Conditional connectionless mode. Closes #3350

API.md

@@ -1,4 +1,4 @@
-# 15.0.x API Reference
+# 15.1.x API Reference
 
 - [Server](#server)
     - [`new Server([options])`](#new-serveroptions)
@@ -2212,7 +2212,10 @@ The plugin function must include an `attributes` function property with the foll
   setting dependencies via [`server.dependency()`](#serverdependencydependencies-after).
 - `connections` - if `false`, does not allow the plugin to call server APIs that modify the
   connections such as adding a route or configuring state. This flag allows the plugin to be
-  registered before connections are added and to pass dependency requirements. Defaults to `true`.
+  registered before connections are added and to pass dependency requirements. When set to
+  `'conditional'`, the mode is based on the presence of selected connections (if the server
+  has connections, it is the same as `true`, but if no connections are available, it is the
+  same as `false`). Defaults to `true`.
 - `once` - if `true`, will only register the plugin once per connection (or once per server for a
   connectionless plugin). If set, overrides the `once` option passed to `server.register()`.
   Defaults to `undefined` (registration will be based on the `server.register()` option `once`).

README.md

@@ -10,7 +10,7 @@ Lead Maintainer: [Eran Hammer](https://github.com/hueniverse)
 authentication, and other essential facilities for building web and services applications. **hapi** enables
 developers to focus on writing reusable application logic in a highly modular and prescriptive approach. 
 
-Development version: **15.0.x** ([release notes](https://github.com/hapijs/hapi/issues?labels=release+notes&page=1&state=closed)) 
+Development version: **15.1.x** ([release notes](https://github.com/hapijs/hapi/issues?labels=release+notes&page=1&state=closed)) 
 [![Build Status](https://secure.travis-ci.org/hapijs/hapi.svg?branch=master)](http://travis-ci.org/hapijs/hapi)
 
 For the latest updates, [change log](http://hapijs.com/updates), and release information visit [hapijs.com](http://hapijs.com) and follow [@hapijs](https://twitter.com/hapijs) on twitter. If you have questions, please open an issue in the

lib/plugin.js

@@ -262,7 +262,8 @@ internals.Plugin.prototype.register = function (plugins /*, [options], callback
 
         // Protect against multiple registrations
 
-        if (!item.connections) {
+        const connectionless = (item.connections === 'conditional' ? selection.connections.length === 0 : !item.connections);
+        if (connectionless) {
             if (this.root._registrations[item.name]) {
                 if (item.options.once) {
                     return next();
@@ -294,21 +295,21 @@ internals.Plugin.prototype.register = function (plugins /*, [options], callback
             }
 
             if (item.options.once &&
-                item.connections &&
+                !connectionless &&
                 !connections.length) {
 
                 return next();                                              // All the connections already registered
             }
         }
 
-        selection.connections = (item.connections ? connections : null);
+        selection.connections = (connectionless ? null : connections);
         selection._single();
 
         if (item.dependencies) {
             selection.dependency(item.dependencies);
         }
 
-        if (!item.connections) {
+        if (connectionless) {
             selection.connection = this.connection;
         }
 

lib/schema.js

@@ -341,7 +341,7 @@ internals.plugin = internals.register.keys({
             version: Joi.string(),
             multiple: Joi.boolean().default(false),
             dependencies: Joi.array().items(Joi.string()).single(),
-            connections: Joi.boolean().default(true),
+            connections: Joi.boolean().allow('conditional').default(true),
             once: Joi.boolean().valid(true)
         })
             .required()

package.json

@@ -2,7 +2,7 @@
   "name": "hapi",
   "description": "HTTP Server framework",
   "homepage": "http://hapijs.com",
-  "version": "15.0.4",
+  "version": "15.1.0",
   "repository": {
     "type": "git",
     "url": "git://github.com/hapijs/hapi"

test/plugin.js

@@ -1492,6 +1492,51 @@ describe('Plugin', () => {
             });
         });
 
+        it('register a conditional connectionless plugin (empty selection)', (done) => {
+
+            const test = function (srv, options, next) {
+
+                expect(srv.connections).to.be.null();
+                expect(srv.connection).to.be.a.function();
+                return next();
+            };
+
+            test.attributes = {
+                name: 'test',
+                connections: 'conditional'
+            };
+
+            const server = new Hapi.Server();
+            server.register(test, (err) => {
+
+                expect(err).to.not.exist();
+                done();
+            });
+        });
+
+        it('register a conditional connectionless plugin (with selection)', (done) => {
+
+            const test = function (srv, options, next) {
+
+                expect(srv.connections).to.exist();
+                expect(srv.connection).to.not.exist();
+                return next();
+            };
+
+            test.attributes = {
+                name: 'test',
+                connections: 'conditional'
+            };
+
+            const server = new Hapi.Server();
+            server.connection();
+            server.register(test, (err) => {
+
+                expect(err).to.not.exist();
+                done();
+            });
+        });
+
         it('register a plugin once per connection (no selection left)', (done) => {
 
             let count = 0;