REST high-level client: add support for exists alias (#28332)

Relates to #27205

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

@@ -21,6 +21,7 @@ package org.elasticsearch.client;
 
 import org.apache.http.Header;
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexResponse;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
@@ -35,7 +36,8 @@ import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexResponse;
 
 import java.io.IOException;
-import java.util.Collections;
+
+import static java.util.Collections.emptySet;
 
 /**
  * A wrapper for the {@link RestHighLevelClient} that provides methods for accessing the Indices API.
@@ -57,7 +59,7 @@ public final class IndicesClient {
      */
     public DeleteIndexResponse delete(DeleteIndexRequest deleteIndexRequest, Header... headers) throws IOException {
         return restHighLevelClient.performRequestAndParseEntity(deleteIndexRequest, Request::deleteIndex, DeleteIndexResponse::fromXContent,
-                Collections.emptySet(), headers);
+                emptySet(), headers);
     }
 
     /**
@@ -68,7 +70,7 @@ public final class IndicesClient {
      */
     public void deleteAsync(DeleteIndexRequest deleteIndexRequest, ActionListener<DeleteIndexResponse> listener, Header... headers) {
         restHighLevelClient.performRequestAsyncAndParseEntity(deleteIndexRequest, Request::deleteIndex, DeleteIndexResponse::fromXContent,
-                listener, Collections.emptySet(), headers);
+                listener, emptySet(), headers);
     }
 
     /**
@@ -79,7 +81,7 @@ public final class IndicesClient {
      */
     public CreateIndexResponse create(CreateIndexRequest createIndexRequest, Header... headers) throws IOException {
         return restHighLevelClient.performRequestAndParseEntity(createIndexRequest, Request::createIndex, CreateIndexResponse::fromXContent,
-                Collections.emptySet(), headers);
+                emptySet(), headers);
     }
 
     /**
@@ -90,7 +92,7 @@ public final class IndicesClient {
      */
     public void createAsync(CreateIndexRequest createIndexRequest, ActionListener<CreateIndexResponse> listener, Header... headers) {
         restHighLevelClient.performRequestAsyncAndParseEntity(createIndexRequest, Request::createIndex, CreateIndexResponse::fromXContent,
-                listener, Collections.emptySet(), headers);
+                listener, emptySet(), headers);
     }
 
     /**
@@ -101,7 +103,7 @@ public final class IndicesClient {
      */
     public PutMappingResponse putMapping(PutMappingRequest putMappingRequest, Header... headers) throws IOException {
         return restHighLevelClient.performRequestAndParseEntity(putMappingRequest, Request::putMapping, PutMappingResponse::fromXContent,
-                Collections.emptySet(), headers);
+                emptySet(), headers);
     }
 
     /**
@@ -113,7 +115,7 @@ public final class IndicesClient {
     public void putMappingAsync(PutMappingRequest putMappingRequest, ActionListener<PutMappingResponse> listener,
                                        Header... headers) {
         restHighLevelClient.performRequestAsyncAndParseEntity(putMappingRequest, Request::putMapping, PutMappingResponse::fromXContent,
-                listener, Collections.emptySet(), headers);
+                listener, emptySet(), headers);
     }
 
     /**
@@ -125,7 +127,7 @@ public final class IndicesClient {
      */
     public IndicesAliasesResponse updateAliases(IndicesAliasesRequest indicesAliasesRequest, Header... headers) throws IOException {
         return restHighLevelClient.performRequestAndParseEntity(indicesAliasesRequest, Request::updateAliases,
-                IndicesAliasesResponse::fromXContent, Collections.emptySet(), headers);
+                IndicesAliasesResponse::fromXContent, emptySet(), headers);
     }
 
     /**
@@ -138,7 +140,7 @@ public final class IndicesClient {
     public void updateAliasesAsync(IndicesAliasesRequest indicesAliasesRequestRequest, ActionListener<IndicesAliasesResponse> listener,
             Header... headers) {
         restHighLevelClient.performRequestAsyncAndParseEntity(indicesAliasesRequestRequest, Request::updateAliases,
-                IndicesAliasesResponse::fromXContent, listener, Collections.emptySet(), headers);
+                IndicesAliasesResponse::fromXContent, listener, emptySet(), headers);
     }
 
