parse container ID with cgroups v2

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/metadata/SystemInfo.java

@@ -43,11 +43,18 @@
 public class SystemInfo {
     private static final Logger logger = LoggerFactory.getLogger(SystemInfo.class);
 
-    private static final String CONTAINER_UID_REGEX = "^[0-9a-fA-F]{64}$";
+    private static final String CONTAINER_REGEX_64 = "[0-9a-fA-F]{64}";
+    private static final String CONTAINER_UID_REGEX = "^" + CONTAINER_REGEX_64 + "$";
     private static final String SHORTENED_UUID_PATTERN = "^[0-9a-fA-F]{8}\\-[0-9a-fA-F]{4}\\-[0-9a-fA-F]{4}\\-[0-9a-fA-F]{4}\\-[0-9a-fA-F]{4,}";
     private static final String AWS_FARGATE_UID_REGEX = "^[0-9a-fA-F]{32}\\-[0-9]{10}$";
     private static final String POD_REGEX = "(?:^/kubepods[\\S]*/pod([^/]+)$)|(?:kubepods[^/]*-pod([^/]+)\\.slice)";
 
+    private static final String CGROUPV2_HOSTNAME_FILE = "/etc/hostname";
+    private static final Pattern CGROUPV2_CONTAINER_PATTERN = Pattern.compile("^.*(" + CONTAINER_REGEX_64 + ").*$");
+
+    private static final String SELF_CGROUP = "/proc/self/cgroup";
+    private static final String SELF_MOUNTINFO = "/proc/self/mountinfo";
+
     /**
      * Architecture of the system the agent is running on.
      */
@@ -56,6 +63,7 @@ public class SystemInfo {
     /**
      * Hostname configured manually through {@link co.elastic.apm.agent.configuration.CoreConfiguration#hostname}.
      */
+    @SuppressWarnings("JavadocReference")
     @Nullable
     private final String configuredHostname;
 
@@ -99,11 +107,13 @@ public SystemInfo(String architecture, @Nullable String configuredHostname, @Nul
     /**
      * Creates a {@link SystemInfo} containing auto-discovered info about the system.
      * This method may block on reading files and executing external processes.
-     * @param configuredHostname hostname configured through the {@link co.elastic.apm.agent.configuration.CoreConfiguration#hostname} config
-     * @param timeoutMillis enables to limit the execution of the system discovery task
+     *
+     * @param configuredHostname      hostname configured through the {@link co.elastic.apm.agent.configuration.CoreConfiguration#hostname} config
+     * @param timeoutMillis           enables to limit the execution of the system discovery task
      * @param serverlessConfiguration serverless config
      * @return a future from which this system's info can be obtained
      */
+    @SuppressWarnings("JavadocReference")
     public static SystemInfo create(final @Nullable String configuredHostname, final long timeoutMillis, ServerlessConfiguration serverlessConfiguration) {
         final String osName = System.getProperty("os.name");
         final String osArch = System.getProperty("os.arch");
@@ -134,7 +144,8 @@ static boolean isWindows(String osName) {
      * Discover the current host's name. This method separates operating systems only to Windows and non-Windows,
      * both in the executed hostname-discovery-command and the fallback environment variables.
      * It always starts with execution of a command on an external process, so it may block up to the specified timeout.
-     * @param isWindows used to decide how hostname discovery should be executed
+     *
+     * @param isWindows     used to decide how hostname discovery should be executed
      * @param timeoutMillis limits the time this method may block on executing external commands
      * @return the discovered hostname
      */
@@ -193,7 +204,8 @@ static String discoverHostnameThroughCommand(boolean isWindows, long timeoutMill
     /**
      * Tries to discover the current host name by executing the provided command in a spawned process.
      * This method may block up to the specified timeout, waiting for the spawned process to terminate.
-     * @param cmd the hostname discovery command
+     *
+     * @param cmd           the hostname discovery command
      * @param timeoutMillis maximum time to allow to the provided command to execute
      * @return the discovered hostname
      */
@@ -259,21 +271,9 @@ static String removeDomain(String hostname) {
      * @return container ID parsed from {@code /proc/self/cgroup} file lines, or {@code null} if can't find/read/parse file lines
      */
     SystemInfo findContainerDetails() {
-        String containerId = null;
-        try {
-            Path path = FileSystems.getDefault().getPath("/proc/self/cgroup");
-            if (path.toFile().exists()) {
-                List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
-                for (final String line : lines) {
-                    parseContainerId(line);
-                    if (container != null) {
-                        containerId = container.getId();
-                        break;
-                    }
-                }
-            }
-        } catch (Throwable e) {
-            logger.warn("Failed to read/parse container ID from '/proc/self/cgroup'", e);
+        parseCgroupsFile(FileSystems.getDefault().getPath(SELF_CGROUP));
+        if (container == null) {
+            parseMountInfo(FileSystems.getDefault().getPath(SELF_MOUNTINFO));
         }
 
         try {
@@ -297,29 +297,68 @@ SystemInfo findContainerDetails() {
             logger.warn("Failed to read environment variables for Kubernetes Downward API discovery", e);
         }
 
