Add X-Response-Time header at each request for Fastify. The unit used is milliseconds.

Add Server-Timing header, that could be used to pass timing server to client (useful to debug). You could find some documentation at W3C Server-Timing documentation.

You need to use Fastify version 0.31 or newer, the hook used (onSend) was added in this version

If you need older Fastify version, use version 1.0.1 of this plugin

npm install --save fastify-response-time

Add it to you project with register and you are done!

// Register the plugin
fastify.register(require("fastify-response-time"));

// Define a new route in hapijs notation
fastify.route({
  method: "GET",
  url: "/header-hapi",
  handler: (request, reply) => {
    reply.send();
  }
});

// Define a new route in express notation
fastify.get("/header-express", (request, reply) => {
  reply.send();
});

// Add server timing information
fastify.get("/header-express", (request, reply) => {
  reply.setServerTiming("cache", 5.3, "Cache read");
  reply.send();
});

Both examples responds with:

< HTTP/1.1 200 OK
< Content-Type: application/json
< Content-Length: 17
< X-Response-Time: 0.08
< Date: Fri, 15 Sep 2017 21:14:33 GMT
< Connection: keep-alive
<

This plugin allow you to specify options:

• header can be used to change default header name to something else (X-Response-Time by default)
• digits to specify the number of digits in the response (2 by default, so 1.03)

reply.setServerTiming( name , duration , description ) => boolean

With:

• name: [mandatory] the name of the measure, and must be unique. Any already existing value will not be replaced
• duration: [optional] the duration, that must be an integer or float. If not needed, pass 0 or null
• description: [optional] the description is needed. It must be a string
• return true if the measure is added the the list that will be send with the request, false is the name already exists

The response will be:

< HTTP/1.1 200 OK
< Content-Type: application/json
< Content-Length: 17
< X-Response-Time: 0.08
< Server-Timing: cache;dur=5.3;desc="Cache read"
< Date: Fri, 15 Sep 2017 21:14:33 GMT
< Connection: keep-alive
<