     /**
@@ -149,7 +151,7 @@ public final class IndicesClient {
      */
     public OpenIndexResponse open(OpenIndexRequest openIndexRequest, Header... headers) throws IOException {
         return restHighLevelClient.performRequestAndParseEntity(openIndexRequest, Request::openIndex, OpenIndexResponse::fromXContent,
-                Collections.emptySet(), headers);
+                emptySet(), headers);
     }
 
     /**
@@ -160,7 +162,7 @@ public final class IndicesClient {
      */
     public void openAsync(OpenIndexRequest openIndexRequest, ActionListener<OpenIndexResponse> listener, Header... headers) {
         restHighLevelClient.performRequestAsyncAndParseEntity(openIndexRequest, Request::openIndex, OpenIndexResponse::fromXContent,
-                listener, Collections.emptySet(), headers);
+                listener, emptySet(), headers);
     }
 
     /**
@@ -171,7 +173,7 @@ public final class IndicesClient {
      */
     public CloseIndexResponse close(CloseIndexRequest closeIndexRequest, Header... headers) throws IOException {
         return restHighLevelClient.performRequestAndParseEntity(closeIndexRequest, Request::closeIndex, CloseIndexResponse::fromXContent,
-                Collections.emptySet(), headers);
+                emptySet(), headers);
     }
 
     /**
@@ -182,6 +184,28 @@ public final class IndicesClient {
      */
     public void closeAsync(CloseIndexRequest closeIndexRequest, ActionListener<CloseIndexResponse> listener, Header... headers) {
         restHighLevelClient.performRequestAsyncAndParseEntity(closeIndexRequest, Request::closeIndex, CloseIndexResponse::fromXContent,
-                listener, Collections.emptySet(), headers);
+                listener, emptySet(), headers);
+    }
+
+    /**
+     * Checks if one or more aliases exist using the Aliases Exist 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 boolean existsAlias(GetAliasesRequest getAliasesRequest, Header... headers) throws IOException {
+        return restHighLevelClient.performRequest(getAliasesRequest, Request::existsAlias, RestHighLevelClient::convertExistsResponse,
+                emptySet(), headers);
+    }
+
+    /**
+     * Asynchronously checks if one or more aliases exist using the Aliases Exist 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 existsAliasAsync(GetAliasesRequest getAliasesRequest, ActionListener<Boolean> listener, Header... headers) {
+        restHighLevelClient.performRequestAsync(getAliasesRequest, Request::existsAlias, RestHighLevelClient::convertExistsResponse,
+                listener, emptySet(), headers);
     }
 }

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

@@ -29,6 +29,7 @@ import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.entity.ContentType;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.action.DocWriteRequest;
+import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
 import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
@@ -133,7 +134,7 @@ public final class Request {
     }
 
     static Request deleteIndex(DeleteIndexRequest deleteIndexRequest) {
-        String endpoint = endpoint(deleteIndexRequest.indices(), Strings.EMPTY_ARRAY, "");
+        String endpoint = endpoint(deleteIndexRequest.indices());
 
         Params parameters = Params.builder();
         parameters.withTimeout(deleteIndexRequest.timeout());
@@ -144,7 +145,7 @@ public final class Request {
     }
 
     static Request openIndex(OpenIndexRequest openIndexRequest) {
-        String endpoint = endpoint(openIndexRequest.indices(), Strings.EMPTY_ARRAY, "_open");
+        String endpoint = endpoint(openIndexRequest.indices(), "_open");
 
         Params parameters = Params.builder();
 
@@ -157,7 +158,7 @@ public final class Request {
     }
 
     static Request closeIndex(CloseIndexRequest closeIndexRequest) {
-        String endpoint = endpoint(closeIndexRequest.indices(), Strings.EMPTY_ARRAY, "_close");
+        String endpoint = endpoint(closeIndexRequest.indices(), "_close");
 
