[main] [ML] Use latest results index for new Anomaly Detection jobs (#122597) (#122673)

* [ML] Use latest results index for new Anomaly Detection jobs (#122597)

After upgrading from v7 new anomaly detection jobs should 
use the latest results index if one has been created.

* Delete 8.x test

Author: davidkyle

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/persistence/JobResultsProvider.java

@@ -125,6 +125,7 @@
 import org.elasticsearch.xpack.core.ml.stats.ForecastStats;
 import org.elasticsearch.xpack.core.ml.stats.StatsAccumulator;
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
+import org.elasticsearch.xpack.core.ml.utils.MlIndexAndAlias;
 import org.elasticsearch.xpack.core.security.support.Exceptions;
 import org.elasticsearch.xpack.ml.MachineLearning;
 import org.elasticsearch.xpack.ml.job.categorization.GrokPatternCreator;
@@ -306,11 +307,15 @@ public void createJobResultIndex(Job job, ClusterState state, final ActionListen
         String readAliasName = AnomalyDetectorsIndex.jobResultsAliasedName(job.getId());
         String writeAliasName = AnomalyDetectorsIndex.resultsWriteAlias(job.getId());
         String tempIndexName = job.getInitialResultsIndexName();
+        // Find all indices starting with this name and pick the latest one
+        String[] concreteIndices = resolver.concreteIndexNames(state, IndicesOptions.lenientExpandOpen(), tempIndexName + "*");
+        if (concreteIndices.length > 0) {
+            tempIndexName = MlIndexAndAlias.latestIndex(concreteIndices);
+        }
 
         // Our read/write aliases should point to the concrete index
         // If the initial index is NOT an alias, either it is already a concrete index, or it does not exist yet
         if (state.getMetadata().getProject().hasAlias(tempIndexName)) {
-            String[] concreteIndices = resolver.concreteIndexNames(state, IndicesOptions.lenientExpandOpen(), tempIndexName);
 
             // SHOULD NOT be closed as in typical call flow checkForLeftOverDocuments already verified this
             // if it is closed, we bailout and return an error
@@ -324,8 +329,8 @@ public void createJobResultIndex(Job job, ClusterState state, final ActionListen
                 );
                 return;
             }
-            tempIndexName = concreteIndices[0];
         }
+
         final String indexName = tempIndexName;
 
         ActionListener<Boolean> indexAndMappingsListener = ActionListener.wrap(success -> {

x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/MlJobSnapshotUpgradeIT.java

@@ -279,7 +279,7 @@ private Response buildAndPutJob(String jobId, TimeValue bucketSpan) throws Excep
         return client().performRequest(request);
     }
 
-    private static List<String> generateData(
+    static List<String> generateData(
         long timestamp,
         TimeValue bucketSpan,
         int bucketCount,

x-pack/qa/src/main/java/org/elasticsearch/xpack/test/rest/XPackRestTestConstants.java

@@ -17,20 +17,15 @@ public final class XPackRestTestConstants {
     public static final String[] TEMPLATE_NAMES_NO_ILM = new String[] { HISTORY_TEMPLATE_NAME_NO_ILM };
 
     // ML constants:
-    public static final String ML_META_INDEX_NAME = ".ml-meta";
-    public static final String CONFIG_INDEX = ".ml-config";
     public static final String RESULTS_INDEX_PREFIX = ".ml-anomalies-";
     public static final String STATE_INDEX_PREFIX = ".ml-state";
-    public static final String RESULTS_INDEX_DEFAULT = "shared";
 
     public static final List<String> ML_POST_V7120_TEMPLATES = List.of(STATE_INDEX_PREFIX, RESULTS_INDEX_PREFIX);
 
     // Transform constants:
     public static final String TRANSFORM_TASK_NAME = "data_frame/transforms";
     public static final String TRANSFORM_INTERNAL_INDEX_PREFIX = ".transform-internal-";
-    public static final String TRANSFORM_NOTIFICATIONS_INDEX_PREFIX = ".transform-notifications-";
     public static final String TRANSFORM_INTERNAL_INDEX_PREFIX_DEPRECATED = ".data-frame-internal-";
-    public static final String TRANSFORM_NOTIFICATIONS_INDEX_PREFIX_DEPRECATED = ".data-frame-notifications-";
 
     private XPackRestTestConstants() {}
 }