fix container ID parsing for cgroup v1 in EKS-Fargate (#11110)

fix container ID parsing for cgroup v1 in EKS-Fargate

simplify code by centralizing logic

Co-authored-by: raphael.vandon <raphael.vandon@datadoghq.com>

Author: vandonr

utils/container-utils/src/main/java/datadog/common/container/ContainerInfo.java

@@ -252,14 +252,37 @@ public static ContainerInfo parse(final String cgroupsContent) throws ParseExcep
         containerInfo.setPodId(cGroupInfo.getPodId());
       }
 
-      if (cGroupInfo.getContainerId() != null) {
-        containerInfo.setContainerId(cGroupInfo.getContainerId());
-      }
+      replaceContainerIdIfBetter(containerInfo, cGroupInfo);
     }
 
     return containerInfo;
   }
 
+  /**
+   * Keeps the best available container id candidate across cgroup lines.
+   *
+   * <p>Some environments expose both detailed cgroup-v1 controller paths and a cgroup-v2 membership
+   * path (0::...) where the tail can be task-level and less specific.
+   */
+  private static void replaceContainerIdIfBetter(
+      ContainerInfo currentContainerInfo, CGroupInfo candidate) {
+    String candidateContainerId = candidate.getContainerId();
+    if (candidateContainerId == null) return;
+
+    String currentContainerId = currentContainerInfo.getContainerId();
+    if (currentContainerId != null
+        && currentContainerId.matches(CONTAINER_REGEX)
+        && candidateContainerId.matches(TASK_REGEX)
+        && currentContainerInfo.getPodId() != null
+        && candidate.getPodId() == null) {
+      // Do not replace a pod-scoped container id with a task-scoped id from a less specific path.
+      // This protects hybrid cgroup output where trailing 0:: lines contain only task ids.
+      return;
+    }
+
+    currentContainerInfo.setContainerId(candidateContainerId);
+  }
+
   static CGroupInfo parseLine(final String line) throws ParseException {
     final Matcher matcher = LINE_PATTERN.matcher(line);
 

utils/container-utils/src/test/groovy/datadog/common/container/ContainerInfoTest.groovy

@@ -166,6 +166,21 @@ class ContainerInfoTest extends DDSpecification {
 2:memory:/ecs/55091c13-b8cf-4801-b527-f4601742204d/432624d2150b349fe35ba397284dea788c2bf66b885d14dfc1569b01890ca7da
 1:name=systemd:/ecs/34dc0b5e626f2c5c4c5170e34b10e765-1234567890"""
 
+    // EKS Fargate cgroup with trailing cgroup v2 membership entry (0::...)
+    "cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc" | "defa568d-ff14-43d9-9a63-9e39ee9b39b4" | 13 | """12:misc:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+11:cpuset:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+10:perf_event:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+9:blkio:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+8:net_cls,net_prio:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+7:memory:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+6:cpu,cpuacct:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+5:pids:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+4:devices:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+3:hugetlb:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+2:freezer:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+1:name=systemd:/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393/kubepods/burstable/poddefa568d-ff14-43d9-9a63-9e39ee9b39b4/cf1241bbf80ea91eebdd28bf719057380997ca4b0cea16869393b905fb6d52bc
+0::/ecs/545b896a072744d186c7fb09a45ec172/545b896a072744d186c7fb09a45ec172-3057940393"""
+
     // PCF file
     "6f265890-5165-7fab-6b52-18d1" | null                                   | 12   | """12:rdma:/
 11:net_cls,net_prio:/garden/6f265890-5165-7fab-6b52-18d1