diff --git a/src/plugins/elasticsearch/index.js b/src/plugins/elasticsearch/index.js
index 76a44285d9ef8..c60f56f88b6df 100644
--- a/src/plugins/elasticsearch/index.js
+++ b/src/plugins/elasticsearch/index.js
@@ -33,6 +33,16 @@ module.exports = function ({ Plugin }) {
       }).default();
     },
 
+    uiExports: {
+      injectDefaultVars(server, options) {
+        return {
+          esRequestTimeout: options.requestTimeout,
+          esShardTimeout: options.shardTimeout,
+          esApiVersion: options.apiVersion,
+        };
+      }
+    },
+
     init(server, options) {
       const kibanaIndex = server.config().get('kibana.index');
 
diff --git a/src/plugins/elasticsearch/lib/__tests__/routes.js b/src/plugins/elasticsearch/lib/__tests__/routes.js
index c4bacca30d553..34a75f6a29814 100644
--- a/src/plugins/elasticsearch/lib/__tests__/routes.js
+++ b/src/plugins/elasticsearch/lib/__tests__/routes.js
@@ -1,9 +1,8 @@
 import expect from 'expect.js';
-import util from 'util';
-import * as kbnTestServer from '../../../../../test/utils/kbn_server';
-
-const format = util.format;
+import { format } from 'util';
 
+import * as kbnTestServer from '../../../../../test/utils/kbn_server';
+import fromRoot from '../../../../utils/from_root';
 
 describe('plugins/elasticsearch', function () {
   describe('routes', function () {
@@ -13,7 +12,13 @@ describe('plugins/elasticsearch', function () {
     before(function () {
       this.timeout(60000); // sometimes waiting for server takes longer than 10
 
-      kbnServer = kbnTestServer.createServer();
+      kbnServer = kbnTestServer.createServer({
+        plugins: {
+          scanDirs: [
+            fromRoot('src/plugins')
+          ]
+        }
+      });
       return kbnServer.ready()
       .then(() => kbnServer.server.plugins.elasticsearch.waitUntilReady());
     });
diff --git a/src/plugins/kibana/index.js b/src/plugins/kibana/index.js
index 88ab65eb3d38a..f64fbaf4ed80d 100644
--- a/src/plugins/kibana/index.js
+++ b/src/plugins/kibana/index.js
@@ -34,7 +34,13 @@ module.exports = function (kibana) {
             kbnDefaultAppId: config.get('kibana.defaultAppId')
           };
         }
-      }
+      },
+
+      injectDefaultVars(server, options) {
+        return {
+          kbnIndex: options.index
+        };
+      },
     },
 
     init: function (server, options) {
diff --git a/src/server/plugins/plugin.js b/src/server/plugins/plugin.js
index 2b504142a86ce..18c7786c15720 100644
--- a/src/server/plugins/plugin.js
+++ b/src/server/plugins/plugin.js
@@ -1,9 +1,11 @@
 import _ from 'lodash';
 import Joi from 'joi';
-import { attempt, fromNode } from 'bluebird';
+import Bluebird, { attempt, fromNode } from 'bluebird';
 import { basename, resolve } from 'path';
 import { inherits } from 'util';
 
+const extendInitFns = Symbol('extend plugin initialization');
+
 const defaultConfigSchema = Joi.object({
   enabled: Joi.boolean().default(true)
 }).default();
@@ -57,6 +59,7 @@ module.exports = class Plugin {
     this.externalInit = opts.init || _.noop;
     this.getConfigSchema = opts.config || _.noop;
     this.init = _.once(this.init);
+    this[extendInitFns] = [];
 
     if (opts.publicDir === false) {
       this.publicDir = null;
@@ -98,14 +101,12 @@ module.exports = class Plugin {
     let { config } = kbnServer;
 
     // setup the hapi register function and get on with it
-    let register = (server, options, next) => {
+    const asyncRegister = async (server, options) => {
       this.server = server;
 
-      // bind the server and options to all
-      // apps created by this plugin
-      for (let app of this.apps) {
-        app.getInjectedVars = _.partial(app.getInjectedVars, server, options);
-      }
+      await Promise.all(this[extendInitFns].map(async fn => {
+        await fn.call(this, server, options);
+      }));
 
       server.log(['plugins', 'debug'], {
         tmpl: 'Initializing plugin <%= plugin.id %>',
@@ -119,7 +120,11 @@ module.exports = class Plugin {
       this.status = kbnServer.status.create(`plugin:${this.id}`);
       server.expose('status', this.status);
 
-      attempt(this.externalInit, [server, options], this).nodeify(next);
+      return await attempt(this.externalInit, [server, options], this);
+    };
+
+    const register = (server, options, next) => {
+      Bluebird.resolve(asyncRegister(server, options)).nodeify(next);
     };
 
     register.attributes = { name: id, version: version };
@@ -138,6 +143,10 @@ module.exports = class Plugin {
     }
   }
 
