Change concrete *log.Logger to mesh.Logger interface

[peterbourgon]

Proposed interface

type Logger interface {
    Logf(format string, args ...interface{})
}

[bboreham]

Compare https://github.com/Sirupsen/logrus/blob/master/logrus.go#L97

(not claiming I can see an easy middle ground)

See also weaveworks/weave@c38dcb1

[peterbourgon]

Yeah, there's a lot to consider. I'm definitely against an interface with more than 1 method, see this presentation from a Go kit collaborator for a good recap of my journey with logging. And sorry to make you use that logLogger.