[ML] Do not create the .inference index as a side effect of calling usage (elastic#115023)

The Inference usage API calls GET _inference/_all and because the default
configs are persisted on read it causes the creation of the .inference index.
This action is undesirable and causes test failures by leaking the system index
out of the test clean up code.
# Conflicts:
#	muted-tests.yml
#	x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportGetInferenceModelAction.java

Author: davidkyle

x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/CreateFromDeploymentIT.java

@@ -109,6 +109,55 @@ public void testModelIdDoesNotMatch() throws IOException {
         );
     }
 
+    public void testNumAllocationsIsUpdated() throws IOException {
+        var modelId = "update_num_allocations";
+        var deploymentId = modelId;
+
+        CustomElandModelIT.createMlNodeTextExpansionModel(modelId, client());
+        var response = startMlNodeDeploymemnt(modelId, deploymentId);
+        assertOkOrCreated(response);
+
+        var inferenceId = "test_num_allocations_updated";
+        var putModel = putModel(inferenceId, endpointConfig(deploymentId), TaskType.SPARSE_EMBEDDING);
+        var serviceSettings = putModel.get("service_settings");
+        assertThat(
+            putModel.toString(),
+            serviceSettings,
+            is(
+                Map.of(
+                    "num_allocations",
+                    1,
+                    "num_threads",
+                    1,
+                    "model_id",
+                    "update_num_allocations",
+                    "deployment_id",
+                    "update_num_allocations"
+                )
+            )
+        );
+
+        assertOkOrCreated(updateMlNodeDeploymemnt(deploymentId, 2));
+
+        var updatedServiceSettings = getModel(inferenceId).get("service_settings");
+        assertThat(
+            updatedServiceSettings.toString(),
+            updatedServiceSettings,
+            is(
+                Map.of(
+                    "num_allocations",
+                    2,
+                    "num_threads",
+                    1,
+                    "model_id",
+                    "update_num_allocations",
+                    "deployment_id",
+                    "update_num_allocations"
+                )
+            )
+        );
+    }
+
     private String endpointConfig(String deploymentId) {
         return Strings.format("""
             {
@@ -147,6 +196,20 @@ private Response startMlNodeDeploymemnt(String modelId, String deploymentId) thr
         return client().performRequest(request);
     }
 
+    private Response updateMlNodeDeploymemnt(String deploymentId, int numAllocations) throws IOException {
+        String endPoint = "/_ml/trained_models/" + deploymentId + "/deployment/_update";
+
+        var body = Strings.format("""
+            {
+              "number_of_allocations": %d
+            }
+            """, numAllocations);
+
+        Request request = new Request("POST", endPoint);
+        request.setJsonEntity(body);
+        return client().performRequest(request);
+    }
+
     protected void stopMlNodeDeployment(String deploymentId) throws IOException {
         String endpoint = "/_ml/trained_models/" + deploymentId + "/deployment/_stop";
         Request request = new Request("POST", endpoint);

x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/InferenceCrudIT.java

@@ -24,6 +24,7 @@
 import java.util.stream.Stream;
 
 import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.equalToIgnoringCase;
 import static org.hamcrest.Matchers.hasSize;
@@ -326,4 +327,9 @@ public void testSupportedStream() throws Exception {
             deleteModel(modelId);
         }
     }
+
+    public void testGetZeroModels() throws IOException {
+        var models = getModels("_all", TaskType.RERANK);
+        assertThat(models, empty());
+    }
 }

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/action/TransportGetInferenceModelAction.java

@@ -126,6 +126,11 @@ private void getModelsByTaskType(TaskType taskType, ActionListener<GetInferenceM
     }
 
     private void parseModels(List<UnparsedModel> unparsedModels, ActionListener<GetInferenceModelAction.Response> listener) {
+        if (unparsedModels.isEmpty()) {
+            listener.onResponse(new GetInferenceModelAction.Response(List.of()));
+            return;
+        }
+
         var parsedModelsByService = new HashMap<String, List<Model>>();
         try {
             for (var unparsedModel : unparsedModels) {

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elasticsearch/ElasticsearchInternalModel.java

