Add Get Aliases API to the high-level REST client

client/rest-high-level/src/main/java/org/elasticsearch/client/IndicesClient.java

@@ -24,6 +24,7 @@
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesResponse;
 import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
+import org.elasticsearch.action.admin.indices.alias.get.GetAliasesResponse;
 import org.elasticsearch.action.admin.indices.cache.clear.ClearIndicesCacheRequest;
 import org.elasticsearch.action.admin.indices.cache.clear.ClearIndicesCacheResponse;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
@@ -51,13 +52,15 @@
 import org.elasticsearch.action.admin.indices.settings.put.UpdateSettingsResponse;
 import org.elasticsearch.action.admin.indices.shrink.ResizeRequest;
 import org.elasticsearch.action.admin.indices.shrink.ResizeResponse;
+import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.action.admin.indices.template.put.PutIndexTemplateRequest;
 import org.elasticsearch.action.admin.indices.template.put.PutIndexTemplateResponse;
 
 import java.io.IOException;
 import java.util.Collections;
 
 import static java.util.Collections.emptySet;
+import static java.util.Collections.singleton;
 
 /**
  * A wrapper for the {@link RestHighLevelClient} that provides methods for accessing the Indices API.
@@ -435,6 +438,28 @@ public void rolloverAsync(RolloverRequest rolloverRequest, ActionListener<Rollov
                 listener, emptySet(), headers);
     }
 
+    /**
+     * Gets one or more aliases using the Get Index Aliases API
+     * <p>
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-aliases.html"> Indices Aliases API on
+     * elastic.co</a>
+     */
+    public GetAliasesResponse getAlias(GetAliasesRequest getAliasesRequest, Header... headers) throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(getAliasesRequest, RequestConverters::getAlias,
+                GetAliasesResponse::fromXContent, singleton(RestStatus.NOT_FOUND.getStatus()), headers);
+    }
+
+    /**
+     * Asynchronously gets one or more aliases using the Get Index Aliases API
+     * <p>
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-aliases.html"> Indices Aliases API on
+     * elastic.co</a>
+     */
+    public void getAliasAsync(GetAliasesRequest getAliasesRequest, ActionListener<GetAliasesResponse> listener, Header... headers) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(getAliasesRequest, RequestConverters::getAlias,
+                GetAliasesResponse::fromXContent, listener, singleton(RestStatus.NOT_FOUND.getStatus()), headers);
+    }
+
     /**
      * Updates specific index level settings using the Update Indices Settings API
      * <p>

client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java

@@ -44,8 +44,8 @@
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
 import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
 import org.elasticsearch.action.admin.indices.rollover.RolloverRequest;
-import org.elasticsearch.action.admin.indices.settings.put.UpdateSettingsRequest;
 import org.elasticsearch.action.admin.indices.settings.get.GetSettingsRequest;
+import org.elasticsearch.action.admin.indices.settings.put.UpdateSettingsRequest;
 import org.elasticsearch.action.admin.indices.shrink.ResizeRequest;
 import org.elasticsearch.action.admin.indices.shrink.ResizeType;
 import org.elasticsearch.action.admin.indices.template.put.PutIndexTemplateRequest;
@@ -671,6 +671,17 @@ static Request putTemplate(PutIndexTemplateRequest putIndexTemplateRequest) thro
         return request;
     }
 
+    static Request getAlias(GetAliasesRequest getAliasesRequest) {
+        String[] indices = getAliasesRequest.indices() == null ? Strings.EMPTY_ARRAY : getAliasesRequest.indices();
+        String[] aliases = getAliasesRequest.aliases() == null ? Strings.EMPTY_ARRAY : getAliasesRequest.aliases();
+        String endpoint = endpoint(indices, "_alias", aliases);
+        Request request = new Request(HttpGet.METHOD_NAME, endpoint);
+        Params params = new Params(request);
+        params.withIndicesOptions(getAliasesRequest.indicesOptions());
+        params.withLocal(getAliasesRequest.local());
+        return request;
+    }
+
     private static HttpEntity createEntity(ToXContent toXContent, XContentType xContentType) throws IOException {
         BytesRef source = XContentHelper.toXContent(toXContent, xContentType, false).toBytesRef();
         return new ByteArrayEntity(source.bytes, source.offset, source.length, createContentType(xContentType));

client/rest-high-level/src/main/java/org/elasticsearch/client/RestHighLevelClient.java

@@ -573,10 +573,10 @@ protected final <Req extends ActionRequest, Resp> Resp performRequest(Req reques
                 try {
                     return responseConverter.apply(e.getResponse());
                 } catch (Exception innerException) {
-                    //the exception is ignored as we now try to parse the response as an error.
-                    //this covers cases like get where 404 can either be a valid document not found response,
-                    //or an error for which parsing is completely different. We try to consider the 404 response as a valid one
-                    //first. If parsing of the response breaks, we fall back to parsing it as an error.
+                    // the exception is ignored as we now try to parse the response as an error.
+                    // this covers cases like get where 404 can either be a valid document not found response,
+                    // or an error for which parsing is completely different. We try to consider the 404 response as a valid one
+                    // first. If parsing of the response breaks, we fall back to parsing it as an error.
                     throw parseResponseException(e);
                 }
             }
@@ -642,10 +642,10 @@ public void onFailure(Exception exception) {
                         try {
                             actionListener.onResponse(responseConverter.apply(response));
                         } catch (Exception innerException) {
-                            //the exception is ignored as we now try to parse the response as an error.
-                            //this covers cases like get where 404 can either be a valid document not found response,
-                            //or an error for which parsing is completely different. We try to consider the 404 response as a valid one
-                            //first. If parsing of the response breaks, we fall back to parsing it as an error.
+                            // the exception is ignored as we now try to parse the response as an error.
+                            // this covers cases like get where 404 can either be a valid document not found response,
+                            // or an error for which parsing is completely different. We try to consider the 404 response as a valid one
+                            // first. If parsing of the response breaks, we fall back to parsing it as an error.
                             actionListener.onFailure(parseResponseException(responseException));
                         }
                     } else {