path)
     /// <summary>
     /// Extracts Container Id from path.
     /// </summary>
+    /// /// <param name="path">cgroup path.</param>
+    /// <returns>Returns Resource with list of key-value pairs of container resource attributes if container id exists else empty resource.</returns>
+    private string ExtractContainerId(string path)
+    {
+        try
+        {
+            return this.ExtractContainerIdV1(path) ?? this.ExtractContainerIdV2(path);
+        }
+        catch (Exception ex)
+        {
+            DockerExtensionsEventSource.Log.ExtractResourceAttributesException($"{nameof(DockerResourceDetector)} : Failed to extract Container id from path", ex);
+        }
+
+        return null;
+    }
+
+    /// <summary>
+    /// Extracts Container Id from path using the cgroupv1 format.
+    /// </summary>
     /// <param name="path">cgroup path.</param>
     /// <returns>Container Id, Null if not found or exception being thrown.</returns>
-    private string ExtractContainerId(string path)
+    private string ExtractContainerIdV1(string path)
     {
         try
         {
@@ -88,6 +109,37 @@ private string ExtractContainerId(string path)
         return null;
     }
 
+    /// <summary>
+    /// Extracts Container Id from path using the cgroupv2 format.
+    /// </summary>
+    /// <param name="path">File path where container id exists.</param>
+    /// <returns>Returns Resource with list of key-value pairs of container resource attributes if container id exists else empty resource.</returns>
+    private string ExtractContainerIdV2(string path)
+    {
+        try
+        {
+            if (!File.Exists(path))
+            {
+                return null;
+            }
+
+            foreach (string line in File.ReadLines(path))
+            {
+                string containerId = (!string.IsNullOrEmpty(line) && line.Contains(HOSTNAME)) ? this.GetIdFromLineV2(line) : null;
+                if (!string.IsNullOrEmpty(containerId))
+                {
+                    return containerId;
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            DockerExtensionsEventSource.Log.ExtractResourceAttributesException($"{nameof(DockerResourceDetector)} : Failed to extract Container id from path", ex);
+        }
+
+        return null;
+    }
+
     /// <summary>
     /// Gets the Container Id from the line after removing the prefix and suffix.
     /// </summary>
@@ -116,6 +168,27 @@ private string GetIdFromLine(string line)
         return containerId;
     }
 
+    private string GetIdFromLineV2(string line)
+    {
+        int hostnameIndex = line.LastIndexOf("/" + HOSTNAME);
+        if (hostnameIndex < 0)
+        {
+            return null;
+        }
+
+        string earlierSection = line.Substring(0, hostnameIndex);
+        int startIndex = earlierSection.LastIndexOf('/');
+
+        string containerId = this.RemovePrefixAndSuffixIfneeded(earlierSection, startIndex, hostnameIndex);
+
+        if (string.IsNullOrEmpty(containerId) || !EncodingUtils.IsValidHexString(containerId))
+        {
+            return null;
+        }
+
+        return containerId;
+    }
+
     private string RemovePrefixAndSuffixIfneeded(string input, int startIndex, int endIndex)
     {
         startIndex = (startIndex == -1) ? 0 : startIndex + 1;

test/OpenTelemetry.Extensions.Docker.Tests/Resources/DockerResourceDetectorTests.cs

@@ -57,6 +57,14 @@ public class DockerResourceDetectorTests
     private const string CONTAINERID =
         "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356";
 
+    // cgroupv2 line with container Id
+    private const string CGROUPLINEV2 =
+        "13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356/hostname";
+
+    // Expected Container Id
+    private const string CONTAINERIDV2 = "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356";
+
+
     [Fact]
     public void TestValidContainer()
     {
@@ -85,6 +93,12 @@ public void TestValidContainer()
             tempFile.Write(CGROUPLINE);
             Assert.Equal(CONTAINERID, this.GetContainerId(dockerResourceDetector.BuildResource(tempFile.FilePath)));
         }
+
+        using (TempFile tempFile = new TempFile())
+        {
+            tempFile.Write(CGROUPLINEV2);
+            Assert.Equal(CONTAINERIDV2, this.GetContainerId(dockerResourceDetector.BuildResource(tempFile.FilePath)));
+        }
     }
 
     [Fact]