Extend the selective muting of memory tests on Debian 8 (#67456)

The selective muting implemented for autoscaling in #67159
is extended to the ML tests that also fail when machine
memory is reported as 0.

Most of the logic to determine when memory will not be
accurately reported is now in a utility method in the
base class.

Relates #66885
Backport of #67422

Author: droberts195

test/framework/src/main/java/org/elasticsearch/test/ESIntegTestCase.java

@@ -57,6 +57,7 @@
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.support.DefaultShardOperationFailedException;
 import org.elasticsearch.action.support.IndicesOptions;
+import org.elasticsearch.bootstrap.JavaVersion;
 import org.elasticsearch.client.AdminClient;
 import org.elasticsearch.client.Client;
 import org.elasticsearch.client.Requests;
@@ -2350,4 +2351,22 @@ public static Index resolveIndex(String index) {
     public static boolean inFipsJvm() {
         return Security.getProviders()[0].getName().toLowerCase(Locale.ROOT).contains("fips");
     }
+
+    /**
+     * On Debian 8 the "memory" subsystem is not mounted by default
+     * when cgroups are enabled, and this confuses many versions of
+     * Java prior to Java 15.  Tests that rely on machine memory
+     * being accurately determined will not work on such setups,
+     * and can use this method for selective muting.
+     * See https://github.com/elastic/elasticsearch/issues/67089
+     * and https://github.com/elastic/elasticsearch/issues/66885
+     */
+    protected boolean willSufferDebian8MemoryProblem() {
+        final NodesInfoResponse response = client().admin().cluster().prepareNodesInfo().execute().actionGet();
+        final boolean anyDebian8Nodes = response.getNodes()
+            .stream()
+            .anyMatch(ni -> ni.getOs().getPrettyName().equals("Debian GNU/Linux 8 (jessie)"));
+        boolean java15Plus = JavaVersion.current().compareTo(JavaVersion.parse("15")) >= 0;
+        return anyDebian8Nodes && java15Plus == false;
+    }
 }

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/integration/MlDistributedFailureIT.java

@@ -337,6 +337,9 @@ public void testStopAndForceStopDatafeed() throws Exception {
 
     public void testJobRelocationIsMemoryAware() throws Exception {
 
+        // see: https://github.com/elastic/elasticsearch/issues/66885#issuecomment-758790179
+        assumeFalse("cannot run on debian 8 prior to java 15", willSufferDebian8MemoryProblem());
+
         internalCluster().ensureAtLeastNumDataNodes(1);
         ensureStableClusterOnAllNodes(1);
 

x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/integration/TooManyJobsIT.java

@@ -124,10 +124,14 @@ public void testLazyNodeValidation() throws Exception {
     }
 
     public void testSingleNode() throws Exception {
+        // see: https://github.com/elastic/elasticsearch/issues/66885#issuecomment-758790179
+        assumeFalse("cannot run on debian 8 prior to java 15", willSufferDebian8MemoryProblem());
         verifyMaxNumberOfJobsLimit(1, randomIntBetween(1, 20));
     }
 
     public void testMultipleNodes() throws Exception {
+        // see: https://github.com/elastic/elasticsearch/issues/66885#issuecomment-758790179
+        assumeFalse("cannot run on debian 8 prior to java 15", willSufferDebian8MemoryProblem());
         verifyMaxNumberOfJobsLimit(3, randomIntBetween(1, 20));
     }