Consistent Indices API: Returning empty json instead of 404

If an index exists, but a single warmer/setting/alias/type is missing
return an empty JSON instead of an 404

Relates elastic#4071

rest-api-spec/test/indices.delete_alias/10_basic.yaml

@@ -25,7 +25,8 @@
         name: testali
 
   - do:
-      catch: missing
       indices.get_alias:
         index: testind
         name:  testali
+
+  - match: { '': {}}

rest-api-spec/test/indices.get_alias/10_basic.yaml

@@ -94,3 +94,33 @@ setup:
   - match: {test_index.aliases.test_alias: {}}
   - match: {test_index.aliases.test_blias: {}}
   - match: {test_index_2.aliases.test_alias_2: {}}
+
+---
+"Getting a non-existent alias on an existing index should return an empty body":
+
+  - do:
+      indices.get_alias:
+        index: test_index
+        name: non-existent
+
+  - match: { '': {}}
+
+---
+"Getting an existent and non-existent alias should return the existent and no data about the non-existent alias":
+
+  - do:
+      indices.get_alias:
+        index: test_index
+        name: test_alias,non-existent
+
+  - match: {test_index.aliases.test_alias: {}}
+  - is_false: test_index.alias.non-existent
+
+---
+"Getting warmer on an non-existent index should return 404":
+
+  - do:
+      catch: missing
+      indices.get_alias:
+        index: non-existent
+        name: foo

rest-api-spec/test/indices.get_mapping/10_basic.yaml

@@ -94,3 +94,33 @@ setup:
   - match: {test_idx.test_type.properties.text.type:       string}
   - match: {test_idx.test_type.properties.text.analyzer:   keyword}
 
+---
+"Getting a non-existent mapping on an existing index should return an empty body":
+
+  - do:
+      indices.get_mapping:
+        index: test_index
+        type: non-existent
+
+# match: {} does not work, so I just make sure the response is empty and not a 404
+  - is_false: test_index
+
+---
+"Getting an existent and non-existent mapping type should return the existing type and no data about the non-existent type":
+
+  - do:
+      indices.get_mapping:
+        index: test_index
+        type: test_type,non-existent
+
+  - match: {test_index.test_type.properties.text.type:     string}
+  - is_false: test_index.non-existent
+
+---
+"Getting mapping on an non-existent index should return 404":
+
+  - do:
+      catch: missing
+      indices.get_mapping:
+        index: non-existent
+        type: whatever

rest-api-spec/test/indices.get_mapping/20_missing_type.yaml

@@ -1,5 +1,5 @@
 ---
-"Raise 404 when type doesn't exist":
+"Return empty response when type doesn't exist":
   - do:
         indices.create:
           index: test_index
@@ -12,8 +12,8 @@
                       analyzer: whitespace
 
   - do:
-      catch: missing
       indices.get_mapping:
         index: test_index
         type: not_test_type
-
+
+  - match: { '': {}}

rest-api-spec/test/indices.get_settings/10_basic.yaml

@@ -94,3 +94,33 @@ setup:
   - is_false: test-index-2.settings.index.number_of_shards
   - match: { test-index-2.settings.index.refresh_interval: "10m" }
 
+---
+"Getting a non-existent setting on an existing index should return an empty body":
+
+  - do:
+      indices.get_settings:
+        index: test-index
+        name: non-existent
+
+  - match: { '': {}}
+
+---
+"Getting an existent and non-existent setting should return the existent and no data about the non-existing setting":
+
+  - do:
+      indices.get_settings:
+        index: test-index
+        name: index.number_of_replicas,non-existent
+
+  - match: { test-index.settings.index.number_of_replicas: "3" }
+  - is_false: test-index.settings.non-existent
+
+---
+"Getting setting on an non-existent index should return 404":
+
+  - do:
+      catch: missing
+      indices.get_settings:
+        index: non-existent
+        name: foo
+

rest-api-spec/test/indices.put_warmer/10_basic.yaml

@@ -12,12 +12,6 @@ setup:
       cluster.health:
         wait_for_status: yellow
 
-  - do:
-      catch: missing
-      indices.get_warmer:
-        index: test_index
-        name: test_warmer
-
   - do:
       indices.put_warmer:
         index: test_idx
@@ -49,10 +43,11 @@ setup:
         name: test_warmer
 
   - do:
-      catch: missing
       indices.get_warmer:
         index: test_index
         name: test_warmer
+# match: {} does not work, so I just make sure the response is empty and not a 404
+  - is_false: test_index
 
 ---
 "Getting warmers for several indices should work using *":
@@ -98,3 +93,33 @@ setup:
   - match: {test_index.warmers.test_warmer.source.query.match_all: {}}
   - match: {test_idx.warmers.test_warmer2.source.query.match_all: {}}
 
