Replace OpenFollowerIndexStep with OpenIndexStep (#67254)

Author: andreidan

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ilm/OpenFollowerIndexStep.java

@@ -32,6 +32,7 @@ public final class UnfollowAction implements LifecycleAction {
 
     public static final String NAME = "unfollow";
     public static final String CCR_METADATA_KEY = "ccr";
+    static final String OPEN_FOLLOWER_INDEX_STEP_NAME = "open-follower-index";
 
     public UnfollowAction() {}
 
@@ -42,15 +43,17 @@ public List<Step> toSteps(Client client, String phase, StepKey nextStepKey) {
         StepKey pauseFollowerIndex = new StepKey(phase, NAME, PauseFollowerIndexStep.NAME);
         StepKey closeFollowerIndex = new StepKey(phase, NAME, CloseFollowerIndexStep.NAME);
         StepKey unfollowFollowerIndex = new StepKey(phase, NAME, UnfollowFollowerIndexStep.NAME);
-        StepKey openFollowerIndex = new StepKey(phase, NAME, OpenFollowerIndexStep.NAME);
+        // maintaining the `open-follower-index` here (as opposed to {@link OpenIndexStep#NAME}) for BWC reasons (in case any managed
+        // index is in the `open-follower-index` step at upgrade time
+        StepKey openFollowerIndex = new StepKey(phase, NAME, OPEN_FOLLOWER_INDEX_STEP_NAME);
         StepKey waitForYellowStep = new StepKey(phase, NAME, WaitForIndexColorStep.NAME);
 
         WaitForIndexingCompleteStep step1 = new WaitForIndexingCompleteStep(indexingComplete, waitForFollowShardTasks);
         WaitForFollowShardTasksStep step2 = new WaitForFollowShardTasksStep(waitForFollowShardTasks, pauseFollowerIndex, client);
         PauseFollowerIndexStep step3 = new PauseFollowerIndexStep(pauseFollowerIndex, closeFollowerIndex, client);
         CloseFollowerIndexStep step4 = new CloseFollowerIndexStep(closeFollowerIndex, unfollowFollowerIndex, client);
         UnfollowFollowerIndexStep step5 = new UnfollowFollowerIndexStep(unfollowFollowerIndex, openFollowerIndex, client);
-        OpenFollowerIndexStep step6 = new OpenFollowerIndexStep(openFollowerIndex, waitForYellowStep, client);
+        OpenIndexStep step6 = new OpenIndexStep(openFollowerIndex, waitForYellowStep, client);
         WaitForIndexColorStep step7 = new WaitForIndexColorStep(waitForYellowStep, nextStepKey, ClusterHealthStatus.YELLOW);
         return Arrays.asList(step1, step2, step3, step4, step5, step6, step7);
     }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ilm/UnfollowAction.java

@@ -13,6 +13,7 @@
 import java.io.IOException;
 import java.util.List;
 
+import static org.elasticsearch.xpack.core.ilm.UnfollowAction.OPEN_FOLLOWER_INDEX_STEP_NAME;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.notNullValue;
@@ -48,7 +49,7 @@ public void testToSteps() {
         StepKey expectedThirdStepKey = new StepKey(phase, UnfollowAction.NAME, PauseFollowerIndexStep.NAME);
         StepKey expectedFourthStepKey = new StepKey(phase, UnfollowAction.NAME, CloseFollowerIndexStep.NAME);
         StepKey expectedFifthStepKey = new StepKey(phase, UnfollowAction.NAME, UnfollowFollowerIndexStep.NAME);
-        StepKey expectedSixthStepKey = new StepKey(phase, UnfollowAction.NAME, OpenFollowerIndexStep.NAME);
+        StepKey expectedSixthStepKey = new StepKey(phase, UnfollowAction.NAME, OPEN_FOLLOWER_INDEX_STEP_NAME);
         StepKey expectedSeventhStepKey = new StepKey(phase, UnfollowAction.NAME, WaitForIndexColorStep.NAME);
 
         WaitForIndexingCompleteStep firstStep = (WaitForIndexingCompleteStep) steps.get(0);
@@ -71,7 +72,7 @@ public void testToSteps() {
         assertThat(fifthStep.getKey(), equalTo(expectedFifthStepKey));
         assertThat(fifthStep.getNextStepKey(), equalTo(expectedSixthStepKey));
 
-        OpenFollowerIndexStep sixthStep = (OpenFollowerIndexStep) steps.get(5);
+        OpenIndexStep sixthStep = (OpenIndexStep) steps.get(5);
         assertThat(sixthStep.getKey(), equalTo(expectedSixthStepKey));
         assertThat(sixthStep.getNextStepKey(), equalTo(expectedSeventhStepKey));