NIFI-5792: Remember created versioned flow information

- Before this fix, NiFi loses information about created versioned flow in case of subsequent snapshot creation failure, and NiFi API returned an error response
- This commit makes:
  - The created versioned Flow information is stored even if subsequent snapshot creation fails
  - NiFi API to return a successful 200 response in that case, but return versioned flow status as SYNC_FAILURE with an explanation. NiFi UI shows a popup error dialog with the explanation.
  - Versioned flow status will be LOCALLY_MODIFIED if the latest version is 0.

This closes #3134.

Signed-off-by: Mark Payne <markap14@hotmail.com>

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-core/src/main/java/org/apache/nifi/groups/StandardProcessGroup.java

@@ -3057,6 +3057,10 @@ public final class StandardProcessGroup implements ProcessGroup {
             }
 
             private boolean isModified() {
+                if (versionControlInformation.getVersion() == 0) {
+                    return true;
+                }
+
                 Set<FlowDifference> differences = versionControlFields.getFlowDifferences();
                 if (differences == null) {
                     differences = getModifications();
@@ -3110,7 +3114,7 @@ public final class StandardProcessGroup implements ProcessGroup {
         final VersionedFlowState flowState = versionControlInformation.getStatus().getState();
         versionControlFields.setStale(flowState == VersionedFlowState.STALE || flowState == VersionedFlowState.LOCALLY_MODIFIED_AND_STALE);
         versionControlFields.setLocallyModified(flowState == VersionedFlowState.LOCALLY_MODIFIED || flowState == VersionedFlowState.LOCALLY_MODIFIED_AND_STALE);
-        versionControlFields.setSyncFailureExplanation(null);
+        versionControlFields.setSyncFailureExplanation(flowState == VersionedFlowState.SYNC_FAILURE ? versionControlInformation.getStatus().getStateExplanation() : null);
 
         writeLock.lock();
         try {
@@ -3268,7 +3272,7 @@ public final class StandardProcessGroup implements ProcessGroup {
         }
 
         final VersionedProcessGroup snapshot = vci.getFlowSnapshot();
-        if (snapshot == null) {
+        if (snapshot == null && vci.getVersion() > 0) {
             // We have not yet obtained the snapshot from the Flow Registry, so we need to request the snapshot of our local version of the flow from the Flow Registry.
             // This allows us to know whether or not the flow has been modified since it was last synced with the Flow Registry.
             try {
@@ -3301,8 +3305,13 @@ public final class StandardProcessGroup implements ProcessGroup {
             vci.setRegistryName(flowRegistry.getName());
 
             if (latestVersion == vci.getVersion()) {
-                LOG.debug("{} is currently at the most recent version ({}) of the flow that is under Version Control", this, latestVersion);
                 versionControlFields.setStale(false);
+                if (latestVersion == 0) {
+                    LOG.debug("{} does not have any version in the Registry", this, latestVersion);
+                    versionControlFields.setLocallyModified(true);
+                } else {
+                    LOG.debug("{} is currently at the most recent version ({}) of the flow that is under Version Control", this, latestVersion);
+                }
             } else {
                 LOG.info("{} is not the most recent version of the flow that is under Version Control; current version is {}; most recent version is {}",
                         this, vci.getVersion(), latestVersion);

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-api/src/main/java/org/apache/nifi/web/StandardNiFiServiceFacade.java

@@ -3778,24 +3778,46 @@ public class StandardNiFiServiceFacade implements NiFiServiceFacade {
         final String registryId = requestEntity.getVersionedFlow().getRegistryId();
         final VersionedFlowSnapshot registeredSnapshot;
         final VersionedFlow registeredFlow;
+        final boolean registerNewFlow = versionedFlowDto.getFlowId() == null;
 
-        String action = "create the flow";
         try {
             // first, create the flow in the registry, if necessary
-            if (versionedFlowDto.getFlowId() == null) {
+            if (registerNewFlow) {
                 registeredFlow = registerVersionedFlow(registryId, versionedFlow);
             } else {
                 registeredFlow = getVersionedFlow(registryId, versionedFlowDto.getBucketId(), versionedFlowDto.getFlowId());
             }
-
-            action = "add the local flow to the Flow Registry as the first Snapshot";
-
-            // add first snapshot to the flow in the registry
-            registeredSnapshot = registerVersionedFlowSnapshot(registryId, registeredFlow, versionedProcessGroup, versionedFlowDto.getComments(), expectedVersion);
         } catch (final NiFiRegistryException e) {
             throw new IllegalArgumentException(e.getLocalizedMessage());
         } catch (final IOException ioe) {
-            throw new IllegalStateException("Failed to communicate with Flow Registry when attempting to " + action);
+            throw new IllegalStateException("Failed to communicate with Flow Registry when attempting to create the flow");
+        }
+
+        try {
+            // add a snapshot to the flow in the registry
+            registeredSnapshot = registerVersionedFlowSnapshot(registryId, registeredFlow, versionedProcessGroup, versionedFlowDto.getComments(), expectedVersion);
+        } catch (final NiFiCoreException e) {
+            // If the flow has been created, but failed to add a snapshot,
+            // then we need to capture the created versioned flow information as a partial successful result.
+            if (registerNewFlow) {
+                logger.error("The flow has been created, but failed to add a snapshot. Returning the created flow information.", e);
+                final VersionControlInformationDTO vci = new VersionControlInformationDTO();
+                vci.setBucketId(registeredFlow.getBucketIdentifier());
+                vci.setBucketName(registeredFlow.getBucketName());
+                vci.setFlowId(registeredFlow.getIdentifier());
+                vci.setFlowName(registeredFlow.getName());
+                vci.setFlowDescription(registeredFlow.getDescription());
+                vci.setGroupId(groupId);
+                vci.setRegistryId(registryId);
+                vci.setRegistryName(getFlowRegistryName(registryId));
+                vci.setVersion(0);
+                vci.setState(VersionedFlowState.SYNC_FAILURE.name());
+                vci.setStateExplanation(e.getLocalizedMessage());
+
+                return createVersionControlComponentMappingEntity(groupId, versionedProcessGroup, vci);
+            }
+
+            throw e;
         }
 
         final Bucket bucket = registeredSnapshot.getBucket();
@@ -3814,6 +3836,10 @@ public class StandardNiFiServiceFacade implements NiFiServiceFacade {
         vci.setVersion(registeredSnapshot.getSnapshotMetadata().getVersion());
         vci.setState(VersionedFlowState.UP_TO_DATE.name());
 
+        return createVersionControlComponentMappingEntity(groupId, versionedProcessGroup, vci);
+    }
+
+    private VersionControlComponentMappingEntity createVersionControlComponentMappingEntity(String groupId, InstantiatedVersionedProcessGroup versionedProcessGroup, VersionControlInformationDTO vci) {
         final Map<String, String> mapping = dtoFactory.createVersionControlComponentMappingDto(versionedProcessGroup);
 
         final Revision groupRevision = revisionManager.getRevision(groupId);

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-ui/src/main/webapp/js/nf/canvas/nf-flow-version.js

@@ -421,6 +421,13 @@
             url: '../nifi-api/versions/process-groups/' + encodeURIComponent(processGroupId),
             dataType: 'json',
             contentType: 'application/json'
+        }).done(function (response) {
+            if ('SYNC_FAILURE' === response.versionControlInformation.state) {
+                nfDialog.showOkDialog({
+                    headerText: 'Error',
+                    dialogContent: response.versionControlInformation.stateExplanation
+                });
+            }
         }).fail(nfErrorHandler.handleAjaxError);
     };