+---
+"Getting a non-existent warmer on an existing index should return an empty body":
+
+  - do:
+      indices.get_warmer:
+        index: test_index
+        name: non-existent
+
+  - match: { '': {}}
+
+---
+"Getting an existent and non-existent warmer should return the existent and no data about the non-existent warmer":
+
+  - do:
+      indices.get_warmer:
+        index: test_index
+        name: test_warmer,non-existent
+
+  - match: {test_index.warmers.test_warmer.source.query.match_all: {}}
+  - is_false: test_index.warmers.non-existent
+
+--- 
+"Getting warmer on an non-existent index should return 404":
+
+  - do:
+      catch: missing
+      indices.get_warmer:
+        index: non-existent
+        name: foo
+

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

@@ -368,9 +368,8 @@ public ImmutableOpenMap<String, ImmutableOpenMap<String, MappingMetaData>> findM
                         filteredMappings.put(cursor.key, cursor.value);
                     }
                 }
-                if (!filteredMappings.isEmpty()) {
-                    indexMapBuilder.put(index, filteredMappings.build());
-                }
+                // returning empty mappings help to differentiate between non-existing and indices without mapping for this type
+                indexMapBuilder.put(index, filteredMappings.build());
             }
         }
         return indexMapBuilder.build();

src/main/java/org/elasticsearch/rest/action/admin/indices/alias/get/RestGetAliasesAction.java

@@ -68,7 +68,11 @@ public void handleRequest(final RestRequest request, final RestChannel channel)
             public void onResponse(GetAliasesResponse response) {
                 try {
                     XContentBuilder builder = RestXContentBuilder.restContentBuilder(request);
-                    if (response.getAliases().isEmpty()) {
+                    // empty body, if indices were specified but no aliases were
+                    if (indices.length > 0 && response.getAliases().isEmpty()) {
+                        channel.sendResponse(new XContentRestResponse(request, OK, RestXContentBuilder.emptyBuilder(request)));
+                        return;
+                    } else if (response.getAliases().isEmpty()) {
                         String message = String.format(Locale.ROOT, "alias [%s] missing", toNamesString(getAliasesRequest.aliases()));
                         builder.startObject()
                                 .field("error", message)

src/main/java/org/elasticsearch/rest/action/admin/indices/mapping/get/RestGetMappingAction.java

@@ -89,6 +89,9 @@ public void onResponse(GetMappingsResponse response) {
                     }
 
                     for (ObjectObjectCursor<String, ImmutableOpenMap<String, MappingMetaData>> indexEntry : mappingsByIndex) {
+                        if (indexEntry.value.size() == 0) {
+                            continue;
+                        }
                         builder.startObject(indexEntry.key, XContentBuilder.FieldCaseConversion.NONE);
                         for (ObjectObjectCursor<String, MappingMetaData> typeEntry : indexEntry.value) {
                             builder.field(typeEntry.key);

src/main/java/org/elasticsearch/rest/action/admin/indices/settings/RestGetSettingsAction.java

@@ -62,19 +62,21 @@ public void handleRequest(final RestRequest request, final RestChannel channel)
             @Override
             public void onResponse(GetSettingsResponse getSettingsResponse) {
                 try {
-                    boolean foundAny = false;
                     XContentBuilder builder = RestXContentBuilder.restContentBuilder(request);
                     builder.startObject();
                     for (ObjectObjectCursor<String, Settings> cursor : getSettingsResponse.getIndexToSettings()) {
+                        // no settings, jump over it to shorten the response data
+                        if (cursor.value.getAsMap().size() == 0) {
+                            continue;
+                        }
                         builder.startObject(cursor.key, XContentBuilder.FieldCaseConversion.NONE);
-                        foundAny = true;
                         builder.startObject(Fields.SETTINGS);
                         cursor.value.toXContent(builder, request);
                         builder.endObject();
                         builder.endObject();
                     }
                     builder.endObject();
-                    channel.sendResponse(new XContentRestResponse(request, foundAny ? OK : NOT_FOUND, builder));
+                    channel.sendResponse(new XContentRestResponse(request, OK, builder));
                 } catch (IOException e) {
                     onFailure(e);
                 }

src/main/java/org/elasticsearch/rest/action/admin/indices/warmer/get/RestGetWarmerAction.java

@@ -71,7 +71,7 @@ public void handleRequest(final RestRequest request, final RestChannel channel)
             public void onResponse(GetWarmersResponse response) {
                 try {
                     if (indices.length > 0 && response.warmers().isEmpty()) {
-                        channel.sendResponse(new XContentThrowableRestResponse(request, new IndexMissingException(new Index(indices[0]))));
+                        channel.sendResponse(new XContentRestResponse(request, OK, RestXContentBuilder.emptyBuilder(request)));
                         return;
                     }
 

src/main/java/org/elasticsearch/rest/action/support/RestXContentBuilder.java

@@ -67,6 +67,10 @@ public static XContentBuilder restContentBuilder(RestRequest request, @Nullable
         return builder;
     }
 
+    public static XContentBuilder emptyBuilder(RestRequest request) throws IOException {
+        return restContentBuilder(request, request.hasContent() ? request.content() : null).startObject().endObject();
+    }
+
     /**
      * Directly writes the source to the output builder
      */