-        logger.debug("container ID is {}", containerId);
+        logger.debug("container ID is {}", container != null ? container.getId() : null);
         return this;
     }
 
+    @Nullable
+    private void parseMountInfo(Path path) {
+        if (!Files.isRegularFile(path)) {
+            logger.debug("Could not parse container ID from '{}'", path);
+            return;
+        }
+        try {
+            List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
+            parseCgroupsV2ContainerId(lines);
+            if (container != null) {
+                return;
+            }
+            logger.debug("Could not parse container ID from '{}' lines: {}", path, lines);
+        } catch (Throwable e) {
+            logger.warn(String.format("Failed to read/parse container ID from '%s'", path), e);
+        }
+    }
+
+    @Nullable
+    private void parseCgroupsFile(Path path) {
+        if(!Files.isRegularFile(path)){
+            logger.debug("Could not parse container ID from '{}'", path);
+            return;
+        }
+        try {
+            List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
+            for (String line : lines) {
+                parseCgroupsLine(line);
+                if (container != null) {
+                    return;
+                }
+            }
+        } catch (Throwable e) {
+            logger.warn(String.format("Failed to read/parse container ID from '%s'", path), e);
+        }
+    }
+
     /**
      * The virtual file /proc/self/cgroup lists the control groups that the process is a member of. Each line contains
      * three colon-separated fields of the form hierarchy-ID:subsystem-list:cgroup-path.
-     *
+     * <p>
      * Depending on the filesystem driver used for cgroup management, the cgroup-path will have
      * one of the following formats in a Docker container:
-     *
-     * 		systemd: /system.slice/docker-<container-ID>.scope
-     * 		cgroupfs: /docker/<container-ID>
-     *
-     * 	In a Kubernetes pod, the cgroup path will look like:
-     *
-     * 		systemd: /kubepods.slice/kubepods-<QoS-class>.slice/kubepods-<QoS-class>-pod<pod-UID>.slice/<container-iD>.scope
-     * 		cgroupfs: /kubepods/<QoS-class>/pod<pod-UID>/<container-iD>
+     * </p>
+     * <pre>
+     *   systemd: /system.slice/docker-<container-ID>.scope
+     *   cgroupfs: /docker/<container-ID>
+     * </pre>
+     * In a Kubernetes pod, the cgroup path will look like:
+     * <pre>
+     *   systemd: /kubepods.slice/kubepods-<QoS-class>.slice/kubepods-<QoS-class>-pod<pod-UID>.slice/<container-iD>.scope
+     *   cgroupfs: /kubepods/<QoS-class>/pod<pod-UID>/<container-iD>
+     * </pre
      *
      * @param line a line from the /proc/self/cgroup file
      * @return this SystemInfo object after parsing
      */
-    SystemInfo parseContainerId(String line) {
+    SystemInfo parseCgroupsLine(String line) {
         final String[] fields = line.split(":", 3);
         if (fields.length == 3) {
             String cGroupPath = fields[2];
@@ -364,14 +403,38 @@ SystemInfo parseContainerId(String line) {
                 if (kubernetes != null ||
                     idPart.matches(CONTAINER_UID_REGEX) ||
                     idPart.matches(SHORTENED_UUID_PATTERN) ||
-                    idPart.matches(AWS_FARGATE_UID_REGEX))  {
+                    idPart.matches(AWS_FARGATE_UID_REGEX)) {
                     container = new Container(idPart);
                 }
             }
         }
         if (container == null) {
-            logger.debug("Could not parse container ID from '/proc/self/cgroup' line: {}", line);
+            logger.debug("Could not parse container ID from line: {}", line);
+        }
+        return this;
+    }
+
+    /**
+     * @param lines lines from the /proc/self/mountinfo file
+     * @return this SystemInfo object after parsing
+     */
+    SystemInfo parseCgroupsV2ContainerId(List<String> lines) {
+        for (String line : lines) {
+            int index = line.indexOf(CGROUPV2_HOSTNAME_FILE);
+            if (index > 0) {
+                String[] parts = line.split(" ");
+                if (parts.length > 3) {
+                    Matcher matcher = CGROUPV2_CONTAINER_PATTERN.matcher(parts[3]);
+                    if (matcher.matches() && matcher.groupCount() == 1) {
+                        container = new Container(matcher.group(1));
+                    }
+                }
+            }
         }
+
+
+
+
         return this;
     }
 
