Initial impelmentation of CreateIndex

Signed-off-by: Owais Kazi <[email protected]>

src/main/java/org/opensearch/flowframework/workflow/CreateIndexStep.java

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+/*
+ * Copyright OpenSearch Contributors
+ * 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.flowframework.workflow;
+
+import com.google.common.base.Charsets;
+import com.google.common.io.Resources;
+import org.opensearch.action.admin.indices.create.CreateIndexRequest;
+import org.opensearch.client.AdminClient;
+import org.opensearch.common.xcontent.XContentType;
+
+import java.io.IOException;
+import java.net.URL;
+import java.util.concurrent.CompletableFuture;
+
+public class CreateIndexStep implements Workflow {
+
+    AdminClient adminClient;
+
+    @Override
+    public CompletableFuture<Workflow> execute() throws Exception {
+
+        // ActionListener<CreateIndexResponse> actionListener
+        CreateIndexRequest request = new CreateIndexRequest(indexName).mapping(getIndexMappings(fileName), XContentType.JSON)
+            .settings(settings);
+        adminClient.indices().create(request, actionListener);
+
+    }
+
+    /**
+     * Get index mapping json content.
+     *
+     * @return index mapping
+     * @throws IOException IOException if mapping file can't be read correctly
+     */
+    public static String getIndexMappings(String mappingFileName) throws IOException {
+        URL url = CreateIndexStep.class.getClassLoader().getResource(mappingFileName);
+        return Resources.toString(url, Charsets.UTF_8);
+    }
+}

src/main/resources/mappings/knn-index-mapping.json

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+