[ML] Filter empty task settings objects from the API response (#114389)

Inference endpoints that do not define task settings or where there are 
no defaults return an empty task_setting object. Filter this object from 
the response

Author: davidkyle

docs/changelog/114389.yaml

@@ -0,0 +1,5 @@
+pr: 114389
+summary: Filter empty task settings objects from the API response
+area: Machine Learning
+type: enhancement
+issues: []

server/src/main/java/org/elasticsearch/inference/EmptyTaskSettings.java

@@ -29,6 +29,11 @@ public EmptyTaskSettings(StreamInput in) {
         this();
     }
 
+    @Override
+    public boolean isEmpty() {
+        return true;
+    }
+
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject();

server/src/main/java/org/elasticsearch/inference/ModelConfigurations.java

@@ -173,7 +173,11 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         builder.field(TaskType.NAME, taskType.toString());
         builder.field(SERVICE, service);
         builder.field(SERVICE_SETTINGS, serviceSettings);
-        builder.field(TASK_SETTINGS, taskSettings);
+        // Always write task settings to the index even if empty.
+        // But do not show empty settings in the response
+        if (params.paramAsBoolean(USE_ID_FOR_INDEX, false) || (taskSettings != null && taskSettings.isEmpty() == false)) {
+            builder.field(TASK_SETTINGS, taskSettings);
+        }
         if (chunkingSettings != null) {
             builder.field(CHUNKING_SETTINGS, chunkingSettings);
         }
@@ -192,7 +196,11 @@ public XContentBuilder toFilteredXContent(XContentBuilder builder, Params params
         builder.field(TaskType.NAME, taskType.toString());
         builder.field(SERVICE, service);
         builder.field(SERVICE_SETTINGS, serviceSettings.getFilteredXContentObject());
-        builder.field(TASK_SETTINGS, taskSettings);
+        // Always write task settings to the index even if empty.
+        // But do not show empty settings in the response
+        if (params.paramAsBoolean(USE_ID_FOR_INDEX, false) || (taskSettings != null && taskSettings.isEmpty() == false)) {
+            builder.field(TASK_SETTINGS, taskSettings);
+        }
         if (chunkingSettings != null) {
             builder.field(CHUNKING_SETTINGS, chunkingSettings);
         }

server/src/main/java/org/elasticsearch/inference/TaskSettings.java

@@ -12,4 +12,6 @@
 import org.elasticsearch.common.io.stream.VersionedNamedWriteable;
 import org.elasticsearch.xcontent.ToXContentObject;
 
-public interface TaskSettings extends ToXContentObject, VersionedNamedWriteable {}
+public interface TaskSettings extends ToXContentObject, VersionedNamedWriteable {
+    boolean isEmpty();
+}

x-pack/plugin/inference/qa/mixed-cluster/src/javaRestTest/java/org/elasticsearch/xpack/inference/qa/mixed/OpenAIServiceMixedIT.java

@@ -19,11 +19,14 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.hamcrest.Matchers.anEmptyMap;
+import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.hasEntry;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.nullValue;
 
 public class OpenAIServiceMixedIT extends BaseMixedTestCase {
 
@@ -118,14 +121,13 @@ public void testOpenAiCompletions() throws IOException {
         put(inferenceId, chatCompletionsConfig(getUrl(openAiChatCompletionsServer)), TaskType.COMPLETION);
 
         var configsMap = get(TaskType.COMPLETION, inferenceId);
-        logger.warn("Configs: {}", configsMap);
         var configs = (List<Map<String, Object>>) configsMap.get("endpoints");
         assertThat(configs, hasSize(1));
         assertEquals("openai", configs.get(0).get("service"));
         var serviceSettings = (Map<String, Object>) configs.get(0).get("service_settings");
         assertThat(serviceSettings, hasEntry("model_id", "gpt-4"));
         var taskSettings = (Map<String, Object>) configs.get(0).get("task_settings");
-        assertThat(taskSettings.keySet(), empty());
+        assertThat(taskSettings, anyOf(nullValue(), anEmptyMap()));
 
         assertCompletionInference(inferenceId);
     }

x-pack/plugin/inference/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/xpack/application/CohereServiceUpgradeIT.java

@@ -22,10 +22,13 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.hamcrest.Matchers.anEmptyMap;
+import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.hasEntry;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.nullValue;
 import static org.hamcrest.Matchers.oneOf;
 
 public class CohereServiceUpgradeIT extends InferenceUpgradeTestCase {
@@ -122,7 +125,7 @@ public void testCohereEmbeddings() throws IOException {
             assertThat(serviceSettings, hasEntry("model_id", "embed-english-light-v3.0"));
             assertThat(serviceSettings, hasEntry("embedding_type", "byte"));
             var taskSettings = (Map<String, Object>) configs.get(0).get("task_settings");
-            assertThat(taskSettings.keySet(), empty());
+            assertThat(taskSettings, anyOf(nullValue(), anEmptyMap()));
 
