Make isHidden a primitive when finding v2 templates (#55408) (#55433)

isHidden was a `Boolean` in order to treat a special case identified
with V1 templates where if the create index request didn't specify if
the index should be hidden or not (ie. isHidden was `null`) but the
index matched a template that specified the `index.hidden` setting we
needed to remove the global templates from the templates we'll apply to
the new index (note: this is important with V1 templates as inheritance
is supported).

With V2 templates we match only one template with an index so the
equivalent check did not need to exist (we added a sanity check in
https://github.com/elastic/elasticsearch/pull/55015 where we make sure
we don't apply an invalid global template - one that specifes the
`index.hidden` setting, but this is a check we make irrespective of the
user specifying or not if the index should be hidden)

This commit makes `isHidden` when matching V2 templates a boolean
primitive, eliminating the need for the `null` state to exist. Note that
some methods which use the matching V2 templates still work with a
`Boolean` object `isHidden` attribute as they are also matching the V1
templates. These methods will pass in `false` instead of `null` when
finding the V2 templates.

(cherry picked from commit c5b923afec911c6ae8fc5179e65ae6bf55dcc5f1)
Signed-off-by: Andrei Dan <andrei.dan@elastic.co>

server/src/main/java/org/elasticsearch/action/admin/indices/rollover/MetadataRolloverService.java

@@ -177,7 +177,7 @@ public class MetadataRolloverService {
             }
         }
 
-        final String matchedV2Template = findV2Template(metadata, rolloverIndexName, isHidden);
+        final String matchedV2Template = findV2Template(metadata, rolloverIndexName, isHidden == null ? false : isHidden);
         if (matchedV2Template != null) {
             List<Map<String, AliasMetadata>> aliases = MetadataIndexTemplateService.resolveAliases(metadata, matchedV2Template);
             for (Map<String, AliasMetadata> aliasConfig : aliases) {

server/src/main/java/org/elasticsearch/action/bulk/TransportBulkAction.java

@@ -313,7 +313,7 @@ public class TransportBulkAction extends HandledTransportAction<BulkRequest, Bul
                 // the index does not exist yet (and this is a valid request), so match index
                 // templates to look for pipelines in either a matching V2 template (which takes
                 // precedence), or if a V2 template does not match, any V1 templates
-                String v2Template = MetadataIndexTemplateService.findV2Template(metadata, indexRequest.index(), null);
+                String v2Template = MetadataIndexTemplateService.findV2Template(metadata, indexRequest.index(), false);
                 if (v2Template != null) {
                     Settings settings = MetadataIndexTemplateService.resolveSettings(metadata, v2Template);
                     if (defaultPipeline == null && IndexSettings.DEFAULT_PIPELINE.exists(settings)) {

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

@@ -324,7 +324,7 @@ public class MetadataCreateIndexService {
 
             // Check to see if a v2 template matched
             final String v2Template = MetadataIndexTemplateService.findV2Template(currentState.metadata(),
-                request.index(), isHiddenFromRequest);
+                request.index(), isHiddenFromRequest == null ? false : isHiddenFromRequest);
 
             if (v2Template != null) {
                 // If a v2 template was found, it takes precedence over all v1 templates, so create

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

@@ -664,19 +664,18 @@ public class MetadataIndexTemplateService {
      * the event that no templates are matched, {@code null} is returned.
      */
     @Nullable
-    public static String findV2Template(Metadata metadata, String indexName, @Nullable Boolean isHidden) {
+    public static String findV2Template(Metadata metadata, String indexName, boolean isHidden) {
         final Predicate<String> patternMatchPredicate = pattern -> Regex.simpleMatch(pattern, indexName);
         final Map<IndexTemplateV2, String> matchedTemplates = new HashMap<>();
         for (Map.Entry<String, IndexTemplateV2> entry : metadata.templatesV2().entrySet()) {
             final String name = entry.getKey();
             final IndexTemplateV2 template = entry.getValue();
-            if (isHidden == null || isHidden == Boolean.FALSE) {
+            if (isHidden == false) {
                 final boolean matched = template.indexPatterns().stream().anyMatch(patternMatchPredicate);
                 if (matched) {
                     matchedTemplates.put(template, name);
                 }
             } else {
-                assert isHidden == Boolean.TRUE;
                 final boolean isNotMatchAllTemplate = template.indexPatterns().stream().noneMatch(Regex::isMatchAllPattern);
                 if (isNotMatchAllTemplate) {
                     if (template.indexPatterns().stream().anyMatch(patternMatchPredicate)) {