+  extendInit(fn) {
+    this[extendInitFns].push(fn);
+  }
+
   toJSON() {
     return this.pkg;
   }
diff --git a/src/ui/__tests__/fixtures/plugin_async_foo/index.js b/src/ui/__tests__/fixtures/plugin_async_foo/index.js
new file mode 100644
index 0000000000000..a0cd8887bbed0
--- /dev/null
+++ b/src/ui/__tests__/fixtures/plugin_async_foo/index.js
@@ -0,0 +1,18 @@
+import Bluebird from 'bluebird';
+
+export default kibana => new kibana.Plugin({
+  config(Joi) {
+    return Joi.object().keys({
+      enabled: Joi.boolean().default(true),
+      delay: Joi.number().required(),
+      shared: Joi.string(),
+    }).default();
+  },
+
+  uiExports: {
+    async injectDefaultVars(server, options) {
+      await Bluebird.delay(options.delay);
+      return { shared: options.shared };
+    }
+  }
+});
diff --git a/src/ui/__tests__/fixtures/plugin_async_foo/package.json b/src/ui/__tests__/fixtures/plugin_async_foo/package.json
new file mode 100644
index 0000000000000..4ad7dda995ca5
--- /dev/null
+++ b/src/ui/__tests__/fixtures/plugin_async_foo/package.json
@@ -0,0 +1,4 @@
+{
+  "name": "plugin_async_foo",
+  "version": "0.0.0"
+}
diff --git a/src/ui/__tests__/fixtures/plugin_bar/index.js b/src/ui/__tests__/fixtures/plugin_bar/index.js
new file mode 100644
index 0000000000000..59c5556444496
--- /dev/null
+++ b/src/ui/__tests__/fixtures/plugin_bar/index.js
@@ -0,0 +1,14 @@
+export default kibana => new kibana.Plugin({
+  config(Joi) {
+    return Joi.object().keys({
+      enabled: Joi.boolean().default(true),
+      shared: Joi.string()
+    }).default();
+  },
+
+  uiExports: {
+    injectDefaultVars(server, options) {
+      return { shared: options.shared };
+    }
+  }
+});
diff --git a/src/ui/__tests__/fixtures/plugin_bar/package.json b/src/ui/__tests__/fixtures/plugin_bar/package.json
new file mode 100644
index 0000000000000..bfc5da0182266
--- /dev/null
+++ b/src/ui/__tests__/fixtures/plugin_bar/package.json
@@ -0,0 +1,4 @@
+{
+  "name": "plugin_bar",
+  "version": "0.0.0"
+}
diff --git a/src/ui/__tests__/fixtures/plugin_foo/index.js b/src/ui/__tests__/fixtures/plugin_foo/index.js
new file mode 100644
index 0000000000000..59c5556444496
--- /dev/null
+++ b/src/ui/__tests__/fixtures/plugin_foo/index.js
@@ -0,0 +1,14 @@
+export default kibana => new kibana.Plugin({
+  config(Joi) {
+    return Joi.object().keys({
+      enabled: Joi.boolean().default(true),
+      shared: Joi.string()
+    }).default();
+  },
+
+  uiExports: {
+    injectDefaultVars(server, options) {
+      return { shared: options.shared };
+    }
+  }
+});
diff --git a/src/ui/__tests__/fixtures/plugin_foo/package.json b/src/ui/__tests__/fixtures/plugin_foo/package.json
new file mode 100644
index 0000000000000..6a73b89110ae9
--- /dev/null
+++ b/src/ui/__tests__/fixtures/plugin_foo/package.json
@@ -0,0 +1,4 @@
+{
+  "name": "plugin_foo",
+  "version": "0.0.0"
+}
diff --git a/src/ui/__tests__/ui_exports.js b/src/ui/__tests__/ui_exports.js
index 678d88d839835..adf561822e947 100644
--- a/src/ui/__tests__/ui_exports.js
+++ b/src/ui/__tests__/ui_exports.js
@@ -1,6 +1,8 @@
 import expect from 'expect.js';
+import { resolve } from 'path';
 
 import UiExports from '../ui_exports';
+import * as kbnTestServer from '../../../test/utils/kbn_server';
 
