[PLAT-18685] Enable capacity reservation for single node

Summary:
Previously, there were no sense in using reservation for single node (as during failure we will still have to retry task.
Now, with automatic rollback, it is useful to create reservation.

Test Plan: edit universe add one node - verify reservation was applied.

Reviewers: spothuraju

Reviewed By: spothuraju

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D47219

Author: yorq

managed/src/main/java/com/yugabyte/yw/commissioner/tasks/EditUniverse.java

@@ -84,13 +84,12 @@ public void run() {
     boolean deleteCapacityReservation = false;
     String errorMessage = null;
     try {
-      Consumer<Universe> retryCallback = null;
-      if (Universe.getOrBadRequest(taskParams().getUniverseUUID())
-          .getUniverseDetails()
-          .autoRollbackPerformed) {
-        // Need to write nodes to universe since there was a rollback.
-        retryCallback = univ -> updateUniverseNodesAndSettings(univ, taskParams(), false);
-      }
+      Consumer<Universe> retryCallback =
+          (univ) -> {
+            if (univ.getUniverseDetails().autoRollbackPerformed) {
+              updateUniverseNodesAndSettings(univ, taskParams(), false);
+            }
+          };
       universe =
           lockAndFreezeUniverseForUpdate(
               taskParams().getUniverseUUID(),
@@ -171,7 +170,7 @@ public void run() {
     } catch (Throwable t) {
       errorMessage = t.getMessage();
       log.error("Error executing task {} with error='{}'.", getName(), t.getMessage(), t);
-      clearCapacityReservationOnError(t, Universe.getOrBadRequest(universe.getUniverseUUID()));
+      clearCapacityReservationOnError(t, Universe.getOrBadRequest(taskParams().getUniverseUUID()));
       throw t;
     } finally {
       releaseReservedNodes();

managed/src/main/java/com/yugabyte/yw/commissioner/tasks/UniverseDefinitionTaskBase.java

@@ -4086,8 +4086,7 @@ protected boolean createCapacityReservationsIfNeeded(
       Set<NodeDetails> nodeDetailsSet,
       CapacityReservationUtil.OperationType operationType,
       Predicate<NodeDetails> nodeFilter) {
-    // There is no sense in using capacity reservation for a single node.
-    if (nodeDetailsSet.size() < 2) {
+    if (nodeDetailsSet.isEmpty()) {
       return false;
     }
     Universe universe = getUniverse();

managed/src/test/java/com/yugabyte/yw/commissioner/tasks/EditUniverseTest.java

@@ -614,7 +614,7 @@ public void testExpandRollback() {
     universe = Universe.getOrBadRequest(universe.getUniverseUUID());
     assertEquals(nodes, universe.getUniverseDetails().nodeDetailsSet.size());
     assertTrue(universe.getUniverseDetails().autoRollbackPerformed);
-    assertNull(universe.getUniverseDetails().updatingTaskUUID);
+    assertNotNull(universe.getUniverseDetails().updatingTaskUUID);
     assertNull(universe.getUniverseDetails().placementModificationTaskUuid);
   }
 
@@ -646,7 +646,7 @@ public void testFullMoveRollback() {
     universe = Universe.getOrBadRequest(universe.getUniverseUUID());
     assertEquals(nodes, universe.getUniverseDetails().nodeDetailsSet.size());
     assertTrue(universe.getUniverseDetails().autoRollbackPerformed);
-    assertNull(universe.getUniverseDetails().updatingTaskUUID);
+    assertNotNull(universe.getUniverseDetails().updatingTaskUUID);
     assertNull(universe.getUniverseDetails().placementModificationTaskUuid);
   }