server/src/test/java/org/elasticsearch/action/admin/indices/rollover/MetadataRolloverServiceTests.java

@@ -324,7 +324,7 @@ public class MetadataRolloverServiceTests extends ESTestCase {
         MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, Boolean.TRUE);
         // not hidden will throw
         final IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () ->
-            MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, randomFrom(Boolean.FALSE, null)));
+            MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, false));
         assertThat(ex.getMessage(), containsString("index template [test-template]"));
     }
 
@@ -344,7 +344,7 @@ public class MetadataRolloverServiceTests extends ESTestCase {
         MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, Boolean.TRUE);
         // not hidden will throw
         final IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () ->
-            MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, randomFrom(Boolean.FALSE, null)));
+            MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, false));
         assertThat(ex.getMessage(), containsString("index template [test-template]"));
     }
 
@@ -367,7 +367,7 @@ public class MetadataRolloverServiceTests extends ESTestCase {
         MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, Boolean.TRUE);
         // not hidden will throw
         final IllegalArgumentException ex = expectThrows(IllegalArgumentException.class, () ->
-            MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, randomFrom(Boolean.FALSE, null)));
+            MetadataRolloverService.checkNoDuplicatedAliasInIndexTemplate(metadata, indexName, aliasName, false));
         assertThat(ex.getMessage(), containsString("index template [test-template]"));
     }
 

server/src/test/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateServiceTests.java

@@ -490,7 +490,7 @@ public class MetadataIndexTemplateServiceTests extends ESSingleNodeTestCase {
     public void testFindV2Templates() throws Exception {
         final MetadataIndexTemplateService service = getMetadataIndexTemplateService();
         ClusterState state = ClusterState.EMPTY_STATE;
-        assertNull(MetadataIndexTemplateService.findV2Template(state.metadata(), "index", randomBoolean() ? null : randomBoolean()));
+        assertNull(MetadataIndexTemplateService.findV2Template(state.metadata(), "index", randomBoolean()));
 
         ComponentTemplate ct = ComponentTemplateTests.randomInstance();
         state = service.addComponentTemplate(state, true, "ct", ct);
@@ -499,7 +499,7 @@ public class MetadataIndexTemplateServiceTests extends ESSingleNodeTestCase {
         IndexTemplateV2 it2 = new IndexTemplateV2(Collections.singletonList("in*"), null, Collections.singletonList("ct"), 10L, 2L, null);
         state = service.addIndexTemplateV2(state, true, "my-template2", it2);
 
-        String result = MetadataIndexTemplateService.findV2Template(state.metadata(), "index", randomBoolean() ? null : randomBoolean());
+        String result = MetadataIndexTemplateService.findV2Template(state.metadata(), "index", randomBoolean());
 
         assertThat(result, equalTo("my-template2"));
     }
@@ -531,7 +531,7 @@ public class MetadataIndexTemplateServiceTests extends ESSingleNodeTestCase {
                 new IndexTemplateV2Metadata(org.elasticsearch.common.collect.Map.of("invalid_global_template", invalidGlobalTemplate)))
                 .build();
 
-            MetadataIndexTemplateService.findV2Template(invalidGlobalTemplateMetadata, "index-name", null);
+            MetadataIndexTemplateService.findV2Template(invalidGlobalTemplateMetadata, "index-name", false);
             fail("expecting an exception as the matching global template is invalid");
         } catch (IllegalStateException e) {
             assertThat(e.getMessage(), is("global index template [invalid_global_template], composed of component templates [ct] " +