[NIFI-6286] Make listHDFS work as INPUT_ALLOWED processor -> create new ScanHDFS processor

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.9.2
• Component/s: Core Framework
• Labels: features
• Assignee: Jasper Knulst
• Reporter: Jasper Knulst
• Created: 10/May/19 10:02
• Updated: 31/May/19 11:25

Description

Currently the listHDFS processor has a prop 'Directory' (to start the listing from, recursively or not) which only allows 1 static value.

There are many use cases where you would want to crawl many roots in sequence. There are 2 ways to do it.

1. Allow the 'Directory' prop to have multiple comma separated values
2. Refactor listHDFS as an INPUT_ALLOWED processor and make the 'Directory' prop take EL to get directory roots from upstream

Option 1. has serious restrictions since it dictates that other config (like recursive, filter type and regex) would still be static and may get very complex, non-intuitive and require frequent re-configuration.

Option 2. is the way to go.

Some things to consider:

-The way listHDFS behaves now should be preserved

-It makes sense to dynamically set 'Directory', 'Recursiveness', 'Regex' and 'Filter type' in tandem      to be able to detail the way each root directory is crawled

-Switching 'Directory' also requires that not just 1 state is stored but states for each directory that ever passed

Issue Links

• relates to: NIFI-6275 ListHDFS with Full Path filter mode regex does not work as intended
• links to: GitHub Pull Request #3496
• links to: GitHub Pull Request #3498