Merge pull request #1529 from newrelic/cgroupsv2-containerID

Cgroupsv2 container

newrelic-agent/src/main/java/com/newrelic/agent/utilization/CGroup.java

@@ -0,0 +1,6 @@
+package com.newrelic.agent.utilization;
+
+public enum CGroup {
+    V1,
+    V2
+}

newrelic-agent/src/main/java/com/newrelic/agent/utilization/DockerData.java

@@ -20,52 +20,60 @@
 import java.util.regex.Pattern;
 
 /*
- * Grabs the docker container id from the file /proc/self/cgroup. The lines look something like below:
+ * Grabs the docker container id.
+ * For newer Linux systems running cgroup v2, this is taken from /proc/self/mountinfo. The line should look like:
+ *
+ *   594 576 254:1 /docker/containers/f37a7e4d17017e7bf994656b19ca4360c6cdc4951c86700a464101d0d9ce97ef/hosts /etc/hosts rw,relatime - ext4 /dev/vda1 rw,discard
+ *
+ * For older Linux systems running cgroup v1, this is taken from /proc/self/cgroup. The line should look like:
  *
  *   +4:cpu:/docker/3ccfa00432798ff38f85839de1e396f771b4acbe9f4ddea0a761c39b9790a782
  *
  *   We should grab the "cpu" line. The long id number is the number we want.
- *   This is the full docker id, not the short id that appears when you run a "docker ps".
+ *
+ * In either case, this is the full docker id, not the short id that appears when you run a "docker ps".
  */
 public class DockerData {
 
-    private static final String FILE_WITH_CONTAINER_ID = "/proc/self/cgroup";
+    private static final String FILE_WITH_CONTAINER_ID_V1 = "/proc/self/cgroup";
+    private static final String FILE_WITH_CONTAINER_ID_V2 = "/proc/self/mountinfo";
     private static final String CPU = "cpu";
 
     private static final Pattern VALID_CONTAINER_ID = Pattern.compile("^[0-9a-f]{64}$");
-    private static final Pattern DOCKER_CONTAINER_STRING = Pattern.compile("^.*[^0-9a-f]+([0-9a-f]{64,}).*");
+    private static final Pattern DOCKER_CONTAINER_STRING_V1 = Pattern.compile("^.*[^0-9a-f]+([0-9a-f]{64,}).*");
+    private static final Pattern DOCKER_CONTAINER_STRING_V2 = Pattern.compile(".*/docker/containers/([0-9a-f]{64,}).*");
 
     public String getDockerContainerId(boolean isLinux) {
         if (isLinux) {
-            File cpuInfoFile;
-            cpuInfoFile = new File(FILE_WITH_CONTAINER_ID);
-            return getDockerIdFromFile(cpuInfoFile);
+            //try to get the container id from the v2 location
+            File containerIdFileV2 = new File(FILE_WITH_CONTAINER_ID_V2);
+            String idResultV2 = getDockerIdFromFile(containerIdFileV2, CGroup.V2);
+            if (idResultV2 != null) {
+                return idResultV2;
+            }
+            //try to get container id from the v1 location
+            File containerIdFileV1 = new File(FILE_WITH_CONTAINER_ID_V1);
+            return getDockerIdFromFile(containerIdFileV1, CGroup.V1);
         }
         return null;
     }
 
-    String getDockerIdFromFile(File cpuInfoFile) {
-        if (cpuInfoFile.exists() && cpuInfoFile.canRead()) {
+    String getDockerIdFromFile(File mountInfoFile, CGroup cgroup) {
+        if (mountInfoFile.exists() && mountInfoFile.canRead()) {
             try {
-                return readFile(new FileReader(cpuInfoFile));
+                return readFile(new FileReader(mountInfoFile), cgroup);
             } catch (FileNotFoundException e) {
             }
         }
         return null;
     }
 
-    /*
-     * protected for testing.
-     *
-     * Returns the docker id as a string, or null if this value could not be read, or failed validation.
-     */
-    String readFile(Reader reader) {
+    String readFile(Reader reader, CGroup cgroup) {
         try (BufferedReader bReader = new BufferedReader(reader)) {
-
             String line;
             StringBuilder resultGoesHere = new StringBuilder();
             while ((line = bReader.readLine()) != null) {
-                if (checkLineAndGetResult(line, resultGoesHere)) {
+                if (checkLineAndGetResult(line, resultGoesHere, cgroup)) {
                     String value = resultGoesHere.toString().trim();
                     if (isInvalidDockerValue(value)) {
                         Agent.LOG.log(Level.WARNING, MessageFormat.format("Failed to validate Docker value {0}", value));
@@ -80,28 +88,46 @@ String readFile(Reader reader) {
         return null;
     }
 
-    boolean isInvalidDockerValue(String value) {
-        /*
-         * Value should be exactly 64 characters.
-         *
-         * Value is expected to include only [0-9a-f]
-         */
-        return (value == null) || (!VALID_CONTAINER_ID.matcher(value).matches());
+    boolean checkLineAndGetResult(String line, StringBuilder resultGoesHere, CGroup cgroup) {
+        if (cgroup == CGroup.V1) {
+            return checkLineAndGetResultV1(line, resultGoesHere);
+        } else if (cgroup == CGroup.V2) {
+            return checkLineAndGetResultV2(line, resultGoesHere);
+        }
+        return false;
     }
 
-    // protected for testing
-    boolean checkLineAndGetResult(String line, StringBuilder resultGoesHere) {
+   private  boolean checkLineAndGetResultV1(String line, StringBuilder resultGoesHere) {
         String[] parts = line.split(":");
         if (parts.length == 3 && validCpuLine(parts[1])) {
             String mayContainId = parts[2];
-            if (checkAndGetMatch(DOCKER_CONTAINER_STRING, resultGoesHere, mayContainId)) {
+            if (checkAndGetMatch(DOCKER_CONTAINER_STRING_V1, resultGoesHere, mayContainId)) {
                 return true;
             } else if (!mayContainId.equals("/")) {
                 Agent.LOG.log(Level.FINE, "Docker Data: Ignoring unrecognized cgroup ID format: {0}", mayContainId);
             }
         }
         return false;
     }
+    private boolean checkLineAndGetResultV2(String line, StringBuilder resultGoesHere) {
+        String[] parts = line.split(" ");
+        if (parts.length >= 4 ) {
+            String mayContainId = parts[3];
+            if (checkAndGetMatch(DOCKER_CONTAINER_STRING_V2, resultGoesHere, mayContainId)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    boolean isInvalidDockerValue(String value) {
+        /*
+         * Value should be exactly 64 characters.
+         *
+         * Value is expected to include only [0-9a-f]
+         */
+        return (value == null) || (!VALID_CONTAINER_ID.matcher(value).matches());
+    }
 
     private boolean validCpuLine(String segment) {
         if (segment != null) {
@@ -115,6 +141,9 @@ private boolean validCpuLine(String segment) {
         return false;
     }
 
+    /*
+    * Get the match for the capture group of a single-capture-group regex expression.
+     */
     private boolean checkAndGetMatch(Pattern p, StringBuilder result, String segment) {
         Matcher m = p.matcher(segment);
         if (m.matches() && m.groupCount() == 1) {
@@ -123,4 +152,6 @@ private boolean checkAndGetMatch(Pattern p, StringBuilder result, String segment
         }
         return false;
     }
+
+
 }