update to not throw exception when step not recognized in runner, but throw in action

Author: talevy

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

@@ -185,7 +185,8 @@ static ClusterState moveClusterStateToStep(String indexName, ClusterState curren
 
         Step nextStep = stepRegistry.getStep(indexPolicySetting, nextStepKey);
         if (nextStep == null) {
-            throw new IllegalArgumentException("step [" + nextStepKey + "] with policy [" + indexPolicySetting + "] does not exist");
+            // stepRegistry may not be up-to-date with latest policies/steps in cluster-state
+            return currentState;
         }
 
         return IndexLifecycleRunner.moveClusterStateToNextStep(idxMeta.getIndex(), currentState, currentStepKey, nextStepKey, nowSupplier);

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

@@ -58,8 +58,12 @@ protected void masterOperation(Request request, ClusterState state, ActionListen
             new AckedClusterStateUpdateTask<Response>(request, listener) {
                 @Override
                 public ClusterState execute(ClusterState currentState) {
-                    return indexLifecycleService.moveClusterStateToStep(currentState, request.getIndex(), request.getCurrentStepKey(),
+                    ClusterState movedState = indexLifecycleService.moveClusterStateToStep(currentState, request.getIndex(), request.getCurrentStepKey(),
                         request.getNextStepKey());
+                    if (currentState == movedState) {
+                        throw new IllegalArgumentException("next step [" + request.getNextStepKey() + "] is not recognized");
+                    }
+                    return movedState;
                 }
 
                 @Override

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

@@ -674,12 +674,9 @@ public void testValidatedMoveClusterStateToNextStepInvalidNextStep() {
             .put(LifecycleSettings.LIFECYCLE_ACTION, currentStepKey.getAction())
             .put(LifecycleSettings.LIFECYCLE_STEP, currentStepKey.getName());
         ClusterState clusterState = buildClusterState(indexName, indexSettingsBuilder, Collections.emptyList());
-        IllegalArgumentException exception = expectThrows(IllegalArgumentException.class,
-            () -> IndexLifecycleRunner.moveClusterStateToStep(indexName, clusterState, currentStepKey,
-                nextStepKey, () -> now, stepRegistry));
-        assertThat(exception.getMessage(),
-            equalTo("step [{\"phase\":\"next_phase\",\"action\":\"next_action\",\"name\":\"next_step\"}] " +
-                "with policy [my_policy] does not exist"));
+        ClusterState newState = IndexLifecycleRunner.moveClusterStateToStep(indexName, clusterState, currentStepKey,
+                nextStepKey, () -> now, stepRegistry);
+        assertSame(newState, clusterState);
     }
 
     public void testMoveClusterStateToErrorStep() throws IOException {

x-pack/plugin/src/test/resources/rest-api-spec/test/index_lifecycle/20_move_to_step.yml

@@ -138,7 +138,7 @@ teardown:
             action: "invalid"
             name: "invalid"
   - match: { error.root_cause.0.type: "illegal_argument_exception" }
-  - match: { error.root_cause.0.reason: "step [{\"phase\":\"invalid\",\"action\":\"invalid\",\"name\":\"invalid\"}] with policy [my_moveable_timeseries_lifecycle] does not exist" }
+  - match: { error.root_cause.0.reason: "next step [{\"phase\":\"invalid\",\"action\":\"invalid\",\"name\":\"invalid\"}] is not recognized" }
 
   - do:
       acknowledge: true