@@ -386,23 +449,26 @@ public String getArchitecture() {
      * Returns the hostname. If a non-empty hostname was configured manually, it will be returned.
      * Otherwise, the automatically discovered hostname will be returned.
      * If both are null or empty, this method returns {@code <unknown>}.
+     *
      * @deprecated should only be used when communicating to APM Server of version lower than 7.4
      */
-     @Deprecated
+    @Deprecated
     public String getHostname() {
-         if (configuredHostname != null && !configuredHostname.isEmpty()) {
-             return configuredHostname;
-         }
-         if (detectedHostname != null && !detectedHostname.isEmpty()) {
-             return detectedHostname;
-         }
-         return "<unknown>";
+        if (configuredHostname != null && !configuredHostname.isEmpty()) {
+            return configuredHostname;
+        }
+        if (detectedHostname != null && !detectedHostname.isEmpty()) {
+            return detectedHostname;
+        }
+        return "<unknown>";
     }
 
     /**
      * The hostname manually configured through {@link co.elastic.apm.agent.configuration.CoreConfiguration#hostname}
+     *
      * @return the manually configured hostname
      */
+    @SuppressWarnings("JavadocReference")
     @Nullable
     public String getConfiguredHostname() {
         return configuredHostname;
@@ -444,7 +510,7 @@ public Kubernetes getKubernetesInfo() {
     }
 
     public static class Container {
-        private String id;
+        private final String id;
 
         Container(String id) {
             this.id = id;

apm-agent-core/src/test/java/co/elastic/apm/agent/impl/metadata/ContainerInfoTest.java

@@ -41,8 +41,8 @@ public class ContainerInfoTest extends CustomEnvVariables {
 
     @ParameterizedTest(name = "{0}")
     @MethodSource("getCommonPatterns")
-    void testCommonPatterns(String testName, String groupLine, @Nullable String containerId, @Nullable String podId) {
-        SystemInfo systemInfo = createSystemInfo().parseContainerId(groupLine);
+    void testCommonPatternsCgroupsV1(String testName, String groupLine, @Nullable String containerId, @Nullable String podId) {
+        SystemInfo systemInfo = createSystemInfo().parseCgroupsLine(groupLine);
         assertThat(systemInfo).isNotNull();
         SystemInfo.Container containerInfo = systemInfo.getContainerInfo();
         if (containerId == null) {
@@ -83,6 +83,29 @@ static Stream<Arguments> getCommonPatterns() {
         return args.stream();
     }
 
+    @Test
+    void testCgroupsV2() {
+        JsonNode json = TestJsonSpec.getJson("mounts_parsing.json");
+        assertThat(json.isObject())
+            .describedAs("unexpected JSON spec format")
+            .isTrue();
+
+        JsonNode jsonLines = json.get("lines");
+        assertThat(jsonLines.isArray()).isTrue();
+        List<String> lines = new ArrayList<>();
+        for (int i = 0; i < jsonLines.size(); i++) {
+            lines.add(jsonLines.get(i).asText());
+        }
+        JsonNode jsonContainerId = json.get("containerId");
+        assertThat(jsonContainerId.isTextual()).isTrue();
+        String expectedContainerId = jsonContainerId.asText();
+
+        SystemInfo systemInfo = createSystemInfo().parseCgroupsV2ContainerId(lines);
+        assertThat(systemInfo).isNotNull();
+        assertThat(systemInfo.getContainerInfo()).describedAs("missing container info").isNotNull();
+        assertThat(systemInfo.getContainerInfo().getId()).isEqualTo(expectedContainerId);
+    }
+
     @Test
     void testContainerIdParsing() {
         String validId = "3741401135a8d27237e2fb9c0fb2ecd93922c0d1dd708345451e479613f8d4ae";
@@ -168,7 +191,7 @@ void testKubernetesInfo() {
     void testUbuntuCgroup() {
         String line = "1:name=systemd:/user.slice/user-1000.slice/[email protected]/apps.slice/apps-org.gnome.Terminal" +
             ".slice/vte-spawn-75bc72bd-6642-4cf5-b62c-0674e11bfc84.scope";
-        assertThat(createSystemInfo().parseContainerId(line).getContainerInfo()).isNull();
+        assertThat(createSystemInfo().parseCgroupsLine(line).getContainerInfo()).isNull();
     }
 
