8261242: [Linux] OSContainer::is_containerized() returns true when run outside a container

Reviewed-by: stuefe, iklam

src/java.base/linux/classes/jdk/internal/platform/CgroupMetrics.java

@@ -35,6 +35,11 @@ public class CgroupMetrics implements Metrics {
         this.subsystem = Objects.requireNonNull(subsystem);
     }
 
+    @Override
+    public boolean isContainerized() {
+        return isContainerized0();
+    }
+
     @Override
     public String getProvider() {
         return subsystem.getProvider();
@@ -194,6 +199,7 @@ public class CgroupMetrics implements Metrics {
     }
 
     private static native boolean isUseContainerSupport();
+    private static native boolean isContainerized0();
     private static native long getTotalMemorySize0();
     private static native long getTotalSwapSize0();
 

src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystem.java

@@ -31,6 +31,11 @@ package jdk.internal.platform;
  */
 public interface CgroupSubsystem extends Metrics {
 
+
+    default boolean isContainerized() {
+        return false; // This default impl is never used
+    }
+
     /**
      * Returned for metrics of type long if the underlying implementation
      * has determined that no limit is being imposed.

src/java.base/linux/native/libjava/CgroupMetrics.c

@@ -36,6 +36,12 @@ Java_jdk_internal_platform_CgroupMetrics_isUseContainerSupport(JNIEnv *env, jcla
     return JVM_IsUseContainerSupport();
 }
 
+JNIEXPORT jboolean JNICALL
+Java_jdk_internal_platform_CgroupMetrics_isContainerized0(JNIEnv *env, jclass ignored)
+{
+    return JVM_IsContainerized();
+}
+
 JNIEXPORT jlong JNICALL
 Java_jdk_internal_platform_CgroupMetrics_getTotalMemorySize0
   (JNIEnv *env, jclass ignored)

src/java.base/share/classes/jdk/internal/platform/Metrics.java

@@ -71,6 +71,23 @@ public interface Metrics {
      */
     public String getProvider();
 
+    /**
+     * Determines whether or not the underlying system
+     * has useful metrics (a.k.a. is containerized).
+     *
+     * @implNote
+     * Note that Metrics on some systems aren't useful.
+     * For example on a regular Linux system with cgroups
+     * present, with no limits enforced and not running in
+     * a container, Metric aren't useful. This can be used
+     * in order to determine if the system is containerized.
+     *
+     * @return true when the JVM runs in containerized mode.
+     *         false otherwise.
+     *
+     */
+    public boolean isContainerized();
+
 
     /* ***************************************************************
      * CPU Accounting Subsystem

src/java.base/share/classes/sun/launcher/LauncherHelper.java

@@ -370,6 +370,10 @@ public final class LauncherHelper {
         final long longRetvalNotSupported = -2;
 
         ostream.println(INDENT + "Provider: " + c.getProvider());
+        if (!c.isContainerized()) {
+            ostream.println(INDENT + "System not containerized.");
+            return;
+        }
         ostream.println(INDENT + "Effective CPU Count: " + c.getEffectiveCpuCount());
         ostream.println(formatCpuVal(c.getCpuPeriod(), INDENT + "CPU Period: ", longRetvalNotSupported));
         ostream.println(formatCpuVal(c.getCpuQuota(), INDENT + "CPU Quota: ", longRetvalNotSupported));