Fix flaky SR test testStartReplicaAfterPrimaryIndexesDocs.

This test was failing because we are validating post recovery if a shard is able to perform segrep while also performing validation if a passed in checkopint.  In the post recovery test this checkpoint is always empty, yet the shard will be ahead of this checkpoint after docs are indexed.  This change differentiates shard validation from checkpoint validation.

Signed-off-by: Marc Handalian <handalm@amazon.com>

server/src/internalClusterTest/java/org/opensearch/indices/replication/SegmentReplicationIT.java

@@ -502,7 +502,6 @@ public void testCancellation() throws Exception {
         assertDocCounts(docCount, primaryNode);
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/opensearch-project/OpenSearch/issues/5669")
     public void testStartReplicaAfterPrimaryIndexesDocs() throws Exception {
         final String primaryNode = internalCluster().startNode(featureFlagSettings());
         createIndex(INDEX_NAME, Settings.builder().put(indexSettings()).put(IndexMetadata.SETTING_NUMBER_OF_REPLICAS, 0).build());

server/src/main/java/org/opensearch/index/shard/IndexShard.java

@@ -73,6 +73,7 @@
 import org.opensearch.cluster.routing.RecoverySource;
 import org.opensearch.cluster.routing.RecoverySource.SnapshotRecoverySource;
 import org.opensearch.cluster.routing.ShardRouting;
+import org.opensearch.cluster.routing.ShardRoutingState;
 import org.opensearch.common.Booleans;
 import org.opensearch.common.CheckedConsumer;
 import org.opensearch.common.CheckedFunction;
@@ -1438,15 +1439,13 @@ public ReplicationCheckpoint getLatestReplicationCheckpoint() {
         }
     }
 
+
     /**
-     * Checks if checkpoint should be processed
-     *
-     * @param requestCheckpoint       received checkpoint that is checked for processing
-     * @return true if checkpoint should be processed
+     * Checks if this shard is able to perform segment replication.
+     * @return - True if the shard is able to perform segment replication.
      */
-    public final boolean shouldProcessCheckpoint(ReplicationCheckpoint requestCheckpoint) {
-        if (state().equals(IndexShardState.STARTED) == false) {
-            logger.trace(() -> new ParameterizedMessage("Ignoring new replication checkpoint - shard is not started {}", state()));
+    public boolean isSegmentReplicationAllowed() {
+        if (indexSettings.isSegRepEnabled() == false) {
             return false;
         }
         if (getReplicationTracker().isPrimaryMode()) {
@@ -1457,6 +1456,27 @@ public final boolean shouldProcessCheckpoint(ReplicationCheckpoint requestCheckp
             logger.warn("Ignoring new replication checkpoint - primary shard cannot receive any checkpoints.");
             return false;
         }
+        if (state().equals(IndexShardState.STARTED) == false && (state() == IndexShardState.POST_RECOVERY && shardRouting.state() == ShardRoutingState.INITIALIZING) == false) {
+            logger.warn(() -> new ParameterizedMessage("Ignoring new replication checkpoint - shard is not started or recovering {} {}", state(), shardRouting.state()));
+            return false;
+        }
+        if (getReplicationEngine().isEmpty()) {
+            logger.warn(() -> new ParameterizedMessage("Ignoring checkpoint, attempting to perform segrep with wrong engine type {}", getEngine().getClass()));
+            return false;
+        }
+        return true;
+    }
+
+    /**
+     * Checks if checkpoint should be processed
+     *
+     * @param requestCheckpoint       received checkpoint that is checked for processing
+     * @return true if checkpoint should be processed
+     */
+    public final boolean shouldProcessCheckpoint(ReplicationCheckpoint requestCheckpoint) {
+        if (isSegmentReplicationAllowed() == false) {
+            return false;
+        }
         ReplicationCheckpoint localCheckpoint = getLatestReplicationCheckpoint();
         if (localCheckpoint.isAheadOf(requestCheckpoint)) {
             logger.trace(

server/src/main/java/org/opensearch/indices/cluster/IndicesClusterStateService.java

@@ -47,7 +47,6 @@
 import org.opensearch.cluster.node.DiscoveryNode;
 import org.opensearch.cluster.node.DiscoveryNodes;
 import org.opensearch.cluster.routing.ShardRouting;
-import org.opensearch.cluster.routing.ShardRoutingState;
 import org.opensearch.cluster.routing.RoutingTable;
 import org.opensearch.cluster.routing.IndexShardRoutingTable;
 import org.opensearch.cluster.routing.RoutingNode;
@@ -811,11 +810,7 @@ private void forceSegmentReplication(
         StepListener<Void> forceSegRepListener
     ) {
         IndexShard indexShard = (IndexShard) indexService.getShardOrNull(shardRouting.id());
-        if (indexShard != null
-            && indexShard.indexSettings().isSegRepEnabled()
-            && shardRouting.primary() == false
-            && shardRouting.state() == ShardRoutingState.INITIALIZING
-            && indexShard.state() == IndexShardState.POST_RECOVERY) {
+        if (indexShard != null && indexShard.isSegmentReplicationAllowed()) {
             segmentReplicationTargetService.startReplication(
                 ReplicationCheckpoint.empty(shardRouting.shardId()),
                 indexShard,

server/src/test/java/org/opensearch/index/shard/SegmentReplicationIndexShardTests.java

@@ -26,6 +26,7 @@
 import org.opensearch.index.IndexSettings;
 import org.opensearch.index.engine.DocIdSeqNoAndSource;
 import org.opensearch.index.engine.InternalEngine;
+import org.opensearch.index.engine.InternalEngineFactory;
 import org.opensearch.index.engine.NRTReplicationEngine;
 import org.opensearch.index.engine.NRTReplicationEngineFactory;
 import org.opensearch.index.mapper.MapperService;
@@ -90,6 +91,12 @@ public void testReplicationCheckpointNotNullForSegRep() throws IOException {
         closeShards(indexShard);
     }
 
+    public void testIsSegmentReplicationAllowed_WrongEngineType() throws IOException {
+        final IndexShard indexShard = newStartedShard(false, settings, new InternalEngineFactory());
+        assertFalse(indexShard.isSegmentReplicationAllowed());
+        closeShards(indexShard);
+    }
+
     public void testSegmentReplication_Index_Update_Delete() throws Exception {
         String mappings = "{ \"" + MapperService.SINGLE_MAPPING_NAME + "\": { \"properties\": { \"foo\": { \"type\": \"keyword\"} }}}";
         try (ReplicationGroup shards = createGroup(2, settings, mappings, new NRTReplicationEngineFactory())) {