         Params parameters = Params.builder();
 
@@ -169,7 +170,7 @@ public final class Request {
     }
 
     static Request createIndex(CreateIndexRequest createIndexRequest) throws IOException {
-        String endpoint = endpoint(createIndexRequest.indices(), Strings.EMPTY_ARRAY, "");
+        String endpoint = endpoint(createIndexRequest.indices());
 
         Params parameters = Params.builder();
         parameters.withTimeout(createIndexRequest.timeout());
@@ -472,13 +473,44 @@ public final class Request {
         return new Request(HttpPost.METHOD_NAME, "/_msearch", params.getParams(), entity);
     }
 
+    static Request existsAlias(GetAliasesRequest getAliasesRequest) {
+        Params params = Params.builder();
+        params.withIndicesOptions(getAliasesRequest.indicesOptions());
+        params.withLocal(getAliasesRequest.local());
+        if (getAliasesRequest.indices().length == 0 && getAliasesRequest.aliases().length == 0) {
+            throw new IllegalArgumentException("existsAlias requires at least an alias or an index");
+        }
+        String endpoint = endpoint(getAliasesRequest.indices(), "_alias", getAliasesRequest.aliases());
+        return new Request("HEAD", endpoint, params.getParams(), null);
+    }
+
     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));
     }
 
+    static String endpoint(String index, String type, String id) {
+        return buildEndpoint(index, type, id);
+    }
+
+    static String endpoint(String index, String type, String id, String endpoint) {
+        return buildEndpoint(index, type, id, endpoint);
+    }
+
+    static String endpoint(String[] indices) {
+        return buildEndpoint(String.join(",", indices));
+    }
+
+    static String endpoint(String[] indices, String endpoint) {
+        return buildEndpoint(String.join(",", indices), endpoint);
+    }
+
     static String endpoint(String[] indices, String[] types, String endpoint) {
-        return endpoint(String.join(",", indices), String.join(",", types), endpoint);
+        return buildEndpoint(String.join(",", indices), String.join(",", types), endpoint);
+    }
+
+    static String endpoint(String[] indices, String endpoint, String[] suffixes) {
+        return buildEndpoint(String.join(",", indices), endpoint, String.join(",", suffixes));
     }
 
     static String endpoint(String[] indices, String endpoint, String type) {
@@ -486,9 +518,9 @@ public final class Request {
     }
 
     /**
-     * Utility method to build request's endpoint.
+     * Utility method to build request's endpoint given its parts as strings
      */
-    static String endpoint(String... parts) {
+    static String buildEndpoint(String... parts) {
         StringJoiner joiner = new StringJoiner("/", "/", "");
         for (String part : parts) {
             if (Strings.hasLength(part)) {
@@ -656,6 +688,11 @@ public final class Request {
             return this;
         }
 
+        Params withLocal(boolean local) {
+            putParam("local", Boolean.toString(local));
+            return this;
+        }
+
         Map<String, String> getParams() {
             return Collections.unmodifiableMap(params);
         }

client/rest-high-level/src/test/java/org/elasticsearch/client/IndicesClientIT.java

@@ -22,6 +22,7 @@ package org.elasticsearch.client;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.ElasticsearchStatusException;
 import org.elasticsearch.action.admin.indices.alias.Alias;
+import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexResponse;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
@@ -353,6 +354,22 @@ public class IndicesClientIT extends ESRestHighLevelClientTestCase {
         return RestStatus.OK.getStatus() == response.getStatusLine().getStatusCode();
     }
 
