Provide dry-run mode

[hrzbrg]

Is your feature request related to a problem? Please describe.
I would like to compare aws-node-termination-handler with our current approach of listening to the CloudWatch event in terms of timing.

Describe the solution you would like
The application should take a --dry-run flag that will disable the actual execution of the draining but still print the log messages. During startup it should log out that the application is running in dry-run mode.

Thanks
hrzbrg

[mattrandallbecker]

Great suggestion, I think the ability to run the daemonset in effectively debug mode makes sense.

Also for some history we did explore listening to the CloudWatch event as a possible avenue for the handler but it required additional infrastructure setup and some minor additional cost to your AWS account. We are exploring adding some additional flags and we'll try to address this at the same time.