I think it might be better to be configurable entirely via flags rather than having to mess with json, there's not many possible options.

IMHO this is bad idea show login/password in process list.
But if you think this is needed - I will.

Hm, I'd have to agree for the credentials. Those should usually be in a config file or passed via an environment variable. @bjk-soundcloud @matthiasr any opinion on this?

Yeah, password would be a problem then.

Can we make the JSON structure simpler? I think config can be removed

Using env variables and then simply os.Getenv(...) could even be nicer. It doesn't require putting another file in the filesystem, finding it, etc. Your run script can simply set an env variable, no matter where the contents of that come from.

I agree, config is extraneous.

I think the configuration file is fine for now. It won't be a big deal to add other ways later if desired.

I will drop config file and parse env vars

+1 to ENV that contains the DSN0

For repos within the prometheus org we'd like to be consistent with NOTICE, AUTHORS.md, etc. files. Could you make this:

Exporter for MySQL daemon.
Copyright 2015 The Prometheus Authors

The best place for initial authorship attribution would be in the AUTHORS.md file, like in this: https://github.com/prometheus/node_exporter/blob/master/AUTHORS.md

done

I'd also log the error message:

log.Println("error running status query on database:", err)

ok