[ML] Enrich documents with inference results at Fetch (#53230)

Adds a FetchSubPhase which adds a new field to the search hits with the result of the model 
inference performed on the hit. There isn't a direct way of configuring FetchSubPhases so 
SearchExtSpec is used for the purpose.

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/results/ClassificationInferenceResults.java

@@ -122,6 +122,24 @@ public void writeResult(IngestDocument document, String parentResultField) {
         }
     }
 
+    @Override
+    public Map<String, Object> writeResultToMap(String parentResultField) {
+        Map<String, Object> parentField = new HashMap<>();
+        Map<String, Object> results = new HashMap<>();
+        parentField.put(parentResultField, results);
+
+        results.put(resultsField, valueAsString());
+        if (topClasses.size() > 0) {
+            results.put(topNumClassesField, topClasses.stream().map(TopClassEntry::asValueMap).collect(Collectors.toList()));
+        }
+        if (getFeatureImportance().size() > 0) {
+            results.put("feature_importance", getFeatureImportance());
+        }
+
+        return parentField;
+    }
+
+
     @Override
     public String getWriteableName() {
         return NAME;

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/results/InferenceResults.java

@@ -8,8 +8,11 @@
 import org.elasticsearch.common.io.stream.NamedWriteable;
 import org.elasticsearch.ingest.IngestDocument;
 
+import java.util.Map;
+
 public interface InferenceResults extends NamedWriteable {
 
     void writeResult(IngestDocument document, String parentResultField);
 
+    Map<String, Object> writeResultToMap(String parentResultField);
 }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/results/RawInferenceResults.java

@@ -57,6 +57,11 @@ public void writeResult(IngestDocument document, String parentResultField) {
         throw new UnsupportedOperationException("[raw] does not support writing inference results");
     }
 
+    @Override
+    public Map<String, Object> writeResultToMap(String parentResultField) {
+        throw new UnsupportedOperationException("[raw] does not support writing inference results");
+    }
+
     @Override
     public String getWriteableName() {
         return NAME;

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/results/RegressionInferenceResults.java

@@ -14,6 +14,7 @@
 
 import java.io.IOException;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
 
@@ -74,6 +75,20 @@ public void writeResult(IngestDocument document, String parentResultField) {
         }
     }
 
+    @Override
+    public Map<String, Object> writeResultToMap(String parentResultField) {
+        Map<String, Object> parentResult = new HashMap<>();
+        Map<String, Object> result = new HashMap<>();
+        parentResult.put(parentResultField, result);
+
+        result.put(resultsField, value());
+        if (getFeatureImportance().size() > 0) {
+            result.put("feature_importance", getFeatureImportance());
+        }
+
+        return parentResult;
+    }
+
     @Override
     public String getWriteableName() {
         return NAME;

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/results/WarningInferenceResults.java

@@ -12,12 +12,14 @@
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
 
 import java.io.IOException;
+import java.util.Collections;
+import java.util.Map;
 import java.util.Objects;
 
 public class WarningInferenceResults implements InferenceResults {
 
     public static final String NAME = "warning";
-    public static final ParseField WARNING = new ParseField("warning");
+    public static final ParseField WARNING = new ParseField(NAME);
 
     private final String warning;
 
@@ -55,7 +57,12 @@ public int hashCode() {
     public void writeResult(IngestDocument document, String parentResultField) {
         ExceptionsHelper.requireNonNull(document, "document");
         ExceptionsHelper.requireNonNull(parentResultField, "resultField");
-        document.setFieldValue(parentResultField + "." + "warning", warning);
+        document.setFieldValue(parentResultField + "." + NAME, warning);
+    }
+
+    @Override
+    public Map<String, Object> writeResultToMap(String parentResultField) {
+        return Collections.singletonMap(parentResultField, Collections.singletonMap(NAME, warning));
     }
 
     @Override

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/ClassificationConfig.java

@@ -108,6 +108,7 @@ public String getTopClassesResultsField() {
         return topClassesResultsField;
     }
 
+    @Override
     public String getResultsField() {
         return resultsField;
     }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/InferenceConfig.java

@@ -22,4 +22,6 @@ public interface InferenceConfig extends NamedXContentObject, NamedWriteable {
     default boolean requestingImportance() {
         return false;
     }
+
+    String getResultsField();
 }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/NullInferenceConfig.java

