IndexClosedException to return 400 rather than 403 (#25752)

403 can be confused with security. If an API doesn't support working against closed indices and closed indices are referred to in a request, that is a bad request, hence 400 is more appropriate.

core/src/main/java/org/elasticsearch/indices/IndexClosedException.java

@@ -42,6 +42,6 @@ public class IndexClosedException extends ElasticsearchException {
 
     @Override
     public RestStatus status() {
-        return RestStatus.FORBIDDEN;
+        return RestStatus.BAD_REQUEST;
     }
 }

docs/reference/migration/migrate_6_0/rest.asciidoc

@@ -107,8 +107,15 @@ $ curl -v -XPOST 'localhost:9200/my_index/_settings'
 * Connection #0 to host localhost left intact
 --------------------------------------------
 
-==== Dissallow using `_cache` and `_cache_key`
+==== Disallow using `_cache` and `_cache_key`
 
 The `_cache` and `_cache_key` options in queries have been deprecated since version 2.0.0 and
 have been ignored since then, issuing a deprecation warning. These options have now been completely
 removed, so using them now will throw an error.
+
+==== IndexClosedException to return 400 status code
+
+An `IndexClosedException` is returned whenever an api that doesn't support
+closed indices (e.g. search) is called passing closed indices as parameters
+and `ignore_unavailable` is set to `false`. The response status code returned
+in such case changed from `403` to `400`

rest-api-spec/src/main/resources/rest-api-spec/test/cat.segments/10_basic.yml

@@ -86,6 +86,10 @@
 ---
 "Test cat segments on closed index behaviour":
 
+  - skip:
+      version: " - 5.99.99"
+      reason:  status code  on closed indices changed in 6.0.0 from 403 to 400
+
   - do:
       indices.create:
         index: index1
@@ -99,7 +103,7 @@
         index: index1
 
   - do:
-      catch: forbidden
+      catch: request
       cat.segments:
         index: index1
 

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

@@ -1,5 +1,9 @@
 ---
 "Basic test for index open/close":
+  - skip:
+      version: " - 5.99.99"
+      reason:  status code  on closed indices changed in 6.0.0 from 403 to 400
+
   - do:
       indices.create:
         index: test_index
@@ -16,7 +20,7 @@
         index: test_index
 
   - do:
-      catch: forbidden
+      catch: request
       search:
         index: test_index
 

rest-api-spec/src/main/resources/rest-api-spec/test/indices.open/20_multiple_indices.yml

@@ -23,12 +23,16 @@ setup:
 
 ---
 "All indices":
+  - skip:
+      version: " - 5.99.99"
+      reason:  status code  on closed indices changed in 6.0.0 from 403 to 400
+
   - do:
       indices.close:
         index: _all
 
   - do:
-      catch: forbidden
+      catch: request
       search:
         index: test_index2
 
@@ -46,12 +50,16 @@ setup:
 
 ---
 "Trailing wildcard":
+  - skip:
+      version: " - 5.99.99"
+      reason:  status code  on closed indices changed in 6.0.0 from 403 to 400
+
   - do:
       indices.close:
         index: test_*
 
   - do:
-      catch: forbidden
+      catch: request
       search:
         index: test_index2
 
@@ -69,12 +77,16 @@ setup:
 
 ---
 "Only wildcard":
+  - skip:
+      version: " - 5.99.99"
+      reason:  status code  on closed indices changed in 6.0.0 from 403 to 400
+
   - do:
       indices.close:
         index: '*'
 
   - do:
-      catch: forbidden
+      catch: request
       search:
         index: test_index3
 

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

@@ -43,6 +43,9 @@
 
 ---
 "closed segments test":
+  - skip:
+      version: " - 5.99.99"
+      reason:  status code  on closed indices changed in 6.0.0 from 403 to 400
 
   - do:
       indices.create:
@@ -63,7 +66,7 @@
         index: index1
 
   - do:
-      catch: forbidden
+      catch: request
       indices.segments:
           index: index1