             // Inference on old cluster models
             assertEmbeddingInference(oldClusterIdInt8, CohereEmbeddingType.BYTE);

x-pack/plugin/inference/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/xpack/application/HuggingFaceServiceUpgradeIT.java

@@ -20,9 +20,12 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.hamcrest.Matchers.anEmptyMap;
+import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.nullValue;
 
 public class HuggingFaceServiceUpgradeIT extends InferenceUpgradeTestCase {
 
@@ -132,7 +135,7 @@ public void testElser() throws IOException {
             var configs = (List<Map<String, Object>>) get(testTaskType, oldClusterId).get("endpoints");
             assertEquals("hugging_face", configs.get(0).get("service"));
             var taskSettings = (Map<String, Object>) configs.get(0).get("task_settings");
-            assertThat(taskSettings.keySet(), empty());
+            assertThat(taskSettings, anyOf(nullValue(), anEmptyMap()));
 
             assertElser(oldClusterId);
 

x-pack/plugin/inference/qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/xpack/application/OpenAiServiceUpgradeIT.java

@@ -19,10 +19,13 @@
 import java.util.List;
 import java.util.Map;
 
+import static org.hamcrest.Matchers.anEmptyMap;
+import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.hasEntry;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.not;
+import static org.hamcrest.Matchers.nullValue;
 
 public class OpenAiServiceUpgradeIT extends InferenceUpgradeTestCase {
 
@@ -91,7 +94,7 @@ public void testOpenAiEmbeddings() throws IOException {
             // model id is moved to service settings
             assertThat(serviceSettings, hasEntry("model_id", "text-embedding-ada-002"));
             var taskSettings = (Map<String, Object>) configs.get(0).get("task_settings");
-            assertThat(taskSettings.keySet(), empty());
+            assertThat(taskSettings, anyOf(nullValue(), anEmptyMap()));
 
             // Inference on old cluster model
             assertEmbeddingInference(oldClusterId);
@@ -145,7 +148,7 @@ public void testOpenAiCompletions() throws IOException {
             var serviceSettings = (Map<String, Object>) configs.get(0).get("service_settings");
             assertThat(serviceSettings, hasEntry("model_id", "gpt-4"));
             var taskSettings = (Map<String, Object>) configs.get(0).get("task_settings");
-            assertThat(taskSettings.keySet(), empty());
+            assertThat(taskSettings, anyOf(nullValue(), anEmptyMap()));
 
             assertCompletionInference(oldClusterId);
         } else if (isUpgradedCluster()) {
@@ -154,7 +157,7 @@ public void testOpenAiCompletions() throws IOException {
             var serviceSettings = (Map<String, Object>) configs.get(0).get("service_settings");
             assertThat(serviceSettings, hasEntry("model_id", "gpt-4"));
             var taskSettings = (Map<String, Object>) configs.get(0).get("task_settings");
-            assertThat(taskSettings.keySet(), empty());
+            assertThat(taskSettings, anyOf(nullValue(), anEmptyMap()));
 
             assertCompletionInference(oldClusterId);
 

x-pack/plugin/inference/qa/test-service-plugin/src/main/java/org/elasticsearch/xpack/inference/mock/AbstractTestInferenceService.java

@@ -23,6 +23,7 @@
 import org.elasticsearch.xcontent.XContentBuilder;
 
 import java.io.IOException;
+import java.util.HashMap;
 import java.util.Map;
 
 public abstract class AbstractTestInferenceService implements InferenceService {
@@ -47,7 +48,7 @@ protected static Map<String, Object> getTaskSettingsMap(Map<String, Object> sett
         if (settings.containsKey(ModelConfigurations.TASK_SETTINGS)) {
             taskSettingsMap = (Map<String, Object>) settings.remove(ModelConfigurations.TASK_SETTINGS);
         } else {
-            taskSettingsMap = Map.of();
+            taskSettingsMap = new HashMap<>();
         }
 
         return taskSettingsMap;
@@ -133,6 +134,11 @@ public TestTaskSettings(StreamInput in) throws IOException {
             this(in.readOptionalVInt());
         }
 
+        @Override
+        public boolean isEmpty() {
+            return temperature == null;
+        }
+
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             out.writeOptionalVInt(temperature);

x-pack/plugin/inference/src/internalClusterTest/java/org/elasticsearch/xpack/inference/integration/ModelRegistryIT.java

@@ -592,6 +592,11 @@ public TransportVersion getMinimalSupportedVersion() {
             public void writeTo(StreamOutput out) throws IOException {
 
             }
+
+            @Override
+            public boolean isEmpty() {
+                return true;
+            }
         }
 
         record TestSecretSettings(String key) implements SecretSettings {