@@ -23,6 +23,11 @@ public NullInferenceConfig(boolean requestingFeatureImportance) {
         this.requestingFeatureImportance = requestingFeatureImportance;
     }
 
+    @Override
+    public String getResultsField() {
+        return null;
+    }
+
     @Override
     public boolean isTargetTypeSupported(TargetType targetType) {
         return true;

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/RegressionConfig.java

@@ -82,6 +82,7 @@ public int getNumTopFeatureImportanceValues() {
         return numTopFeatureImportanceValues;
     }
 
+    @Override
     public String getResultsField() {
         return resultsField;
     }

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/inference/results/ClassificationInferenceResultsTests.java

@@ -10,6 +10,7 @@
 import org.elasticsearch.test.AbstractWireSerializingTestCase;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.ClassificationConfig;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.ClassificationConfigTests;
+import org.elasticsearch.xpack.core.ml.utils.MapHelper;
 
 import java.util.Arrays;
 import java.util.Collections;
@@ -81,6 +82,30 @@ public void testWriteResultsWithTopClasses() {
         assertThat(document.getFieldValue("result_field.my_results", String.class), equalTo("foo"));
     }
 
+    @SuppressWarnings("unchecked")
+    public void testWriteResultsToMapWithTopClasses() {
+        List<ClassificationInferenceResults.TopClassEntry> entries = Arrays.asList(
+                new ClassificationInferenceResults.TopClassEntry("foo", 0.7),
+                new ClassificationInferenceResults.TopClassEntry("bar", 0.2),
+                new ClassificationInferenceResults.TopClassEntry("baz", 0.1));
+        ClassificationInferenceResults result = new ClassificationInferenceResults(1.0,
+                "foo",
+                entries,
+                new ClassificationConfig(3, "my_results", "bar"));
+        Map<String, Object> resultsDoc = result.writeResultToMap("result_field");
+
+        List<?> list = (List<?>) MapHelper.dig("result_field.bar", resultsDoc);
+        assertThat(list.size(), equalTo(3));
+
+        for(int i = 0; i < 3; i++) {
+            Map<String, Object> map = (Map<String, Object>)list.get(i);
+            assertThat(map, equalTo(entries.get(i).asValueMap()));
+        }
+
+        Object value = MapHelper.dig("result_field.my_results", resultsDoc);
+        assertThat(value, equalTo("foo"));
+    }
+
     @Override
     protected ClassificationInferenceResults createTestInstance() {
         return createRandomResults();

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/inference/results/RegressionInferenceResultsTests.java

@@ -8,11 +8,12 @@
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.ingest.IngestDocument;
 import org.elasticsearch.test.AbstractWireSerializingTestCase;
-import org.elasticsearch.xpack.core.ml.inference.results.RegressionInferenceResults;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.RegressionConfig;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.RegressionConfigTests;
+import org.elasticsearch.xpack.core.ml.utils.MapHelper;
 
 import java.util.HashMap;
+import java.util.Map;
 
 import static org.hamcrest.Matchers.equalTo;
 
@@ -31,6 +32,14 @@ public void testWriteResults() {
         assertThat(document.getFieldValue("result_field.predicted_value", Double.class), equalTo(0.3));
     }
 
+    public void testWriteResultsToMap() {
+        RegressionInferenceResults result = new RegressionInferenceResults(0.3, RegressionConfig.EMPTY_PARAMS);
+        Map<String, Object> doc = result.writeResultToMap("result_field");
+
+        Object value = MapHelper.dig("result_field.predicted_value", doc);
+        assertThat(value, equalTo(0.3));
+    }
+
     @Override
     protected RegressionInferenceResults createTestInstance() {
         return createRandomResults();

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/inference/results/WarningInferenceResultsTests.java

@@ -8,8 +8,10 @@
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.ingest.IngestDocument;
 import org.elasticsearch.test.AbstractWireSerializingTestCase;
+import org.elasticsearch.xpack.core.ml.utils.MapHelper;
 
 import java.util.HashMap;
+import java.util.Map;
 
 import static org.hamcrest.Matchers.equalTo;
 
