update to reflect no defaulting values

docs/reference/indices/aliases.asciidoc

@@ -326,7 +326,10 @@ POST /_aliases
 
 [IMPORTANT]
 =====================================
-`is_write_index` will default to `true` for an index that only has one alias which did not explicitly specify a value.
+Aliases that do not explicitly set `is_write_index: true` for an index, and
+only reference one index, will have that referenced index behave as if it is the write index
+until an additional index is referenced. At that point, there will be no write index and
+writes will be rejected.
 =====================================
 
 [float]

rest-api-spec/src/main/resources/rest-api-spec/test/indices.create/10_basic.yml

@@ -81,7 +81,7 @@
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
+  - is_false: test_index.aliases.test_alias.is_write_index
   - match: {test_index.aliases.test_blias.search_routing: b}
   - match: {test_index.aliases.test_blias.index_routing: b}
   - is_false: test_index.aliases.test_blias.filter

rest-api-spec/src/main/resources/rest-api-spec/test/indices.get_alias/10_basic.yml

@@ -27,10 +27,10 @@ setup:
   - do:
       indices.get_alias: {}
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
-  - match: {test_index_2.aliases.test_blias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_blias: {}}
   - match: {test_index_3.aliases: {}}
 
 ---
@@ -44,10 +44,10 @@ setup:
       indices.get_alias:
         name: _all
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
-  - match: {test_index_2.aliases.test_blias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_blias: {}}
   - is_false: test_index_3
 
 ---
@@ -61,10 +61,10 @@ setup:
       indices.get_alias:
         name: _all
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
-  - match: {test_index_2.aliases.test_blias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_blias: {}}
   - is_false: test_index_3
 
 ---
@@ -74,8 +74,8 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
   - is_false: test_index_2
 
 ---
@@ -88,10 +88,10 @@ setup:
       indices.get_alias:
         index: _all
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
-  - match: {test_index_2.aliases.test_blias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_blias: {}}
   - match: {myindex.aliases: {}}
 
 ---
@@ -104,10 +104,10 @@ setup:
       indices.get_alias:
         index: "*"
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
-  - match: {test_index_2.aliases.test_blias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_blias: {}}
   - match: {myindex.aliases: {}}
 
 ---
@@ -130,7 +130,7 @@ setup:
         index: test_index
         name:  test_alias
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2
 
@@ -142,8 +142,8 @@ setup:
         index: test_index
         name: _all
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
   - is_false: test_index_2
 
 ---
@@ -154,8 +154,8 @@ setup:
         index: test_index
         name: '*'
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
   - is_false: test_index_2
 
 ---
@@ -165,7 +165,7 @@ setup:
         index: test_index
         name: 'test_a*'
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2
 
@@ -177,8 +177,8 @@ setup:
         index: test_index
         name: 'test_alias,test_blias'
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index.aliases.test_blias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index.aliases.test_blias: {}}
   - is_false: test_index_2
 
 ---
@@ -188,8 +188,8 @@ setup:
       indices.get_alias:
         name: test_alias
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2.aliases.test_blias
 
@@ -201,8 +201,8 @@ setup:
         index: _all
         name: test_alias
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2.aliases.test_blias
 
@@ -214,8 +214,8 @@ setup:
         index: '*'
         name: test_alias
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2.aliases.test_blias
 
@@ -227,7 +227,7 @@ setup:
         index: '*2'
         name: test_alias
 
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
+  - match: {test_index_2.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_alias
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2.aliases.test_blias
@@ -240,8 +240,8 @@ setup:
         index: test_index,test_index_2
         name: test_alias
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
-  - match: {test_index_2.aliases.test_alias: { is_write_index: false }}
+  - match: {test_index.aliases.test_alias: {}}
+  - match: {test_index_2.aliases.test_alias: {}}
   - is_false: test_index.aliases.test_blias
   - is_false: test_index_2.aliases.test_blias
 
@@ -267,7 +267,7 @@ setup:
 
   - match: { 'status': 404 }
   - match: { 'error': 'alias [non-existent] missing' }
-  - match: { test_index.aliases.test_alias: { is_write_index: true } }
+  - match: { test_index.aliases.test_alias: { } }
 
 ---
 "Existent and non-existent aliases returns 404 and the existing alias":
@@ -279,7 +279,7 @@ setup:
 
   - match: { 'status': 404 }
   - match: { 'error': 'aliases [another-non-existent,non-existent] missing' }
-  - match: { test_index.aliases.test_alias: { is_write_index: true } }
+  - match: { test_index.aliases.test_alias: { } }
 
 ---
 "Getting alias on an non-existent index should return 404":

rest-api-spec/src/main/resources/rest-api-spec/test/indices.put_alias/10_basic.yml

@@ -26,7 +26,7 @@
       indices.get_alias:
         name: test_alias
 
-  - match: {test_index.aliases.test_alias: { is_write_index: true }}
+  - match: {test_index.aliases.test_alias: {}}
 
 ---
 "Can't create alias with invalid characters":

rest-api-spec/src/main/resources/rest-api-spec/test/indices.put_alias/all_path_options.yml

@@ -27,9 +27,9 @@ setup:
       indices.get_alias:
         name: alias
 
-  - match: {test_index1.aliases.alias: { is_write_index: true }}
+  - match: {test_index1.aliases.alias: {}}
 
-  - match: {test_index2.aliases.alias: { is_write_index: false }}
+  - match: {test_index2.aliases.alias: {}}
 
