Shrink request to throw IllegalArgumentException when index not write blocked

CHANGELOG.md

@@ -40,6 +40,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Optimized date histogram aggregations by preventing unnecessary object allocations in date rounding utils ([19088](https://github.com/opensearch-project/OpenSearch/pull/19088))
 - Optimize source conversion in gRPC search hits using zero-copy BytesRef ([#19280](https://github.com/opensearch-project/OpenSearch/pull/19280))
 - Add failureaccess as runtime dependency to transport-grpc module  ([#19339](https://github.com/opensearch-project/OpenSearch/pull/19339))
+- Change shrink request to throw IllegalArgumentException when index not write blocked ([#19414](https://github.com/opensearch-project/OpenSearch/pull/19414))
 
 ### Fixed
 - Fix unnecessary refreshes on update preparation failures ([#15261](https://github.com/opensearch-project/OpenSearch/issues/15261))

rest-api-spec/src/main/resources/rest-api-spec/test/indices.shrink/10_basic.yml

@@ -33,6 +33,20 @@ setup:
   - skip:
       features: allowed_warnings
 
+ # try shrink without making it read only
+  - do:
+      catch: /action_request_validation_exception/
+      indices.shrink:
+        index: source
+        target: "new_shrunken_index"
+        wait_for_active_shards: 1
+        cluster_manager_timeout: 10s
+        body:
+          settings:
+            index.number_of_replicas: 0
+            index.number_of_shards: 1
+            index.blocks.read_only: true
+
   # make it read-only
   - do:
       indices.put_settings:
@@ -45,7 +59,6 @@ setup:
       cluster.health:
         wait_for_status: green
         index: source
-
   # now we do the actual shrink
   - do:
       allowed_warnings:

server/src/main/java/org/opensearch/cluster/metadata/MetadataCreateIndexService.java

@@ -1652,7 +1652,7 @@ static IndexMetadata validateResize(ClusterState state, String sourceIndex, Stri
 
         // ensure write operations on the source index is blocked
         if (state.blocks().indexBlocked(ClusterBlockLevel.WRITE, sourceIndex) == false) {
-            throw new IllegalStateException(
+            throw new IllegalArgumentException(
                 "index " + sourceIndex + " must block write operations to resize index. use \"index.blocks.write=true\""
             );
         }

server/src/test/java/org/opensearch/cluster/metadata/MetadataCreateIndexServiceTests.java

@@ -341,7 +341,7 @@ public void testValidateShrinkIndex() {
         assertEquals(
             "index source must block write operations to resize index. use \"index.blocks.write=true\"",
             expectThrows(
-                IllegalStateException.class,
+                IllegalArgumentException.class,
                 () -> MetadataCreateIndexService.validateShrinkIndex(
                     createClusterState("source", randomIntBetween(2, 100), randomIntBetween(0, 10), Settings.EMPTY),
                     "source",
@@ -443,7 +443,7 @@ public void testValidateSplitIndex() {
         assertEquals(
             "index source must block write operations to resize index. use \"index.blocks.write=true\"",
             expectThrows(
-                IllegalStateException.class,
+                IllegalArgumentException.class,
                 () -> MetadataCreateIndexService.validateSplitIndex(
                     createClusterState("source", randomIntBetween(2, 100), randomIntBetween(0, 10), Settings.EMPTY),
                     "source",
@@ -529,7 +529,7 @@ public void testValidateCloneIndex() {
         assertEquals(
             "index source must block write operations to resize index. use \"index.blocks.write=true\"",
             expectThrows(
-                IllegalStateException.class,
+                IllegalArgumentException.class,
                 () -> MetadataCreateIndexService.validateCloneIndex(
                     createClusterState("source", randomIntBetween(2, 100), randomIntBetween(0, 10), Settings.EMPTY),
                     "source",