Add limit on number of processors in Ingest pipelines

Signed-off-by: Rai <nndri@amazon.com>

CHANGELOG.md

@@ -28,6 +28,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add support for index level max slice count setting for concurrent segment search ([#15336](https://github.com/opensearch-project/OpenSearch/pull/15336))
 - Add support for centralize snapshot creation with pinned timestamp ([#15124](https://github.com/opensearch-project/OpenSearch/pull/15124))
 - Add concurrent search support for Derived Fields ([#15326](https://github.com/opensearch-project/OpenSearch/pull/15326))
+- Add limit on number of processors in Ingest pipelines([#15460](https://github.com/opensearch-project/OpenSearch/issues/15460)).
 
 ### Dependencies
 - Bump `netty` from 4.1.111.Final to 4.1.112.Final ([#15081](https://github.com/opensearch-project/OpenSearch/pull/15081))

server/src/main/java/org/opensearch/action/ingest/SimulateExecutionService.java

@@ -91,6 +91,7 @@ void executeDocument(
     }
 
     public void execute(SimulatePipelineRequest.Parsed request, ActionListener<SimulatePipelineResponse> listener) {
+
         threadPool.executor(THREAD_POOL_NAME).execute(ActionRunnable.wrap(listener, l -> {
             final AtomicInteger counter = new AtomicInteger();
             final List<SimulateDocumentResult> responses = new CopyOnWriteArrayList<>(

server/src/main/java/org/opensearch/action/ingest/SimulatePipelineTransportAction.java

@@ -38,6 +38,7 @@
 import org.opensearch.common.xcontent.XContentHelper;
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.common.io.stream.Writeable;
+import org.opensearch.ingest.IngestPipelineValidator;
 import org.opensearch.ingest.IngestService;
 import org.opensearch.tasks.Task;
 import org.opensearch.threadpool.ThreadPool;
@@ -88,6 +89,8 @@ protected void doExecute(Task task, SimulatePipelineRequest request, ActionListe
             return;
         }
 
+        IngestPipelineValidator.validateIngestPipeline(simulateRequest.getPipeline(), ingestService.getClusterService());
+
         executionService.execute(simulateRequest, listener);
     }
 }

server/src/main/java/org/opensearch/common/settings/ClusterSettings.java

@@ -132,6 +132,7 @@
 import org.opensearch.indices.fielddata.cache.IndicesFieldDataCache;
 import org.opensearch.indices.recovery.RecoverySettings;
 import org.opensearch.indices.store.IndicesStore;
+import org.opensearch.ingest.IngestPipelineValidator;
 import org.opensearch.monitor.fs.FsHealthService;
 import org.opensearch.monitor.fs.FsService;
 import org.opensearch.monitor.jvm.JvmGcMonitorService;
@@ -405,6 +406,7 @@ public void apply(Settings value, Settings current, Settings previous) {
                 ClusterService.USER_DEFINED_METADATA,
                 ClusterManagerService.MASTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD_SETTING,  // deprecated
                 ClusterManagerService.CLUSTER_MANAGER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD_SETTING,
+                IngestPipelineValidator.MAX_NUMBER_OF_INGEST_PROCESSORS,
                 SearchService.DEFAULT_SEARCH_TIMEOUT_SETTING,
                 SearchService.DEFAULT_ALLOW_PARTIAL_SEARCH_RESULTS,
                 TransportSearchAction.SHARD_COUNT_LIMIT_SETTING,