     @Test
@@ -237,15 +260,15 @@ private SystemInfo createSystemInfo() {
 
     private SystemInfo assertContainerId(String line, String containerId) {
         SystemInfo systemInfo = createSystemInfo();
-        assertThat(systemInfo.parseContainerId(line).getContainerInfo()).isNotNull();
+        assertThat(systemInfo.parseCgroupsLine(line).getContainerInfo()).isNotNull();
         //noinspection ConstantConditions
         assertThat(systemInfo.getContainerInfo().getId()).isEqualTo(containerId);
         return systemInfo;
     }
 
     private void assertContainerInfoIsNull(String line) {
         SystemInfo systemInfo = createSystemInfo();
-        assertThat(systemInfo.parseContainerId(line).getContainerInfo()).isNull();
+        assertThat(systemInfo.parseCgroupsLine(line).getContainerInfo()).isNull();
     }
 
     private void assertKubernetesInfo(SystemInfo systemInfo, @Nullable String podUid, @Nullable String podName, @Nullable String nodeName,

apm-agent-core/src/test/resources/json-specs/mounts_parsing.json

@@ -0,0 +1,20 @@
+{
+  "lines": [
+    "3984 3905 0:73 / / rw,relatime shared:1863 master:1733 - overlay overlay rw,lowerdir=/var/lib/docker/overlay2/l/KEX7CWLHQCXQY2RHPGTXJ3C26N:/var/lib/docker/overlay2/l/2PVS7JRTRSTVZS4KSUAFML3BIV:/var/lib/docker/overlay2/l/52M7ARM4JDVHCJAYUI6JIKBO4B,upperdir=/var/lib/docker/overlay2/267f825fb89e584605bf161177451879c0ba8b15f7df9b51fb7843c7beb9ed25/diff,workdir=/var/lib/docker/overlay2/267f825fb89e584605bf161177451879c0ba8b15f7df9b51fb7843c7beb9ed25/work",
+    "3985 3984 0:77 / /proc rw,nosuid,nodev,noexec,relatime shared:1864 - proc proc rw",
+    "3986 3984 0:78 / /dev rw,nosuid shared:1865 - tmpfs tmpfs rw,size=65536k,mode=755,inode64",
+    "3987 3986 0:79 / /dev/pts rw,nosuid,noexec,relatime shared:1866 - devpts devpts rw,gid=5,mode=620,ptmxmode=666",
+    "3988 3984 0:80 / /sys ro,nosuid,nodev,noexec,relatime shared:1870 - sysfs sysfs ro",
+    "3989 3988 0:30 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime shared:1871 - cgroup2 cgroup rw",
+    "3990 3986 0:76 / /dev/mqueue rw,nosuid,nodev,noexec,relatime shared:1867 - mqueue mqueue rw",
+    "3991 3986 0:81 / /dev/shm rw,nosuid,nodev,noexec,relatime shared:1868 - tmpfs shm rw,size=65536k,inode64",
+    "3992 3984 253:1 /var/lib/docker/volumes/9d18ce5b36572d85358fa936afe5a4bf95cca5c822b04941aa08c6118f6e0d33/_data /var rw,relatime shared:1872 master:1 - ext4 /dev/mapper/vgubuntu-root rw,errors=remount-ro",
+    "3993 3984 0:82 / /run rw,nosuid,nodev,noexec,relatime shared:1873 - tmpfs tmpfs rw,inode64",
+    "3994 3984 0:83 / /tmp rw,nosuid,nodev,noexec,relatime shared:1874 - tmpfs tmpfs rw,inode64",
+    "3995 3984 253:1 /usr/lib/modules /usr/lib/modules ro,relatime shared:1875 - ext4 /dev/mapper/vgubuntu-root rw,errors=remount-ro",
+    "3996 3984 253:1 /var/lib/docker/containers/6548c6863fb748e72d1e2a4f824fde92f720952d062dede1318c2d6219a672d6/resolv.conf /etc/resolv.conf rw,relatime shared:1876 - ext4 /dev/mapper/vgubuntu-root rw,errors=remount-ro",
+    "3997 3984 253:1 /var/lib/docker/containers/6548c6863fb748e72d1e2a4f824fde92f720952d062dede1318c2d6219a672d6/hostname /etc/hostname rw,relatime shared:1877 - ext4 /dev/mapper/vgubuntu-root rw,errors=remount-ro",
+    "3998 3984 253:1 /var/lib/docker/containers/6548c6863fb748e72d1e2a4f824fde92f720952d062dede1318c2d6219a672d6/hosts /etc/hosts rw,relatime shared:1878 - ext4 /dev/mapper/vgubuntu-root rw,errors=remount-ro"
+  ],
+  "containerId": "6548c6863fb748e72d1e2a4f824fde92f720952d062dede1318c2d6219a672d6"
+}