Include component templates in retention validaiton (#109779)

We shouldn't disregard a component template's lifecycle
configuration if the index template has one during retention
validation.

Author: nielsbauman

docs/changelog/109779.yaml

@@ -0,0 +1,5 @@
+pr: 109779
+summary: Include component templates in retention validaiton
+area: Data streams
+type: bug
+issues: []

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

@@ -805,9 +805,7 @@ static void validateLifecycle(
         ComposableIndexTemplate template,
         @Nullable DataStreamGlobalRetention globalRetention
     ) {
-        DataStreamLifecycle lifecycle = template.template() != null && template.template().lifecycle() != null
-            ? template.template().lifecycle()
-            : resolveLifecycle(template, metadata.componentTemplates());
+        DataStreamLifecycle lifecycle = resolveLifecycle(template, metadata.componentTemplates());
         if (lifecycle != null) {
             if (template.getDataStreamTemplate() == null) {
                 throw new IllegalArgumentException(

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

@@ -191,6 +191,48 @@ public void testValidateLifecycleIndexTemplateWithWarning() {
         );
     }
 
+    /**
+     * Make sure we still take into account component templates during validation (and not just the index template).
+     */
+    public void testValidateLifecycleComponentTemplateWithWarning() {
+        ThreadContext threadContext = new ThreadContext(Settings.EMPTY);
+        HeaderWarning.setThreadContext(threadContext);
+        TimeValue defaultRetention = randomTimeValue(2, 100, TimeUnit.DAYS);
+        MetadataIndexTemplateService.validateLifecycle(
+            Metadata.builder()
+                .componentTemplates(
+                    Map.of(
+                        "component-template",
+                        new ComponentTemplate(
+                            new Template(
+                                null,
+                                null,
+                                null,
+                                new DataStreamLifecycle(
+                                    new DataStreamLifecycle.Retention(randomTimeValue(2, 100, TimeUnit.DAYS)),
+                                    null,
+                                    null
+                                )
+                            ),
+                            null,
+                            null
+                        )
+                    )
+                )
+                .build(),
+            randomAlphaOfLength(10),
+            ComposableIndexTemplate.builder()
+                .template(new Template(null, null, null, DataStreamLifecycle.DEFAULT))
+                .dataStreamTemplate(new ComposableIndexTemplate.DataStreamTemplate())
+                .indexPatterns(List.of(randomAlphaOfLength(10)))
+                .componentTemplates(List.of("component-template"))
+                .build(),
+            new DataStreamGlobalRetention(defaultRetention, null)
+        );
+        Map<String, List<String>> responseHeaders = threadContext.getResponseHeaders();
+        assertThat(responseHeaders.size(), is(0));
+    }
+
     public void testValidateLifecycleInComponentTemplate() throws Exception {
         IndicesService indicesService = mock(IndicesService.class);
         IndexService indexService = mock(IndexService.class);