Disallow : in cluster and index/alias names (#26247)

We use `:` for cross-cluster search (eg `cluster:index`), therefore, we should
not allow the ambiguity when allowing cluster or index names.

Relates to #23892

Author: dakrone

core/src/main/java/org/elasticsearch/cluster/ClusterName.java

@@ -22,6 +22,8 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.logging.DeprecationLogger;
+import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 
@@ -30,10 +32,15 @@
 
 public class ClusterName implements Writeable {
 
+    private static final DeprecationLogger deprecationLogger = new DeprecationLogger(Loggers.getLogger(ClusterName.class));
+
     public static final Setting<ClusterName> CLUSTER_NAME_SETTING = new Setting<>("cluster.name", "elasticsearch", (s) -> {
         if (s.isEmpty()) {
             throw new IllegalArgumentException("[cluster.name] must not be empty");
         }
+        if (s.contains(":")) {
+            deprecationLogger.deprecated("[cluster.name] containing ':' is deprecated and will not be supported in Elasticsearch 7.0+");
+        }
         return new ClusterName(s);
     }, Setting.Property.NodeScope);
 

core/src/main/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexService.java

@@ -56,6 +56,8 @@
 import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.io.PathUtils;
+import org.elasticsearch.common.logging.DeprecationLogger;
+import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Settings;
@@ -106,6 +108,8 @@
  */
 public class MetaDataCreateIndexService extends AbstractComponent {
 
+    private static final DeprecationLogger deprecationLogger = new DeprecationLogger(Loggers.getLogger(MetaDataCreateIndexService.class));
+
     public static final int MAX_INDEX_NAME_BYTES = 255;
 
     private final ClusterService clusterService;
@@ -165,6 +169,10 @@ public static void validateIndexOrAliasName(String index, BiFunction<String, Str
         if (index.contains("#")) {
             throw exceptionCtor.apply(index, "must not contain '#'");
         }
+        if (index.contains(":")) {
+            deprecationLogger.deprecated("index or alias name [" + index +
+                            "] containing ':' is deprecated and will not be supported in Elasticsearch 7.0+");
+        }
         if (index.charAt(0) == '_' || index.charAt(0) == '-' || index.charAt(0) == '+') {
             throw exceptionCtor.apply(index, "must not start with '_', '-', or '+'");
         }

core/src/test/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexServiceTests.java

@@ -212,6 +212,9 @@ public void testValidateIndexName() throws Exception {
 
         validateIndexName("..", "must not be '.' or '..'");
 
+        MetaDataCreateIndexService.validateIndexName("foo:bar", ClusterState.builder(ClusterName.CLUSTER_NAME_SETTING
+                        .getDefault(Settings.EMPTY)).build());
+        assertWarnings("index or alias name [foo:bar] containing ':' is deprecated and will not be supported in Elasticsearch 7.0+");
     }
 
     private void validateIndexName(String indexName, String errorMessage) {