render non-ElasticsearchException in ILM (#31284)

ILM was rendering exceptions using the exception helper that
basically ignores simply rendering non-elasticsearch exceptions when
no details are desired. This commit updates the method used to still be
a rather simple rendering of the exception. The rendering lacks
all the causes, but does a sufficient job in rendering the top-level
message for one of our most expected exceptions... IllegalArgumentException

Author: talevy

x-pack/plugin/index-lifecycle/src/main/java/org/elasticsearch/xpack/indexlifecycle/IndexLifecycleRunner.java

@@ -196,7 +196,7 @@ static ClusterState moveClusterStateToErrorStep(Index index, ClusterState cluste
         IndexMetaData idxMeta = clusterState.getMetaData().index(index);
         XContentBuilder causeXContentBuilder = JsonXContent.contentBuilder();
         causeXContentBuilder.startObject();
-        ElasticsearchException.generateFailureXContent(causeXContentBuilder, ToXContent.EMPTY_PARAMS, cause, false);
+        ElasticsearchException.generateThrowableXContent(causeXContentBuilder, ToXContent.EMPTY_PARAMS, cause);
         causeXContentBuilder.endObject();
         Settings.Builder indexSettings = moveIndexSettingsToNextStep(idxMeta.getSettings(), currentStep,
                 new StepKey(currentStep.getPhase(), currentStep.getAction(), ErrorStep.NAME), nowSupplier)

x-pack/plugin/index-lifecycle/src/test/java/org/elasticsearch/xpack/indexlifecycle/IndexLifecycleRunnerTests.java

@@ -693,8 +693,15 @@ public void testMoveClusterStateToErrorStep() throws IOException {
                         .put(LifecycleSettings.LIFECYCLE_ACTION, currentStep.getAction())
                         .put(LifecycleSettings.LIFECYCLE_STEP, currentStep.getName()));
         Index index = clusterState.metaData().index(indexName).getIndex();
+
         ClusterState newClusterState = IndexLifecycleRunner.moveClusterStateToErrorStep(index, clusterState, currentStep, cause, () -> now);
-        assertClusterStateOnErrorStep(clusterState, index, currentStep, newClusterState, cause, now);
+        assertClusterStateOnErrorStep(clusterState, index, currentStep, newClusterState, now,
+            "{\"type\":\"exception\",\"reason\":\"THIS IS AN EXPECTED CAUSE\"}");
+
+        cause = new IllegalArgumentException("non elasticsearch-exception");
+        newClusterState = IndexLifecycleRunner.moveClusterStateToErrorStep(index, clusterState, currentStep, cause, () -> now);
+        assertClusterStateOnErrorStep(clusterState, index, currentStep, newClusterState, now,
+            "{\"type\":\"illegal_argument_exception\",\"reason\":\"non elasticsearch-exception\"}");
     }
 
     public void testMoveClusterStateToFailedStep() {
@@ -966,13 +973,8 @@ public static void assertClusterStateOnNextStep(ClusterState oldClusterState, In
         assertEquals("", LifecycleSettings.LIFECYCLE_STEP_INFO_SETTING.get(newIndexSettings));
     }
 
-    private void assertClusterStateOnErrorStep(ClusterState oldClusterState, Index index, StepKey currentStep, ClusterState newClusterState,
-            Exception cause, long now) throws IOException {
-        XContentBuilder causeXContentBuilder = JsonXContent.contentBuilder();
-        causeXContentBuilder.startObject();
-        ElasticsearchException.generateFailureXContent(causeXContentBuilder, ToXContent.EMPTY_PARAMS, cause, false);
-        causeXContentBuilder.endObject();
-        String expectedCauseValue = BytesReference.bytes(causeXContentBuilder).utf8ToString();
+    private void assertClusterStateOnErrorStep(ClusterState oldClusterState, Index index, StepKey currentStep,
+                                               ClusterState newClusterState, long now, String expectedCauseValue) throws IOException {
         assertNotSame(oldClusterState, newClusterState);
         MetaData newMetadata = newClusterState.metaData();
         assertNotSame(oldClusterState.metaData(), newMetadata);

x-pack/plugin/index-lifecycle/src/test/java/org/elasticsearch/xpack/indexlifecycle/MoveToErrorStepUpdateTaskTests.java

@@ -68,7 +68,7 @@ public void testExecuteSuccessfullyMoved() throws IOException {
 
         XContentBuilder causeXContentBuilder = JsonXContent.contentBuilder();
         causeXContentBuilder.startObject();
-        ElasticsearchException.generateFailureXContent(causeXContentBuilder, ToXContent.EMPTY_PARAMS, cause, false);
+        ElasticsearchException.generateThrowableXContent(causeXContentBuilder, ToXContent.EMPTY_PARAMS, cause);
         causeXContentBuilder.endObject();
         String expectedCauseValue = BytesReference.bytes(causeXContentBuilder).utf8ToString();
         assertThat(LifecycleSettings.LIFECYCLE_STEP_INFO_SETTING.get(newState.metaData().index(index).getSettings()),