IllegalArgumentException: Invalid service principal error is shown when Kafka source/sink is added

[ijokarumawak]

Issue description

When Kafka source or sink component is added, and double-clicked, following Error message is shown in SAM UI, and the stack-trace is logged. The error message and log can be more helpful for user to address the situation.

Caused by: java.lang.IllegalArgumentException: Invalid service principal [] for host [hdf0]. If user principal use com.hortonworks.streamline.streams.cluster.service.metadata.json.UserPrincipal
        at com.hortonworks.streamline.streams.cluster.service.metadata.json.ServicePrincipal.forHost(ServicePrincipal.java:34)
        at com.hortonworks.streamline.streams.cluster.service.metadata.json.Principals.lambda$null$4(Principals.java:72)
        at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
        at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374)
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
        at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
        at com.hortonworks.streamline.streams.cluster.service.metadata.json.Principals.lambda$fromAmbariConfig$5(Principals.java:73)
        at java.util.stream.Collectors.lambda$toMap$58(Collectors.java:1321)
        at java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
        at java.util.stream.ReferencePipeline$11$1.accept(ReferencePipeline.java:373)
        at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
        at java.util.Iterator.forEachRemaining(Iterator.java:116)
        at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
        at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
        at com.hortonworks.streamline.streams.cluster.service.metadata.json.Principals.fromAmbariConfig(Principals.java:59)
        at com.hortonworks.streamline.streams.cluster.service.metadata.json.Principals.fromAmbariConfig(Principals.java:40)
        at com.hortonworks.streamline.streams.cluster.service.metadata.KafkaMetadataService.getPrincipals(KafkaMetadataService.java:164)
        at com.hortonworks.streamline.streams.cluster.service.metadata.KafkaMetadataService.getSecurity(KafkaMetadataService.java:174)
        at com.hortonworks.streamline.streams.cluster.bundle.AbstractKafkaBundleHintProvider.getSecurity(AbstractKafkaBundleHintProvider.java:36)
        ... 63 common frames omitted

Steps to reproduce

• Create a SAM Service Pool when Kafka is not Kerberised
• Kerberize Kafka, at this point, SAM holds the Kafka service configuration without authentication
• Add Kafka source/sink at SAM, since Kafka service definition is not updated, the 'SECURITY' tab is not shown. The required parameters such as principal can not be specified from UI.
• SAM server checks Principal and shows the above error.

Steps to recover

• Go to Service Pool and Refresh the pool
• Then the 'SECURITY' configuration tab appears for Kafka source/sink to specify required parameters

Proposal

It seems there is a gap in between SAM UI and Server. Server knows Kafka needs security configurations, but UI does not. UI should show the 'SECURITY' tab, or Server should throw more understandable error message in this situation.