 describe('UiExports', function () {
   describe('#find()', function () {
@@ -23,4 +25,83 @@ describe('UiExports', function () {
       expect(uiExports.find(['foo', 'bar'])).to.eql(['a', 'b', 'c']);
     });
   });
+//
+  describe('#defaultInjectedVars', function () {
+    context('two plugins, two sync', function () {
+      this.slow(10000);
+      this.timeout(60000);
+
+      let kbnServer;
+      before(async function () {
+        kbnServer = kbnTestServer.createServer({
+          plugins: {
+            paths: [
+              resolve(__dirname, 'fixtures/plugin_bar'),
+              resolve(__dirname, 'fixtures/plugin_foo')
+            ]
+          },
+
+          plugin_foo: {
+            shared: 'foo'
+          },
+
+          plugin_bar: {
+            shared: 'bar'
+          }
+        });
+
+        await kbnServer.ready();
+      });
+
+      after(async function () {
+        await kbnServer.close();
+      });
+
+      it('merges the two plugins in the order they are loaded', function () {
+        expect(kbnServer.uiExports.defaultInjectedVars).to.eql({
+          shared: 'foo'
+        });
+      });
+    });
+
+    context('two plugins, one async', function () {
+      this.slow(10000);
+      this.timeout(60000);
+
+      let kbnServer;
+      before(async function () {
+        kbnServer = kbnTestServer.createServer({
+          plugins: {
+            scanDirs: [],
+            paths: [
+              resolve(__dirname, 'fixtures/plugin_async_foo'),
+              resolve(__dirname, 'fixtures/plugin_foo')
+            ]
+          },
+
+          plugin_async_foo: {
+            delay: 500,
+            shared: 'foo'
+          },
+
+          plugin_bar: {
+            shared: 'bar'
+          }
+        });
+
+        await kbnServer.ready();
+      });
+
+      after(async function () {
+        await kbnServer.close();
+      });
+
+      it('merges the two plugins in the order they are loaded', function () {
+        // even though plugin_async_foo loads 500ms later, it is still "first" to merge
+        expect(kbnServer.uiExports.defaultInjectedVars).to.eql({
+          shared: 'foo'
+        });
+      });
+    });
+  });
 });
diff --git a/src/ui/index.js b/src/ui/index.js
index 6dd0407323367..b6a8350f54323 100644
--- a/src/ui/index.js
+++ b/src/ui/index.js
@@ -59,16 +59,6 @@ module.exports = async (kbnServer, server, config) => {
     }
   });
 
-  const defaultInjectedVars = {};
-  if (config.has('kibana')) {
-    defaultInjectedVars.kbnIndex = config.get('kibana.index');
-  }
-  if (config.has('elasticsearch')) {
-    defaultInjectedVars.esRequestTimeout = config.get('elasticsearch.requestTimeout');
-    defaultInjectedVars.esShardTimeout = config.get('elasticsearch.shardTimeout');
-    defaultInjectedVars.esApiVersion = config.get('elasticsearch.apiVersion');
-  }
-
   server.decorate('reply', 'renderApp', function (app) {
     const payload = {
       app: app,
@@ -77,7 +67,7 @@ module.exports = async (kbnServer, server, config) => {
       buildNum: config.get('pkg.buildNum'),
       buildSha: config.get('pkg.buildSha'),
       basePath: config.get('server.basePath'),
-      vars: defaults(app.getInjectedVars() || {}, defaultInjectedVars),
+      vars: defaults(app.getInjectedVars() || {}, uiExports.defaultInjectedVars),
     };
 
     return this.view(app.templateName, {
diff --git a/src/ui/ui_exports.js b/src/ui/ui_exports.js
index da5edef1a8f03..5048d576e989a 100644
--- a/src/ui/ui_exports.js
+++ b/src/ui/ui_exports.js
@@ -11,6 +11,7 @@ class UiExports {
     this.exportConsumer = _.memoize(this.exportConsumer);
     this.consumers = [];
     this.bundleProviders = [];
+    this.defaultInjectedVars = {};
   }
 
   consumePlugin(plugin) {
@@ -53,6 +54,12 @@ class UiExports {
               id: plugin.id,
               urlBasePath: this.urlBasePath
             }));
+
+            plugin.extendInit((server, options) => { // eslint-disable-line no-loop-func
+              const wrapped = app.getInjectedVars;
+              app.getInjectedVars = () => wrapped.call(plugin, server, options);
+            });
+
             plugin.apps.add(app);
           }
         };
@@ -80,6 +87,13 @@ class UiExports {
             this.aliases[adhocType] = _.union(this.aliases[adhocType] || [], spec);
           });
         };
+
+      case 'injectDefaultVars':
+        return (plugin, injector) => {
+          plugin.extendInit(async (server, options) => {
+            _.merge(this.defaultInjectedVars, await injector.call(plugin, server, options));
+          });
+        };
     }
   }
 
diff --git a/test/utils/kbn_server.js b/test/utils/kbn_server.js
index 6f854283e8b0b..52e243142465b 100644
--- a/test/utils/kbn_server.js
+++ b/test/utils/kbn_server.js
@@ -3,7 +3,6 @@ import { defaultsDeep, set } from 'lodash';
 import { header as basicAuthHeader } from './base_auth';
 import { kibanaUser, kibanaServer } from '../shield';
 import KbnServer from '../../src/server/kbn_server';
-import fromRoot from '../../src/utils/from_root';
 import serverConfig from '../server_config';
 
 const SERVER_DEFAULTS = {
@@ -16,11 +15,7 @@ const SERVER_DEFAULTS = {
   logging: {
     quiet: true
   },
-  plugins: {
-    scanDirs: [
-      fromRoot('src/plugins')
-    ]
-  },
+  plugins: {},
   optimize: {
     enabled: false
   },