Also rename write data stream alias during a restore. (#73588)

Rename during a restore should also rename write data stream in data stream alias.

Relates to #66163

Author: martijnvg

server/src/main/java/org/elasticsearch/snapshots/RestoreService.java

@@ -1198,7 +1198,11 @@ private void applyDataStreamRestores(ClusterState currentState, Metadata.Builder
                         List<String> renamedDataStreams = alias.getDataStreams().stream()
                             .map(s -> s.replaceAll(request.renamePattern(), request.renameReplacement()))
                             .collect(Collectors.toList());
-                        return new DataStreamAlias(alias.getName(), renamedDataStreams, alias.getWriteDataStream());
+                        String writeDataStream = alias.getWriteDataStream();
+                        if (writeDataStream != null) {
+                            writeDataStream = writeDataStream.replaceAll(request.renamePattern(), request.renameReplacement());
+                        }
+                        return new DataStreamAlias(alias.getName(), renamedDataStreams, writeDataStream);
                     } else {
                         return alias;
                     }

x-pack/plugin/data-streams/src/internalClusterTest/java/org/elasticsearch/datastreams/DataStreamsSnapshotsIT.java

@@ -78,6 +78,7 @@ public class DataStreamsSnapshotsIT extends AbstractSnapshotIntegTestCase {
     private String dsBackingIndexName;
     private String otherDsBackingIndexName;
     private String ds2BackingIndexName;
+    private String otherDs2BackingIndexName;
     private String id;
 
     @Override
@@ -109,6 +110,7 @@ public void setup() throws Exception {
         otherDsBackingIndexName = getDataStreamResponse.getDataStreams().get(1).getDataStream().getIndices().get(0).getName();
         // Will be used in some tests, to test renaming while restoring a snapshot:
         ds2BackingIndexName = dsBackingIndexName.replace("-ds-", "-ds2-");
+        otherDs2BackingIndexName = otherDsBackingIndexName.replace("-other-ds-", "-other-ds2-");
 
         IndexResponse indexResponse = client.prepareIndex("ds").setOpType(DocWriteRequest.OpType.CREATE).setSource(DOCUMENT_SOURCE).get();
         assertEquals(DocWriteResponse.Result.CREATED, indexResponse.getResult());
@@ -515,6 +517,48 @@ public void testRename() throws Exception {
         assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds").get(0).getWriteDataStream(), equalTo("other-ds"));
     }
 
+    public void testRenameWriteDataStream() throws Exception {
+        CreateSnapshotResponse createSnapshotResponse = client.admin()
+            .cluster()
+            .prepareCreateSnapshot(REPO, SNAPSHOT)
+            .setWaitForCompletion(true)
+            .setIndices("other-ds")
+            .setIncludeGlobalState(false)
+            .get();
+
+        RestStatus status = createSnapshotResponse.getSnapshotInfo().status();
+        assertEquals(RestStatus.OK, status);
+
+        client.admin()
+            .cluster()
+            .prepareRestoreSnapshot(REPO, SNAPSHOT)
+            .setWaitForCompletion(true)
+            .setIndices("other-ds")
+            .setRenamePattern("other-ds")
+            .setRenameReplacement("other-ds2")
+            .get();
+
+        GetDataStreamAction.Response ds = client.execute(
+            GetDataStreamAction.INSTANCE,
+            new GetDataStreamAction.Request(new String[] { "other-ds2" })
+        ).get();
+        assertEquals(1, ds.getDataStreams().size());
+        assertEquals(1, ds.getDataStreams().get(0).getDataStream().getIndices().size());
+        assertEquals(otherDs2BackingIndexName, ds.getDataStreams().get(0).getDataStream().getIndices().get(0).getName());
+
+        GetAliasesResponse getAliasesResponse = client.admin().indices().getAliases(new GetAliasesRequest("my-alias")).actionGet();
+        assertThat(getAliasesResponse.getDataStreamAliases().keySet(), containsInAnyOrder("ds", "other-ds", "other-ds2"));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds2").size(), equalTo(1));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds2").get(0).getName(), equalTo("my-alias"));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds2").get(0).getWriteDataStream(), equalTo("other-ds2"));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("ds").size(), equalTo(1));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("ds").get(0).getName(), equalTo("my-alias"));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("ds").get(0).getWriteDataStream(), equalTo("other-ds2"));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds").size(), equalTo(1));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds").get(0).getName(), equalTo("my-alias"));
+        assertThat(getAliasesResponse.getDataStreamAliases().get("other-ds").get(0).getWriteDataStream(), equalTo("other-ds2"));
+    }
+
     public void testBackingIndexIsNotRenamedWhenRestoringDataStream() {
         CreateSnapshotResponse createSnapshotResponse = client.admin()
             .cluster()