[jira] [Resolved] (NIFI-4176) IPLookupService should avoid using FILE_EXISTS_VALIDATOR

["Mark Payne (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/NIFI-4176?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mark Payne resolved NIFI-4176.
------------------------------
    Resolution: Not A Problem

This is no longer a problem because when the Controller Service is enabled, if it is invalid, it will continue trying to enable periodically until the service becomes valid. At that point, it will automatically enable itself (if not yet disabled).

> IPLookupService should avoid using FILE_EXISTS_VALIDATOR
> --------------------------------------------------------
>
>                 Key: NIFI-4176
>                 URL: https://issues.apache.org/jira/browse/NIFI-4176
>             Project: Apache NiFi
>          Issue Type: Bug
>          Components: Extensions
>            Reporter: Mark Payne
>            Priority: Major
>
> Currently, the IPLookupService uses a FILE_EXISTS_VALIDATOR in order to ensure that the given database file exists. Quite often, though, a flow is developed in such a way that the file is dynamically fetched via GetHTTP, InvokeHTTP, etc. and then written out so that IPLookupService is able to automatically reload the data.
> If a new flow is imported via template, for example, or copied from another NiFi instance, the file may not yet exist. As a result, the Controller Service is invalid and upon startup the service is not enabled. This then causes referencing processors not to start. This can be particularly problematic if running in a cluster where some nodes have the file and start the processor while other nodes do not.
> To avoid this, the IPLookupService (and Controller Services, in general) should not use the FILE_EXISTS_VALIDATOR but instead just fail in the @OnScheduled method. This way, the service will continually attempt to start and once the file does exist, everything will begin flowing as expected.



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