@@ -91,13 +91,8 @@ public ElasticsearchInternalServiceSettings getServiceSettings() {
         return (ElasticsearchInternalServiceSettings) super.getServiceSettings();
     }
 
-    public void updateNumAllocation(Integer numAllocations) {
-        this.internalServiceSettings = new ElasticsearchInternalServiceSettings(
-            numAllocations,
-            this.internalServiceSettings.getNumThreads(),
-            this.internalServiceSettings.modelId(),
-            this.internalServiceSettings.getAdaptiveAllocationsSettings()
-        );
+    public void updateNumAllocations(Integer numAllocations) {
+        this.internalServiceSettings.setNumAllocations(numAllocations);
     }
 
     @Override

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elasticsearch/ElasticsearchInternalService.java

@@ -778,10 +778,17 @@ public List<DefaultConfigId> defaultConfigIds() {
 
     @Override
     public void updateModelsWithDynamicFields(List<Model> models, ActionListener<List<Model>> listener) {
+        if (models.isEmpty()) {
+            listener.onResponse(models);
+            return;
+        }
+
         var modelsByDeploymentIds = new HashMap<String, ElasticsearchInternalModel>();
         for (var model : models) {
+            assert model instanceof ElasticsearchInternalModel;
+
             if (model instanceof ElasticsearchInternalModel esModel) {
-                modelsByDeploymentIds.put(esModel.internalServiceSettings.deloymentId(), esModel);
+                modelsByDeploymentIds.put(esModel.mlNodeDeploymentId(), esModel);
             } else {
                 listener.onFailure(
                     new ElasticsearchStatusException(
@@ -794,19 +801,14 @@ public void updateModelsWithDynamicFields(List<Model> models, ActionListener<Lis
             }
         }
 
-        if (modelsByDeploymentIds.isEmpty()) {
-            listener.onResponse(models);
-            return;
-        }
-
         String deploymentIds = String.join(",", modelsByDeploymentIds.keySet());
         client.execute(
             GetDeploymentStatsAction.INSTANCE,
             new GetDeploymentStatsAction.Request(deploymentIds),
             ActionListener.wrap(stats -> {
                 for (var deploymentStats : stats.getStats().results()) {
                     var model = modelsByDeploymentIds.get(deploymentStats.getDeploymentId());
-                    model.updateNumAllocation(deploymentStats.getNumberOfAllocations());
+                    model.updateNumAllocations(deploymentStats.getNumberOfAllocations());
                 }
                 listener.onResponse(new ArrayList<>(modelsByDeploymentIds.values()));
             }, e -> {

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/elasticsearch/ElasticsearchInternalServiceSettings.java

@@ -39,7 +39,7 @@ public class ElasticsearchInternalServiceSettings implements ServiceSettings {
     public static final String DEPLOYMENT_ID = "deployment_id";
     public static final String ADAPTIVE_ALLOCATIONS = "adaptive_allocations";
 
-    private final Integer numAllocations;
+    private Integer numAllocations;
     private final int numThreads;
     private final String modelId;
     private final AdaptiveAllocationsSettings adaptiveAllocationsSettings;
@@ -172,6 +172,10 @@ public ElasticsearchInternalServiceSettings(StreamInput in) throws IOException {
             : null;
     }
 
+    public void setNumAllocations(Integer numAllocations) {
+        this.numAllocations = numAllocations;
+    }
+
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         if (out.getTransportVersion().onOrAfter(TransportVersions.INFERENCE_ADAPTIVE_ALLOCATIONS)) {

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/services/elasticsearch/ElserInternalModelTests.java

@@ -21,10 +21,10 @@ public void testUpdateNumAllocation() {
             null
         );
 
-        model.updateNumAllocation(1);
-        assertEquals(1, model.internalServiceSettings.getNumAllocations().intValue());
+        model.updateNumAllocations(1);
+        assertEquals(1, model.getServiceSettings().getNumAllocations().intValue());
 
-        model.updateNumAllocation(null);
-        assertNull(model.internalServiceSettings.getNumAllocations());
+        model.updateNumAllocations(null);
+        assertNull(model.getServiceSettings().getNumAllocations());
     }
 }