@@ -27,6 +29,14 @@ public void testWriteResults() {
         assertThat(document.getFieldValue("result_field.warning", String.class), equalTo("foo"));
     }
 
+    public void testWriteResultToMap() {
+        WarningInferenceResults result = new WarningInferenceResults("foo");
+        Map<String, Object> doc = result.writeResultToMap("result_field");
+
+        Object field = MapHelper.dig("result_field.warning", doc);
+        assertThat(field, equalTo("foo"));
+    }
+
     @Override
     protected WarningInferenceResults createTestInstance() {
         return createRandomResults();

x-pack/plugin/ml/qa/ml-with-security/build.gradle

@@ -123,6 +123,8 @@ integTest.runner {
     'ml/delete_model_snapshot/Test delete snapshot missing snapshotId',
     'ml/delete_model_snapshot/Test delete snapshot missing job_id',
     'ml/delete_model_snapshot/Test delete with in-use model',
+    'ml/fetch_inference/Test fetch regression',
+    'ml/fetch_inference/Test fetch classification',
     'ml/filter_crud/Test create filter api with mismatching body ID',
     'ml/filter_crud/Test create filter given invalid filter_id',
     'ml/filter_crud/Test get filter API with bad ID',

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java

@@ -47,10 +47,12 @@
 import org.elasticsearch.plugins.IngestPlugin;
 import org.elasticsearch.plugins.PersistentTaskPlugin;
 import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.plugins.SearchPlugin;
 import org.elasticsearch.plugins.SystemIndexPlugin;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestHandler;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.search.fetch.FetchSubPhase;
 import org.elasticsearch.threadpool.ExecutorBuilder;
 import org.elasticsearch.threadpool.ScalingExecutorBuilder;
 import org.elasticsearch.threadpool.ThreadPool;
@@ -211,6 +213,8 @@
 import org.elasticsearch.xpack.ml.inference.ingest.InferenceProcessor;
 import org.elasticsearch.xpack.ml.inference.loadingservice.ModelLoadingService;
 import org.elasticsearch.xpack.ml.inference.persistence.TrainedModelProvider;
+import org.elasticsearch.xpack.ml.inference.search.InferencePhase;
+import org.elasticsearch.xpack.ml.inference.search.InferenceSearchExtBuilder;
 import org.elasticsearch.xpack.ml.job.JobManager;
 import org.elasticsearch.xpack.ml.job.JobManagerHolder;
 import org.elasticsearch.xpack.ml.job.UpdateJobProcessNotifier;
@@ -318,7 +322,7 @@
 
 import static java.util.Collections.emptyList;
 
-public class MachineLearning extends Plugin implements SystemIndexPlugin, AnalysisPlugin, IngestPlugin, PersistentTaskPlugin {
+public class MachineLearning extends Plugin implements SystemIndexPlugin, AnalysisPlugin, IngestPlugin, PersistentTaskPlugin, SearchPlugin {
     public static final String NAME = "ml";
     public static final String BASE_PATH = "/_ml/";
     public static final String PRE_V7_BASE_PATH = "/_xpack/ml/";
@@ -414,6 +418,7 @@ public Set<DiscoveryNodeRole> getRoles() {
     private final SetOnce<DataFrameAnalyticsManager> dataFrameAnalyticsManager = new SetOnce<>();
     private final SetOnce<DataFrameAnalyticsAuditor> dataFrameAnalyticsAuditor = new SetOnce<>();
     private final SetOnce<MlMemoryTracker> memoryTracker = new SetOnce<>();
+    private final SetOnce<ModelLoadingService> modelLoadingService = new SetOnce<>();
 
     public MachineLearning(Settings settings, Path configPath) {
         this.settings = settings;
@@ -628,6 +633,7 @@ public Collection<Object> createComponents(Client client, ClusterService cluster
             clusterService,
             xContentRegistry,
             settings);
+        this.modelLoadingService.set(modelLoadingService);
 
         // Data frame analytics components
         AnalyticsProcessManager analyticsProcessManager = new AnalyticsProcessManager(client, threadPool, analyticsProcessFactory,
@@ -886,6 +892,18 @@ public Map<String, AnalysisProvider<TokenizerFactory>> getTokenizers() {
         return Collections.singletonMap(MlClassicTokenizer.NAME, MlClassicTokenizerFactory::new);
     }
 
