Support for fields for network and network_path

[TomonoriSoejima]

It looks like network and network_path only accepts a hardcoded value while you can specify fields in address.

I think it would benefit users who want to dynamically maintain them.
Currently, you have to reload the config each time you need to change them and it is an extra cost for those managing the system.

[magnusbaeck]

As I read the code the network option supports field references (see cidr.rb:159). What leads you to the conclusion this it doesn't work?

However, network_path doesn't support field references and I'm not sure it should either.

[TomonoriSoejima]

I have not tested it myself, but with a config below produced the warning message appears that that the field whitelist did not get expanded.

cidr { 
add_tag => [ "whitelist" ] 
address => [ "%{source.ip}" ] 
network => [ "%{whitelist}" ] 
} 

[2019-09-10T17:37:00,236][WARN ][logstash.filters.cidr ] Invalid IP network, skipping {:network=>"%{whitelist}", :event=>#<LogStash::Event:0xf7d72a7>} 

[magnusbaeck]

And what does the input event look like?