+    public void testExistsAlias() throws IOException {
+        GetAliasesRequest getAliasesRequest = new GetAliasesRequest("alias");
+        assertFalse(execute(getAliasesRequest, highLevelClient().indices()::existsAlias, highLevelClient().indices()::existsAliasAsync));
+
+        createIndex("index");
+        client().performRequest("PUT", "/index/_alias/alias");
+        assertTrue(execute(getAliasesRequest, highLevelClient().indices()::existsAlias, highLevelClient().indices()::existsAliasAsync));
+
+        GetAliasesRequest getAliasesRequest2 = new GetAliasesRequest();
+        getAliasesRequest2.aliases("alias");
+        getAliasesRequest2.indices("index");
+        assertTrue(execute(getAliasesRequest2, highLevelClient().indices()::existsAlias, highLevelClient().indices()::existsAliasAsync));
+        getAliasesRequest2.indices("does_not_exist");
+        assertFalse(execute(getAliasesRequest2, highLevelClient().indices()::existsAlias, highLevelClient().indices()::existsAliasAsync));
+    }
+
     @SuppressWarnings("unchecked")
     private Map<String, Object> getIndexMetadata(String index) throws IOException {
         Response response = client().performRequest("GET", index);

client/rest-high-level/src/test/java/org/elasticsearch/client/RequestTests.java

@@ -30,6 +30,7 @@ import org.apache.http.entity.ContentType;
 import org.apache.http.entity.StringEntity;
 import org.apache.http.util.EntityUtils;
 import org.elasticsearch.action.DocWriteRequest;
+import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest.AliasActions;
@@ -983,6 +984,44 @@ public class RequestTests extends ESTestCase {
         assertEquals(REQUEST_BODY_CONTENT_TYPE.mediaTypeWithoutParameters(), request.getEntity().getContentType().getValue());
     }
 
+    public void testExistsAlias() {
+        GetAliasesRequest getAliasesRequest = new GetAliasesRequest();
+        String[] indices = randomIndicesNames(0, 5);
+        getAliasesRequest.indices(indices);
+        //the HEAD endpoint requires at least an alias or an index
+        String[] aliases = randomIndicesNames(indices.length == 0 ? 1 : 0, 5);
+        getAliasesRequest.aliases(aliases);
+        Map<String, String> expectedParams = new HashMap<>();
+        if (randomBoolean()) {
+            boolean local = randomBoolean();
+            getAliasesRequest.local(local);
+        }
+        expectedParams.put("local", Boolean.toString(getAliasesRequest.local()));
+
+        setRandomIndicesOptions(getAliasesRequest::indicesOptions, getAliasesRequest::indicesOptions, expectedParams);
+
+        Request request = Request.existsAlias(getAliasesRequest);
+        StringJoiner expectedEndpoint = new StringJoiner("/", "/", "");
+        String index = String.join(",", indices);
+        if (Strings.hasLength(index)) {
+            expectedEndpoint.add(index);
+        }
+        expectedEndpoint.add("_alias");
+        String alias = String.join(",", aliases);
+        if (Strings.hasLength(alias)) {
+            expectedEndpoint.add(alias);
+        }
+        assertEquals(expectedEndpoint.toString(), request.getEndpoint());
+        assertEquals(expectedParams, request.getParameters());
+        assertNull(request.getEntity());
+    }
+
+    public void testExistsAliasNoAliasNoIndex() {
+        GetAliasesRequest getAliasesRequest = new GetAliasesRequest();
+        IllegalArgumentException iae = expectThrows(IllegalArgumentException.class, () -> Request.existsAlias(getAliasesRequest));
+        assertEquals("existsAlias requires at least an alias or an index", iae.getMessage());
+    }
+
     private static void assertToXContentBody(ToXContent expectedBody, HttpEntity actualEntity) throws IOException {
         BytesReference expectedBytes = XContentHelper.toXContent(expectedBody, REQUEST_BODY_CONTENT_TYPE, false);
         assertEquals(XContentType.JSON.mediaTypeWithoutParameters(), actualEntity.getContentType().getValue());
@@ -1017,14 +1056,25 @@ public class RequestTests extends ESTestCase {
         assertEquals("1", requestParams.values().iterator().next());
     }
 
