Put a master server in read_only to execute maintenance while accepting reads

Folks,

I'm working with an environment in which the customer has two Maxscale on version 2.0.X and two sets of master/slave geo-located. we're planning a maintenance and the customer asked me if I can put the master servers in read_only mode on Maxscale in order to permit queries to be yet redirected to master, but just reads, writes should be routed to /dev/nul (e.g.) at this point.

I was thinking of something like:

$ maxadmin "remove | set server <master_servername> read_only"

This is something that a customer asked me and I think it's a good thing as we can control this behavior on the Maxscale while don't touching the configs on the server level.