[NIFI-6055] Improve error handling during auto-loading of NARs

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.9.0
• Fix Version/s: 1.10.0, 1.9.1
• Assignee: Bryan Bende
• Reporter: Bryan Bende
• Created: 19/Feb/19 16:48
• Updated: 12/Mar/19 19:40
• Resolved: 22/Feb/19 17:24

Description

If you copy in several NARs where one of them has a framework level extension like an authorizers, repository, or state manager, it will produce an exception like the following:

2019-02-19 10:37:20,397 ERROR [NAR Auto-Loader] org.apache.nifi.nar.NarAutoLoaderTask Error loading NARs due to: Attempt was made to load org.apache.nifi.provenance.PersistentProvenanceRepository from org.apache.nifi:nifi-provenance-repository-nar:1.9.0-SNAPSHOT but that class name is already loaded/registered from org.apache.nifi:nifi-provenance-repository-nar:1.9.0 and multiple versions are not supported for this type
java.lang.IllegalStateException: Attempt was made to load org.apache.nifi.provenance.PersistentProvenanceRepository from org.apache.nifi:nifi-provenance-repository-nar:1.9.0-SNAPSHOT but that class name is already loaded/registered from org.apache.nifi:nifi-provenance-repository-nar:1.9.0 and multiple versions are not supported for this type
        at org.apache.nifi.nar.StandardExtensionDiscoveringManager.registerServiceClass(StandardExtensionDiscoveringManager.java:289)
        at org.apache.nifi.nar.StandardExtensionDiscoveringManager.loadExtensions(StandardExtensionDiscoveringManager.java:181)
        at org.apache.nifi.nar.StandardExtensionDiscoveringManager.discoverExtensions(StandardExtensionDiscoveringManager.java:127)
        at org.apache.nifi.nar.StandardNarLoader.load(StandardNarLoader.java:110)
        at org.apache.nifi.nar.NarAutoLoaderTask.run(NarAutoLoaderTask.java:128)
        at java.lang.Thread.run(Thread.java:748)

The exception itself is not an issue because it is correct that we don't support multiple versions of these types of extensions.

The issue is that during the auto-loading process we call discoverExtensions on a set of bundles:

extensionManager.discoverExtensions(loadedBundles);

If the above exception happens during this call, it will bounce out and not discover any other extensions that may still be available for loading.

 

Issue Links

• links to: GitHub Pull Request #3322