[Transform] add rolling upgrade tests for upgrade endpoint (#79721) (#80012)

add rolling upgrade tests for upgrade endpoint

Co-authored-by: Elastic Machine <[email protected]>

Author: Hendrik Muhs

x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/TransformSurvivesUpgradeIT.java

@@ -9,6 +9,7 @@
 import org.apache.http.HttpHost;
 import org.apache.http.entity.ContentType;
 import org.apache.http.entity.StringEntity;
+import org.elasticsearch.Version;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
 import org.elasticsearch.client.RestClient;
@@ -50,6 +51,7 @@
 import static org.elasticsearch.xpack.test.rest.XPackRestTestConstants.TRANSFORM_INTERNAL_INDEX_PREFIX;
 import static org.elasticsearch.xpack.test.rest.XPackRestTestConstants.TRANSFORM_INTERNAL_INDEX_PREFIX_DEPRECATED;
 import static org.elasticsearch.xpack.test.rest.XPackRestTestConstants.TRANSFORM_TASK_NAME;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
@@ -108,10 +110,12 @@ public void testTransformRollingUpgrade() throws Exception {
                     lastCheckpoint = 2;
                 }
                 verifyContinuousTransformHandlesData(lastCheckpoint);
+                verifyUpgradeFailsIfMixedCluster();
                 break;
             case UPGRADED:
                 client().performRequest(waitForYellow);
                 verifyContinuousTransformHandlesData(3);
+                verifyUpgrade();
                 cleanUpTransforms();
                 break;
             default:
@@ -216,6 +220,23 @@ private void verifyContinuousTransformHandlesData(long expectedLastCheckpoint) t
         });
     }
 
+    private void verifyUpgradeFailsIfMixedCluster() {
+        // upgrade tests by design are also executed with the same version, this check must be skipped in this case, see gh#39102.
+        if (UPGRADE_FROM_VERSION.equals(Version.CURRENT)) {
+            return;
+        }
+        final Request upgradeTransformRequest = new Request("POST", getTransformEndpoint() + "_upgrade");
+
+        Exception ex = expectThrows(Exception.class, () -> client().performRequest(upgradeTransformRequest));
+        assertThat(ex.getMessage(), containsString("All nodes must be the same version"));
+    }
+
+    private void verifyUpgrade() throws IOException {
+        final Request upgradeTransformRequest = new Request("POST", getTransformEndpoint() + "_upgrade");
+        Response response = client().performRequest(upgradeTransformRequest);
+        assertEquals(200, response.getStatusLine().getStatusCode());
+    }
+
     private void awaitWrittenIndexerState(String id, Consumer<Map<?, ?>> responseAssertion) throws Exception {
         Request getStatsDocsRequest = new Request(
             "GET",

x-pack/qa/rolling-upgrade/src/test/resources/rest-api-spec/test/upgraded_cluster/80_transform_jobs_crud.yml

@@ -6,7 +6,7 @@ setup:
         # wait for long enough that we give delayed unassigned shards to stop being delayed
         timeout: 70s
 ---
-"Get start, stop, and delete old cluster batch transform":
+"Get start, stop, upgrade and delete old cluster batch transform":
   # Simple and complex OLD transforms
   - do:
       transform.get_transform:
@@ -75,6 +75,13 @@ setup:
   - match: { count: 1 }
   - match: { transforms.0.id: "old-complex-transform" }
   - match: { transforms.0.state: "stopped" }
+
+  # upgrade transform
+  # note: upgrade is not always required, therefore the output can not be tested
+  - do:
+      transform.upgrade_transforms:
+        dry_run: false
+
   # Delete old transform
   - do:
       transform.delete_transform: