Add diagnostic channels

API.md

@@ -5030,3 +5030,68 @@ const plugin = {
     }
 };
 ```
+
+## Diagnostic Channels
+
+Diagnostic Channels allows Hapi to report events to other modules. This is useful for APM vendors to collect data from Hapi for diagnostics purposes.
+
+See [the official documentation](https://nodejs.org/docs/latest/api/diagnostics_channel.html) for more information.
+
+### `hapi.onServer`
+
+This event is sent when a new server is created. The [`server`](#server) object is passed as the message.
+
+```js
+const DC = require('diagnostics_channel');
+const channel = DC.channel('hapi.onServer');
+
+channel.subscribe((server) => {
+    // Do something with the server
+    console.log(server.version);
+});
+```
+
+### `hapi.onRoute`
+
+This event is sent when a new route is added to the server. The [`route`](#request.route) object is passed as the message. 
+Similar to `server.events.on('route', (route) => {})`.
+
+```js
+const DC = require('diagnostics_channel');
+const channel = DC.channel('hapi.onRoute');
+
+channel.subscribe((route) => {
+    // Do something with the route
+    console.log(route.path);
+});
+```
+
+### `hapi.onRequest`
+
+This event is sent when a request is generated by the framework. The [`request`](#request) object is passed as the message.
+Similar to `server.events.on('request', (request) => {})`.
+
+```js
+const DC = require('diagnostics_channel');
+const channel = DC.channel('hapi.onRequest');
+
+channel.subscribe((request) => {
+    // Do something with the request
+    console.log(request.info.id);
+});
+```
+
+### `hapi.onResponse`
+
+This event is sent after the response is sent back to the client. The [`response`](#request.response) object is passed as the message.
+Similar to `server.events.on('response', ({ response }) => {})`.
+
+```js
+const DC = require('diagnostics_channel');
+const channel = DC.channel('hapi.onResponse');
+
+channel.subscribe((response) => {
+    // Do something with the response
+    console.log(response.statusCode);
+});
+```

lib/channels.js

@@ -0,0 +1,10 @@
+'use strict';
+
+const DC = require('diagnostics_channel');
+
+module.exports = {
+    onServerChannel: DC.channel('hapi.onServer'),
+    onRouteChannel: DC.channel('hapi.onRoute'),
+    onResponseChannel: DC.channel('hapi.onResponse'),
+    onRequestChannel: DC.channel('hapi.onRequest')
+};

lib/core.js

@@ -17,6 +17,7 @@ const Podium = require('@hapi/podium');
 const Statehood = require('@hapi/statehood');
 
 const Auth = require('./auth');
+const Channels = require('./channels');
 const Compression = require('./compression');
 const Config = require('./config');
 const Cors = require('./cors');
@@ -510,6 +511,8 @@ exports = module.exports = internals.Core = class {
 
             const request = Request.generate(this.root, req, res, options);
 
+            Channels.onRequestChannel.publish(request);
+
             // Track socket request processing state
 
             if (this.settings.operations.cleanStop &&

lib/request.js

@@ -8,6 +8,7 @@ const Bounce = require('@hapi/bounce');
 const Hoek = require('@hapi/hoek');
 const Podium = require('@hapi/podium');
 
+const Channels = require('./channels');
 const Cors = require('./cors');
 const Toolkit = require('./toolkit');
 const Transmit = require('./transmit');
@@ -510,6 +511,8 @@ exports = module.exports = internals.Request = class {
 
         this._core.events.emit('response', this);
 
+        Channels.onResponseChannel.publish(this.response);
+
         if (this._route._extensions.onPostResponse.nodes) {
             this._invoke(this._route._extensions.onPostResponse, { ignoreResponse: true });
         }

lib/server.js

@@ -4,6 +4,7 @@ const Hoek = require('@hapi/hoek');
 const Shot = require('@hapi/shot');
 const Teamwork = require('@hapi/teamwork');
 
+const Channels = require('./channels');
 const Config = require('./config');
 const Core = require('./core');
 const Cors = require('./cors');
@@ -83,6 +84,8 @@ internals.Server = class {
         }
 
         core.registerServer(this);
+
+        Channels.onServerChannel.publish(this);
     }
 
     _clone(name) {
@@ -532,6 +535,9 @@ internals.Server = class {
         }
 
         this.events.emit('route', route.public);
+
+        Channels.onRouteChannel.publish(route.public);
+
         Cors.options(route.public, server);
     }
 

test/channels.js

@@ -0,0 +1,121 @@
+'use strict';
+
+const DC = require('diagnostics_channel');
+
+const Code = require('@hapi/code');
+const Lab = require('@hapi/lab');
+
+const Hapi = require('..');
+
+const { describe, it } = exports.lab = Lab.script();
+const expect = Code.expect;
+
+describe('DiagnosticChannel', () => {
+
+    describe('onServerChannel', () => {
+
+        const channel = DC.channel('hapi.onServer');
+
+        it('server should be exposed on creation through the channel hapi.onServer', async () => {
+
+            let exposedServer;
+            let server;
+
+            await new Promise((resolve) => {
+
+                channel.subscribe((srv) => {
+
+                    exposedServer = srv;
+                    resolve();
+                });
+
+                server = Hapi.server();
+            });
+
+            expect(exposedServer).to.equal(server);
+        });
+    });
+
+    describe('onRouteChannel', () => {
+
+        const channel = DC.channel('hapi.onRoute');
+
+        it('route should be exposed on creation through the channel hapi.onRoute', async () => {
+
+            const server = Hapi.server();
+            let route;
+
+            await new Promise((resolve) => {
+
+                channel.subscribe((rte) => {
+
+                    route = rte;
+                    resolve();
+                });
+
+                server.route({
+                    method: 'GET',
+                    path: '/',
+                    options: { app: { x: 'o' } },
+                    handler: () => 'ok'
+                });
+            });
+
+            expect(route).to.be.an.object();
+            expect(route.settings.app.x).to.equal('o');
+        });
+    });
+
+    describe('onResponseChannel', () => {
+
+        const channel = DC.channel('hapi.onResponse');
+
+        it('response should be exposed on creation through the channel hapi.onResponse', async () => {
+
+            const server = Hapi.server();
+            let responseExposed;
+
+            server.route({ method: 'GET', path: '/', handler: () => 'ok' });
+
+            const eventPromise = new Promise((resolve) => {
+
+                channel.subscribe((res) => {
+
+                    responseExposed = res;
+                    resolve();
+                });
+            });
+
+            const response = await server.inject('/');
+            await eventPromise;
+
+            expect(response.request.response).to.equal(responseExposed);
+        });
+    });
+
+    describe('onRequestChannel', () => {
+
+        const channel = DC.channel('hapi.onRequest');
+
+        it('request should be exposed on creation through the channel hapi.onRequest', async () => {
+
+            const server = Hapi.server();
+            let requestExposed;
+
+            server.route({ method: 'GET', path: '/', handler: () => 'ok' });
+
+            const eventPromise = new Promise((resolve) => {
+
+                channel.subscribe((req) => {
+
+                    requestExposed = req;
+                    resolve();
+                });
+            });
+
+            const response = await server.inject('/');
+            await eventPromise;
+            expect(response.request).to.equal(requestExposed);
+        });
+    });
+});