+    public void testBuildEndpoint() {
+        assertEquals("/", Request.buildEndpoint());
+        assertEquals("/", Request.buildEndpoint(Strings.EMPTY_ARRAY));
+        assertEquals("/", Request.buildEndpoint(""));
+        assertEquals("/a/b", Request.buildEndpoint("a", "b"));
+        assertEquals("/a/b/_create", Request.buildEndpoint("a", "b", "_create"));
+        assertEquals("/a/b/c/_create", Request.buildEndpoint("a", "b", "c", "_create"));
+        assertEquals("/a/_create", Request.buildEndpoint("a", null, null, "_create"));
+    }
+
     public void testEndpoint() {
-        assertEquals("/", Request.endpoint());
-        assertEquals("/", Request.endpoint(Strings.EMPTY_ARRAY));
-        assertEquals("/", Request.endpoint(""));
-        assertEquals("/a/b", Request.endpoint("a", "b"));
-        assertEquals("/a/b/_create", Request.endpoint("a", "b", "_create"));
-        assertEquals("/a/b/c/_create", Request.endpoint("a", "b", "c", "_create"));
-        assertEquals("/a/_create", Request.endpoint("a", null, null, "_create"));
+        assertEquals("/index/type/id", Request.endpoint("index", "type", "id"));
+        assertEquals("/index/type/id/_endpoint", Request.endpoint("index", "type", "id", "_endpoint"));
+        assertEquals("/index1,index2", Request.endpoint(new String[]{"index1", "index2"}));
+        assertEquals("/index1,index2/_endpoint", Request.endpoint(new String[]{"index1", "index2"}, "_endpoint"));
+        assertEquals("/index1,index2/type1,type2/_endpoint", Request.endpoint(new String[]{"index1", "index2"},
+                new String[]{"type1", "type2"}, "_endpoint"));
+        assertEquals("/index1,index2/_endpoint/suffix1,suffix2", Request.endpoint(new String[]{"index1", "index2"},
+                "_endpoint", new String[]{"suffix1", "suffix2"}));
     }
 
     public void testCreateContentType() {

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/IndicesClientDocumentationIT.java

@@ -22,6 +22,7 @@ package org.elasticsearch.client.documentation;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.admin.indices.alias.Alias;
+import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexRequest;
 import org.elasticsearch.action.admin.indices.close.CloseIndexResponse;
 import org.elasticsearch.action.admin.indices.alias.IndicesAliasesRequest;
@@ -304,16 +305,10 @@ public class IndicesClientDocumentationIT extends ESRestHighLevelClientTestCase
                 }
             });
             // end::put-mapping-execute-async
-
-            assertBusy(() -> {
-                // TODO Use Indices Exist API instead once it exists
-                Response response = client.getLowLevelClient().performRequest("HEAD", "twitter");
-                assertTrue(RestStatus.OK.getStatus() == response.getStatusLine().getStatusCode());
-            });
         }
     }
 
-    public void testOpenIndex() throws IOException {
+    public void testOpenIndex() throws Exception {
         RestHighLevelClient client = highLevelClient();
 
         {
@@ -384,7 +379,7 @@ public class IndicesClientDocumentationIT extends ESRestHighLevelClientTestCase
         }
     }
 
-    public void testCloseIndex() throws IOException {
+    public void testCloseIndex() throws Exception {
         RestHighLevelClient client = highLevelClient();
 
         {
@@ -432,19 +427,59 @@ public class IndicesClientDocumentationIT extends ESRestHighLevelClientTestCase
                 }
             });
             // end::close-index-execute-async
+
         }
+    }
+
+    public void testExistsAlias() throws Exception {
+        RestHighLevelClient client = highLevelClient();
 