server/src/main/java/org/opensearch/ingest/IngestPipelineValidator.java

@@ -0,0 +1,54 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.ingest;
+
+import org.opensearch.cluster.service.ClusterService;
+import org.opensearch.common.settings.Setting;
+
+import java.util.List;
+
+/**
+ * This class contains methods to validate the ingest pipeline.
+ */
+public class IngestPipelineValidator {
+
+    /**
+     * Defines the limit for the number of processors which can run on a given document during ingestion.
+     */
+    public static final Setting<Integer> MAX_NUMBER_OF_INGEST_PROCESSORS = Setting.intSetting(
+        "cluster.ingest.max_number_processors",
+        Integer.MAX_VALUE,
+        1,
+        Integer.MAX_VALUE,
+        Setting.Property.NodeScope,
+        Setting.Property.Dynamic
+    );
+
+    /**
+     * Validates that the number of compound processors in the pipeline does not exceed the configured limit.
+     *
+     * @param pipeline
+     * @param clusterService
+     */
+    public static void validateIngestPipeline(Pipeline pipeline, ClusterService clusterService) {
+
+        List<Processor> processors = pipeline.getCompoundProcessor().getProcessors();
+        int maxNumberOfIngestProcessorsAllowed = clusterService.getClusterSettings().get(MAX_NUMBER_OF_INGEST_PROCESSORS);
+
+        if (processors.size() > maxNumberOfIngestProcessorsAllowed) {
+            throw new IllegalStateException(
+                "Cannot use more than the maximum processors allowed. Number of processors configured is ["
+                    + processors.size()
+                    + "] which exceeds the maximum allowed configuration of ["
+                    + maxNumberOfIngestProcessorsAllowed
+                    + "] processors."
+            );
+        }
+    }
+}

server/src/main/java/org/opensearch/ingest/IngestService.java

@@ -494,6 +494,9 @@ void validatePipeline(Map<DiscoveryNode, IngestInfo> ingestInfos, PutPipelineReq
 
         Map<String, Object> pipelineConfig = XContentHelper.convertToMap(request.getSource(), false, request.getMediaType()).v2();
         Pipeline pipeline = Pipeline.create(request.getId(), pipelineConfig, processorFactories, scriptService);
+
+        IngestPipelineValidator.validateIngestPipeline(pipeline, clusterService);
+
         List<Exception> exceptions = new ArrayList<>();
         for (Processor processor : pipeline.flattenAllProcessors()) {
             for (Map.Entry<DiscoveryNode, IngestInfo> entry : ingestInfos.entrySet()) {
@@ -1099,6 +1102,7 @@ void innerUpdatePipelines(IngestMetadata newIngestMetadata) {
                     processorFactories,
                     scriptService
                 );
+                IngestPipelineValidator.validateIngestPipeline(newPipeline, clusterService);
                 newPipelines.put(newConfiguration.getId(), new PipelineHolder(newConfiguration, newPipeline));
 
                 if (previous == null) {

server/src/test/java/org/opensearch/cluster/service/ClusterServiceTests.java

@@ -10,6 +10,7 @@
 
 import org.opensearch.common.settings.ClusterSettings;
 import org.opensearch.common.settings.Settings;
+import org.opensearch.ingest.IngestPipelineValidator;
 import org.opensearch.test.OpenSearchTestCase;
 import org.opensearch.threadpool.TestThreadPool;
 import org.junit.After;
@@ -37,4 +38,16 @@ public void testDeprecatedGetMasterServiceBWC() {
             assertThat(masterService, equalTo(clusterManagerService));
         }
     }
+
+    public void testUpdateMaxIngestProcessorCountSetting() {
+        ClusterSettings clusterSettings = new ClusterSettings(Settings.builder().build(), ClusterSettings.BUILT_IN_CLUSTER_SETTINGS);
+
+        // verify defaults
+        assertEquals(Integer.MAX_VALUE, clusterSettings.get(IngestPipelineValidator.MAX_NUMBER_OF_INGEST_PROCESSORS).intValue());
+
+        // verify update max processor
+        Settings newSettings = Settings.builder().put("cluster.ingest.max_number_processors", 3).build();
+        clusterSettings.applySettings(newSettings);
+        assertEquals(3, clusterSettings.get(IngestPipelineValidator.MAX_NUMBER_OF_INGEST_PROCESSORS).intValue());
+    }
 }