New option to filter the plugins to run at startup

[zepouet]

Hello,

I just add a new option to filter plugins to enable at startup.

In the future, we will have a lot of plugins into all.go and into config.toml.
A solution would be to have many differents config files.
Another one could be to use this option to filter the plugins.

go run cmd/telegraf/telegraf.go --config telegraf.toml -filter mysql:redis

I hope it is a good idea. For me it is nice to understand the code behind and now how to write plugin.
Best regards,

Nicolas

[evanphx]

What's the reason for being able to filter the plugins like this?

[zepouet]

Hello,

Maybe I am wrong but If I want to use the same config file and activate only one plugin, the filter option could be nice. Else I must duplicate config file and delete other plugin to disable them.
The config file share common configuration so it is nice to avoid to duplicate it.

Thanks for reading this PR.

Best regards,
Nicolas

[sparrc]

@zepouet Please update the README with an example under Quickstart -> How to use it and resolve the branch conflicts so I can merge it, thanks!

[zepouet]

Hello,

I close this PR because I created a new one with more comment and file for running unit test. : #106

Sorry I deleted my local branch by mistake (my fork) so I could not merge as you ask me :(
Thanks a lot.

Best regards