+    @Override
+    public List<FetchSubPhase> getFetchSubPhases(FetchPhaseConstructionContext context) {
+        return Collections.singletonList(new InferencePhase(modelLoadingService));
+    }
+
+    @Override
+    public List<SearchExtSpec<?>> getSearchExts() {
+        return Collections.singletonList(
+                new SearchExtSpec<>(InferenceSearchExtBuilder.NAME, InferenceSearchExtBuilder::new,
+                        InferenceSearchExtBuilder::fromXContent));
+    }
+
     @Override
     public UnaryOperator<Map<String, IndexTemplateMetaData>> getIndexTemplateMetaDataUpgrader() {
         return UnaryOperator.identity();

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/loadingservice/LocalModel.java

@@ -8,13 +8,13 @@
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.xpack.core.ml.inference.TrainedModelDefinition;
 import org.elasticsearch.xpack.core.ml.inference.TrainedModelInput;
+import org.elasticsearch.xpack.core.ml.inference.results.ClassificationInferenceResults;
+import org.elasticsearch.xpack.core.ml.inference.results.InferenceResults;
+import org.elasticsearch.xpack.core.ml.inference.results.RegressionInferenceResults;
 import org.elasticsearch.xpack.core.ml.inference.results.WarningInferenceResults;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.InferenceConfig;
 import org.elasticsearch.xpack.core.ml.job.messages.Messages;
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
-import org.elasticsearch.xpack.core.ml.inference.results.ClassificationInferenceResults;
-import org.elasticsearch.xpack.core.ml.inference.results.InferenceResults;
-import org.elasticsearch.xpack.core.ml.inference.results.RegressionInferenceResults;
 import org.elasticsearch.xpack.core.ml.utils.MapHelper;
 
 import java.util.HashSet;
@@ -44,6 +44,11 @@ public String getModelId() {
         return modelId;
     }
 
+    @Override
+    public Set<String> getFieldNames() {
+        return fieldNames;
+    }
+
     @Override
     public String getResultsType() {
         switch (trainedModelDefinition.getTrainedModel().targetType()) {
@@ -53,23 +58,26 @@ public String getResultsType() {
                 return RegressionInferenceResults.NAME;
             default:
                 throw ExceptionsHelper.badRequestException("Model [{}] has unsupported target type [{}]",
-                    modelId,
-                    trainedModelDefinition.getTrainedModel().targetType());
+                        modelId,
+                        trainedModelDefinition.getTrainedModel().targetType());
         }
     }
 
     @Override
-    public void infer(Map<String, Object> fields, InferenceConfig config, ActionListener<InferenceResults> listener) {
+    public void infer(Map<String, Object> fields, InferenceConfig inferenceConfig, ActionListener<InferenceResults> listener) {
         try {
-            if (fieldNames.stream().allMatch(f -> MapHelper.dig(f, fields) == null)) {
-                listener.onResponse(new WarningInferenceResults(Messages.getMessage(INFERENCE_WARNING_ALL_FIELDS_MISSING, modelId)));
-                return;
-            }
-
-            listener.onResponse(trainedModelDefinition.infer(fields, config));
+            listener.onResponse(infer(fields, inferenceConfig));
         } catch (Exception e) {
             listener.onFailure(e);
         }
     }
 
+    @Override
+    public InferenceResults infer(Map<String, Object> fields, InferenceConfig config) {
+        if (fieldNames.stream().allMatch(f -> MapHelper.dig(f, fields) == null)) {
+            return new WarningInferenceResults(Messages.getMessage(INFERENCE_WARNING_ALL_FIELDS_MISSING, modelId));
+        }
+
+        return trainedModelDefinition.infer(fields, config);
+    }
 }

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/inference/loadingservice/Model.java

@@ -10,12 +10,17 @@
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.InferenceConfig;
 
 import java.util.Map;
+import java.util.Set;
 
 public interface Model {
 
     String getResultsType();
 
     void infer(Map<String, Object> fields, InferenceConfig inferenceConfig, ActionListener<InferenceResults> listener);
 
+    InferenceResults infer(Map<String, Object> fields, InferenceConfig inferenceConfig);
+
     String getModelId();
+
+    Set<String> getFieldNames();
 }