在Gorilla CustomLoggingHandler中获取JWT数据

I am using a custom logging handler in my Go web server like this:

func main() {
    // ... Set up everything

    router = mux.NewRouter()
    router.Handle("/apilookup",
        raven.Recoverer(
            jwtMiddleware.Handler(
                http.HandlerFunc(
                    doApiLookup)))).Methods("GET")

    loggedRouter := handlers.CustomLoggingHandler(os.Stdout, router, writeLog)

    http.ListenAndServe(listenAddr, loggedRouter)
}

In the writeLog function, I have made my own version of the Gorilla handlers.LoggingHandler, which logs a lot of additional information.

One thing I would like to do is log the user for authenticated requests. Users authenticate to this server using JWT (using the Authorization: Bearer ... header). I am using Auth0's go-jwt-middleware to parse the token and set its value in the Request's context.

I tried to log the user's email address (one of the claims in the JWT) like this, based on the middleware's documentation:

func writeLog(writer io.Writer, params handlers.LogFormatterParams) {

    // ... SNIP

    // If we can't identify the user
    username := "-"

    if userJwt := params.Request.Context().Value("user"); userJwt != nil {
        claims := userJwt.(*jwt.Token).Claims.(*jwtClaims)
        username = claims.Email
    }

    // ... SNIP
}

The problem is that username is always the initial value - and not the expected value from the JWT.

By adding log.Printf("%+v ", params.Request.Context()) above the if, I see that the context doesn't actually contain the parsed JWT data here.

As far as I can tell, the reason this is not working is because the middleware creates a new Request with the updated context, so only middleware further down the chain can see it. Because the logging middleware is above the JWT middleware, it does not have that same context.

I know that I can re-parse the JWT in the logging handler (because I do have access to all the headers), but that seems like a lot of overhead for logging.

Is there a better way to do this that will allow me to have access to this data where I want it?