         {
-            // tag::close-index-notfound
-            try {
-                CloseIndexRequest request = new CloseIndexRequest("does_not_exist");
-                client.indices().close(request);
-            } catch (ElasticsearchException exception) {
-                if (exception.status() == RestStatus.BAD_REQUEST) {
+            CreateIndexResponse createIndexResponse = client.indices().create(new CreateIndexRequest("index")
+                    .alias(new Alias("alias")));
+            assertTrue(createIndexResponse.isAcknowledged());
+        }
+
+        {
+            // tag::exists-alias-request
+            GetAliasesRequest request = new GetAliasesRequest();
+            GetAliasesRequest requestWithAlias = new GetAliasesRequest("alias1");
+            GetAliasesRequest requestWithAliases = new GetAliasesRequest(new String[]{"alias1", "alias2"});
+            // end::exists-alias-request
+
+            // tag::exists-alias-request-alias
+            request.aliases("alias"); // <1>
+            // end::exists-alias-request-alias
+            // tag::exists-alias-request-indices
+            request.indices("index"); // <1>
+            // end::exists-alias-request-indices
+
+            // tag::exists-alias-request-indicesOptions
+            request.indicesOptions(IndicesOptions.lenientExpandOpen()); // <1>
+            // end::exists-alias-request-indicesOptions
+
+            // tag::exists-alias-request-local
+            request.local(true); // <1>
+            // end::exists-alias-request-local
+
+            // tag::exists-alias-execute
+            boolean exists = client.indices().existsAlias(request);
+            // end::exists-alias-execute
+            assertTrue(exists);
+
+            // tag::exists-alias-execute-async
+            client.indices().existsAliasAsync(request, new ActionListener<Boolean>() {
+                @Override
+                public void onResponse(Boolean exists) {
                     // <1>
                 }
-            }
-            // end::close-index-notfound
+
+                @Override
+                public void onFailure(Exception e) {
+                    // <2>
+                }
+            });
+            // end::exists-alias-execute-async
         }
     }
 

docs/java-rest/high-level/apis/exists_alias.asciidoc

@@ -0,0 +1,69 @@
+[[java-rest-high-exists-alias]]
+=== Exists Alias API
+
+[[java-rest-high-exists-alias-request]]
+==== Exists Alias Request
+
+The Exists Alias API uses `GetAliasesRequest` as its request object.
+One or more aliases can be optionally provided either at construction
+time or later on through the relevant setter method.
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-request]
+--------------------------------------------------
+
+==== Optional arguments
+The following arguments can optionally be provided:
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-request-alias]
+--------------------------------------------------
+<1> One or more aliases to look for
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-request-indices]
+--------------------------------------------------
+<1> The index or indices that the alias is associated with
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-request-indicesOptions]
+--------------------------------------------------
+<1> Setting `IndicesOptions` controls how unavailable indices are resolved and
+how wildcard expressions are expanded
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-request-local]
+--------------------------------------------------
+<1> The `local` flag (defaults to `false`) controls whether the aliases need
+to be looked up in the local cluster state or in the cluster state held by
+the elected master node.
+
+[[java-rest-high-exists-alias-sync]]
+==== Synchronous Execution
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-execute]
+--------------------------------------------------
+
+[[java-rest-high-exists-alias-async]]
+==== Asynchronous Execution
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests}/IndicesClientDocumentationIT.java[exists-alias-execute-async]
+--------------------------------------------------
+<1> Called when the execution is successfully completed. The response is
+provided as an argument
+<2> Called in case of failure. The raised exception is provided as an argument
+
+[[java-rest-high-exists-alias-response]]
+==== Exists Alias Response
+
+The Exists Alias API returns a `boolean` that indicates whether the provided
+alias (or aliases) was found or not.

docs/java-rest/high-level/apis/index.asciidoc

@@ -10,6 +10,8 @@ include::putmapping.asciidoc[]
 
 include::update_aliases.asciidoc[]
 
+include::exists_alias.asciidoc[]
+
 include::_index.asciidoc[]
 
 include::get.asciidoc[]

docs/java-rest/high-level/supported-apis.asciidoc

@@ -10,6 +10,7 @@ Indices APIs::
 * <<java-rest-high-close-index>>
 * <<java-rest-high-put-mapping>>
 * <<java-rest-high-update-aliases>>
+* <<java-rest-high-exists-alias>>
 
 Single document APIs::
 * <<java-rest-high-document-index>>