CentOS - Oct 2017 - Docker log level

Hi, folks,

   Just installed and fired up docker for a user, and the default log
level is stupidly noisy. Now, doing some googling, I see that I can set
the log level on the command line. What I'd *like* to do is set the log
level in the appropriate config file, which I gather is
/etc/docker/daemon.json. So far, though, I can't find anything that
suggests I can do that.

   Anyone here know if I can, and if so, what the correct syntax is?

   Thanks in advance.