   - is_false: foo
 
@@ -45,9 +45,9 @@ setup:
       indices.get_alias:
         name: alias
 
-  - match: {test_index1.aliases.alias: { is_write_index: false }}
-  - match: {test_index2.aliases.alias: { is_write_index: false }}
-  - match: {foo.aliases.alias: { is_write_index: false }}
+  - match: {test_index1.aliases.alias: {}}
+  - match: {test_index2.aliases.alias: {}}
+  - match: {foo.aliases.alias: {}}
 
 ---
 "put alias in * index":
@@ -62,9 +62,9 @@ setup:
       indices.get_alias:
         name: alias
 
-  - match: {test_index1.aliases.alias: { is_write_index: false }}
-  - match: {test_index2.aliases.alias: { is_write_index: false }}
-  - match: {foo.aliases.alias: { is_write_index: false }}
+  - match: {test_index1.aliases.alias: {}}
+  - match: {test_index2.aliases.alias: {}}
+  - match: {foo.aliases.alias: {}}
 
 ---
 "put alias prefix* index":
@@ -77,8 +77,8 @@ setup:
       indices.get_alias:
         name: alias
 
-  - match: {test_index1.aliases.alias: { is_write_index: false }}
-  - match: {test_index2.aliases.alias: { is_write_index: false }}
+  - match: {test_index1.aliases.alias: {}}
+  - match: {test_index2.aliases.alias: {}}
   - is_false: foo
 
 ---
@@ -92,8 +92,8 @@ setup:
       indices.get_alias:
         name: alias
 
-  - match: {test_index1.aliases.alias: { is_write_index: false }}
-  - match: {test_index2.aliases.alias: { is_write_index: false }}
+  - match: {test_index1.aliases.alias: {}}
+  - match: {test_index2.aliases.alias: {}}
   - is_false: foo
 
 ---

rest-api-spec/src/main/resources/rest-api-spec/test/indices.update_aliases/10_basic.yml

@@ -34,7 +34,7 @@
         index: test_index
         name: test_alias
 
-  - match: {test_index.aliases.test_alias: {filter: { ids : { values: ["1", "2", "3"]}}, 'index_routing': 'routing_value', 'search_routing': 'routing_value', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {filter: { ids : { values: ["1", "2", "3"]}}, 'index_routing': 'routing_value', 'search_routing': 'routing_value'}}
 
 ---
 "Basic test for multiple aliases":
@@ -80,8 +80,8 @@
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias1: {'index_routing': 'routing_value', 'search_routing': 'routing_value', 'is_write_index': true }}
-  - match: {test_index.aliases.test_alias2: {'index_routing': 'routing_value', 'search_routing': 'routing_value', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias1: {'index_routing': 'routing_value', 'search_routing': 'routing_value'}}
+  - match: {test_index.aliases.test_alias2: {'index_routing': 'routing_value', 'search_routing': 'routing_value'}}
 
 ---
 "Remove alias":

rest-api-spec/src/main/resources/rest-api-spec/test/indices.update_aliases/20_routing.yml

@@ -19,7 +19,7 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'index_routing': 'routing', 'search_routing': 'routing', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'index_routing': 'routing', 'search_routing': 'routing'}}
 
 ---
 "Index Routing":
@@ -37,7 +37,7 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'index_routing': 'index_routing', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'index_routing': 'index_routing'}}
 
 ---
 "Search Routing":
@@ -55,7 +55,7 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'search_routing': 'search_routing', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'search_routing': 'search_routing'}}
 
 ---
 "Index, Default Routing":
@@ -74,7 +74,7 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'index_routing': 'index_routing', 'search_routing': 'routing', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'index_routing': 'index_routing', 'search_routing': 'routing'}}
 
 ---
 "Search, Default Routing":
@@ -93,7 +93,7 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'index_routing': 'routing', 'search_routing': 'search_routing', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'index_routing': 'routing', 'search_routing': 'search_routing'}}
 
 ---
 "Index, Search, Default Routing":
@@ -113,7 +113,7 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'index_routing': 'index_routing', 'search_routing': 'search_routing', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'index_routing': 'index_routing', 'search_routing': 'search_routing'}}
 
 ---
 "Numeric Routing":
@@ -131,5 +131,5 @@ setup:
       indices.get_alias:
         index: test_index
 
-  - match: {test_index.aliases.test_alias: {'index_routing': '5', 'search_routing': '5', 'is_write_index': true }}
+  - match: {test_index.aliases.test_alias: {'index_routing': '5', 'search_routing': '5'}}
 

server/src/main/java/org/elasticsearch/cluster/metadata/AliasOrIndex.java

@@ -154,7 +154,8 @@ void addIndex(IndexMetaData indexMetaData) {
         }
 
         public void computeAndValidateWriteIndex() {
-            List<IndexMetaData> writeIndices = referenceIndexMetaDatas.stream().filter(idxMeta -> Boolean.TRUE.equals(idxMeta.getAliases().get(aliasName)))
+            List<IndexMetaData> writeIndices = referenceIndexMetaDatas.stream()
+                .filter(idxMeta -> Boolean.TRUE.equals(idxMeta.getAliases().get(aliasName).writeIndex()))
                 .collect(Collectors.toList());
             if (writeIndices.size() == 1) {
                 writeIndex.set(writeIndices.get(0));

server/src/main/java/org/elasticsearch/cluster/metadata/MetaData.java

@@ -1076,7 +1076,7 @@ private SortedMap<String, AliasOrIndex> buildAliasAndIndexLookup() {
                 }
             }
             aliasAndIndexLookup.values().stream().filter(AliasOrIndex::isAlias)
-                .forEach(alias -> ((AliasOrIndex.Alias) alias).computeAndValidateWriteIndex();
+                .forEach(alias -> ((AliasOrIndex.Alias) alias).computeAndValidateWriteIndex());
             return aliasAndIndexLookup;
         }