Disallow type names to start with dots for new indices except for .percolator

This commit will disallow type names to start with dots for version 2 and later indices except for .percolator.

Closes #12560

core/src/main/java/org/elasticsearch/index/mapper/MapperService.java

@@ -272,8 +272,12 @@ public class MapperService extends AbstractIndexComponent  {
             if (Version.indexCreated(indexSettings).onOrAfter(Version.V_2_0_0_beta1) && mapper.type().equals(mapper.parentFieldMapper().type())) {
                 throw new IllegalArgumentException("The [_parent.type] option can't point to the same type");
             }
-            if (mapper.type().contains(".") && !PercolatorService.TYPE_NAME.equals(mapper.type())) {
+            if (typeNameStartsWithIllegalDot(mapper)) {
-                logger.warn("Type [{}] contains a '.', it is recommended not to include it within a type name", mapper.type());
+                if (Version.indexCreated(indexSettings).onOrAfter(Version.V_2_0_0_beta1)) {
+                    throw new IllegalArgumentException("mapping type name [" + mapper.type() + "] must not start with a '.'");
+                } else {
+                    logger.warn("Type [{}] starts with a '.', it is recommended not to start a type name with a '.'", mapper.type());
+                }
             }
             // we can add new field/object mappers while the old ones are there
             // since we get new instances of those, and when we remove, we remove
@@ -315,6 +319,10 @@ public class MapperService extends AbstractIndexComponent  {
         }
     }
 
+    private boolean typeNameStartsWithIllegalDot(DocumentMapper mapper) {
+        return mapper.type().startsWith(".") && !PercolatorService.TYPE_NAME.equals(mapper.type());
+    }
+
     private boolean assertSerialization(DocumentMapper mapper) {
         // capture the source now, it may change due to concurrent parsing
         final CompressedXContent mappingSource = mapper.mappingSource();

core/src/test/java/org/elasticsearch/index/mapper/MapperServiceTest.java

@@ -0,0 +1,49 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.index.mapper;
+
+import org.elasticsearch.test.ElasticsearchSingleNodeTest;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.Matchers.hasToString;
+
+public class MapperServiceTest extends ElasticsearchSingleNodeTest {
+    @Rule
+    public ExpectedException expectedException = ExpectedException.none();
+
+    @Test
+    public void testTypeNameStartsWithIllegalDot() {
+        expectedException.expect(MapperParsingException.class);
+        expectedException.expect(hasToString(containsString("mapping type name [.test-type] must not start with a '.'")));
+        String index = "test-index";
+        String type = ".test-type";
+        String field = "field";
+        client()
+                .admin()
+                .indices()
+                .prepareCreate(index)
+                .addMapping(type, field, "type=string")
+                .execute()
+                .actionGet();
+    }
+}

docs/reference/migration/migrate_2_0.asciidoc

@@ -192,6 +192,7 @@ A `RoutingMissingException` is now thrown instead.
 
 * The setting `index.mapping.allow_type_wrapper` has been removed.  Documents should always be sent without the type as the root element.
 * The delete mappings API has been removed. Mapping types can no longer be deleted.
+* Mapping type names can no longer start with dots.
 * The `ignore_conflicts` option of the put mappings API has been removed. Conflicts can't be ignored anymore.
 * The `binary` field does not support the `compress` and `compress_threshold` options anymore.