Add configuration for logger

[keis]

Makes it possible to configure

• log file (or explicit stderr logging using "-")
• log level

Log level doesn't do much but I think it's a sensible thing to have.

On a related note it would be more idiomatic to use log.Debug and let logrus sort it out rather than using a custom if d.Debug { ... }. It's a more controversial change though and maybe there's some context I'm missing that makes that preferable.

If you think it's a good idea I can add that too

[jurkovic-nikola]

Hello, please modify your code to include proper JSON values, so IDE doesn't dump warnings about fields.

LogLevel log.Level json:"logLevel"``

There is no reason to have LogFile config field, since you placed omit omitempty and never initialized variable in upgrade process, so this will always default to "". Instead of manipulation of logging file, if you don't want logging into a file, define config field for console or file logging.

d.Debug is there for a debug purpose, since when you flip this value, all packet sent towards device and vice versa will be logged, this will scale to 1000 lines of log under 1 minute if you have couple of devices in your system.

And LogLevel do much, if you set this to error, you'll never have any warnings logged or anything bellow the error level.

[keis]

updated!

What I meant regarding the log level is that setting it to info doesn't do much right now as all the debug logging uses the the info level anyway and not, as I would argue would be more appropriate, debug level. For stuff like dumping traffic maybe even trace.

Using those log levels where suitable could make the Debug option kinda redundant.