This looks good to me.

@njharter can this be merged?

We don't want to be doing bookkeeping this way, in any of our servers:

• Bookkeeping should not be present in application layer code. This makes it hard to refactor later.
• Bookkeeping is a cross-cutting concern, and should be done with an Alice-style decorator. There is already code to facilitate this in the logging and xcontext packages.
• Logging decorations should transfer to every log message in an HTTP code path, not just the bookkeeping message.

There are (3) basic steps to a better solution. The first (2) need only be done once, for all servers.

(1) Use xcontext.Populate to create an Alice-style decorator:

c := xcontext.Populate(0, logginghttp.SetLogger(
        logginghttp.Header("X-Webpa-Device-Name", "deviceName"),
        // any other go-kit request functions that you want go here, e.g. to pull data from a SAT
    ),
)

(2) Create a bookkeeping decorator, preferably in one place such as the logginghttp package:

b := func(next http.Handler) http.Handler {
    return http.HandlerFunc(func(response http.ResponseWriter, request *http.Request) {
        logging.GetLogger(request.Context()).Log(level.Key(), level.InfoValue(), logging.MessageKey(), "Bookkeeping")
    })
}

(3) Use both of the above decorators for any handlers in application code:

r := mux.NewRouter()

// decorate one handler
r.Handle("/foobar", alice.New(c, b).Then(myHandler))

// decorate the whole thing
alice.New(c, b).Then(r)