Custom middleware after nextjs RequestHandler

Feature request

Related to https://github.com/zeit/next.js/issues/6290 We need to run some logic after every route is handled.

Is your feature request related to a problem? Please describe.

We have a Prometheus client where we report performance metrics. “handleRequest” does not call next and therefore our code is never invoked.

Custom Server Example

  // Runs before each requests
  server.use((req, res, next) => {
    res.locals.startEpoch = Date.now();
    next();
  });

  server.get("/", (req, res) => {
    return handleRequest(req, res, "/", req.query);
  });

  server.get("*", (req, res) => {
    return handleRequest(req, res);
  });

  // Runs after each requests - **THIS NEVER GETS INVOKED**
  server.use((req, res, next) => {
    const responseTimeInMs = Date.now() - res.locals.startEpoch;
    httpRequestDurationMicroseconds
      .labels(req.method, req.route.path, res.statusCode)
      .observe(responseTimeInMs);

    next();
  });

Describe the solution you’d like

handleRequest should call next This would solve https://github.com/zeit/next.js/issues/7499 as well allowing people to add middlewares

Describe alternatives you’ve considered

I’ve not found a workaround

[timneutkens]

Next.js does not provide a middleware, it ends the request when you call handle. So like @janpot is saying you’ll probably want to add on finish or similar.

[timneutkens]

There already was an open RFC before this issue was posted: https://github.com/zeit/next.js/issues/7208