ReactiveElasticsearchOperations indexName is encoded twice.

src/main/java/org/springframework/data/elasticsearch/client/reactive/DefaultWebClientProvider.java

@@ -27,6 +27,7 @@
 import org.springframework.util.Assert;
 import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.reactive.function.client.WebClient.Builder;
+import org.springframework.web.util.DefaultUriBuilderFactory;
 
 /**
  * Default {@link WebClientProvider} that uses cached {@link WebClient} instances per {@code hostAndPort}.
@@ -155,8 +156,13 @@ protected WebClient createWebClientForSocketAddress(InetSocketAddress socketAddr
 
 		String baseUrl = String.format("%s://%s:%d%s", this.scheme, socketAddress.getHostString(), socketAddress.getPort(),
 				pathPrefix == null ? "" : '/' + pathPrefix);
+
+		DefaultUriBuilderFactory uriBuilderFactory = new DefaultUriBuilderFactory(baseUrl);
+		// the template will already be encoded by the RequestConverters methods
+		uriBuilderFactory.setEncodingMode(DefaultUriBuilderFactory.EncodingMode.VALUES_ONLY);
+		builder.uriBuilderFactory(uriBuilderFactory); //
+
 		WebClient webClient = builder //
-				.baseUrl(baseUrl) //
 				.filter((request, next) -> next.exchange(request) //
 						.doOnError(errorListener)) //
 				.build(); //

src/test/java/org/springframework/data/elasticsearch/core/ReactiveElasticsearchTemplateIntegrationTests.java

@@ -32,6 +32,8 @@
 import java.lang.Long;
 import java.lang.Object;
 import java.net.ConnectException;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -1031,6 +1033,32 @@ void shouldReturnMonoOfSearchPage() {
 					assertThat(searchHits.getSearchHits().size()).isEqualTo(5);
 				}).verifyComplete();
 	}
+
+	@Test // #1665
+	@DisplayName("should be able to process date-math-index names")
+	void shouldBeAbleToProcessDateMathIndexNames() {
+
+		String indexName = "foo-" + LocalDate.now().format(DateTimeFormatter.ofPattern("yyyy.MM"));
+		String dateMathIndexName = "<foo-{now/M{yyyy.MM}}>";
+
+		template.indexOps(IndexCoordinates.of(dateMathIndexName)) //
+				.create() //
+				.as(StepVerifier::create) //
+				.expectNext(true) //
+				.verifyComplete(); //
+
+		template.indexOps(IndexCoordinates.of(indexName)) //
+				.exists() //
+				.as(StepVerifier::create) //
+				.expectNext(true) //
+				.verifyComplete(); //
+
+		template.indexOps(IndexCoordinates.of(dateMathIndexName)) //
+				.delete() //
+				.as(StepVerifier::create) //
+				.expectNext(true) //
+				.verifyComplete(); //
+	}
 	// endregion
 
 	// region Helper functions
@@ -1128,5 +1156,6 @@ static class VersionedEntity {
 		@Id private String id;
 		@Version private Long version;
 	}
+
 	// endregion
 }