Fix constraint bug which allows more primary shards than average prim…

…ary shards per index (opensearch-project#14908) (opensearch-project#14916)

(cherry picked from commit 3497081)

Signed-off-by: Gaurav Bafna <gbbafna@amazon.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

server/src/main/java/org/opensearch/cluster/routing/allocation/ConstraintTypes.java

@@ -70,7 +70,7 @@ public static Predicate<Constraint.ConstraintParams> isPerIndexPrimaryShardsPerN
         return (params) -> {
             int perIndexPrimaryShardCount = params.getNode().numPrimaryShards(params.getIndex());
             int perIndexAllowedPrimaryShardCount = (int) Math.ceil(params.getBalancer().avgPrimaryShardsPerNode(params.getIndex()));
-            return perIndexPrimaryShardCount > perIndexAllowedPrimaryShardCount;
+            return perIndexPrimaryShardCount >= perIndexAllowedPrimaryShardCount;
         };
     }
 

server/src/test/java/org/opensearch/cluster/routing/allocation/AllocationConstraintsTests.java

@@ -93,7 +93,7 @@ public void testPerIndexPrimaryShardsConstraint() {
 
         assertEquals(0, constraints.weight(balancer, node, indexName));
 
-        perIndexPrimaryShardCount = 3;
+        perIndexPrimaryShardCount = 2;
         when(node.numPrimaryShards(anyString())).thenReturn(perIndexPrimaryShardCount);
         assertEquals(CONSTRAINT_WEIGHT, constraints.weight(balancer, node, indexName));