From ffacd65df492f99d35930f78d44e0910a89a971f Mon Sep 17 00:00:00 2001
From: restrry <restrry@gmail.com>
Date: Tue, 29 Sep 2020 15:52:52 +0300
Subject: [PATCH] load apm-agent-lazily

---
 src/core/public/apm_system.ts    | 75 ++++++++++++++++++++++++++++++++
 src/core/public/kbn_bootstrap.ts | 65 +++++++++------------------
 2 files changed, 95 insertions(+), 45 deletions(-)
 create mode 100644 src/core/public/apm_system.ts

diff --git a/src/core/public/apm_system.ts b/src/core/public/apm_system.ts
new file mode 100644
index 0000000000000..0a18f02c97293
--- /dev/null
+++ b/src/core/public/apm_system.ts
@@ -0,0 +1,75 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/**
+ * This is the entry point used to boot the frontend when serving a application
+ * that lives in the Kibana Platform.
+ *
+ * Any changes to this file should be kept in sync with
+ * src/legacy/ui/ui_bundles/app_entry_template.js
+ */
+import type { InternalApplicationStart } from './application';
+
+interface ApmConfig {
+  // AgentConfigOptions is not exported from @elastic/apm-rum
+  globalLabels?: Record<string, string>;
+}
+
+interface StartDeps {
+  application: InternalApplicationStart;
+}
+
+export class ApmSystem {
+  private readonly enabled: boolean;
+  /**
+   * `apmConfig` would be populated with relevant APM RUM agent
+   * configuration if server is started with `ELASTIC_APM_ACTIVE=true`
+   */
+  constructor(private readonly apmConfig?: ApmConfig) {
+    this.enabled = process.env.IS_KIBANA_DISTRIBUTABLE !== 'true' && apmConfig != null;
+  }
+
+  async setup() {
+    if (!this.enabled) return;
+    const { init, apm } = await import('@elastic/apm-rum');
+    const { globalLabels, ...apmConfig } = this.apmConfig!;
+    if (globalLabels) {
+      apm.addLabels(globalLabels);
+    }
+
+    init(apmConfig);
+  }
+
+  async start(start?: StartDeps) {
+    if (!this.enabled || !start) return;
+    /**
+     * Register listeners for navigation changes and capture them as
+     * route-change transactions after Kibana app is bootstrapped
+     */
+    start.application.currentAppId$.subscribe((appId) => {
+      const apmInstance = (window as any).elasticApm;
+      if (appId && apmInstance && typeof apmInstance.startTransaction === 'function') {
+        apmInstance.startTransaction(`/app/${appId}`, 'route-change', {
+          managed: true,
+          canReuse: true,
+        });
+      }
+    });
+  }
+}
diff --git a/src/core/public/kbn_bootstrap.ts b/src/core/public/kbn_bootstrap.ts
index a108b5aaa47ec..e0a91928d9e08 100644
--- a/src/core/public/kbn_bootstrap.ts
+++ b/src/core/public/kbn_bootstrap.ts
@@ -27,60 +27,35 @@
 
 import { i18n } from '@kbn/i18n';
 import { CoreSystem } from './core_system';
+import { ApmSystem } from './apm_system';
 
 /** @internal */
-export function __kbnBootstrap__() {
+export async function __kbnBootstrap__() {
   const injectedMetadata = JSON.parse(
     document.querySelector('kbn-injected-metadata')!.getAttribute('data')!
   );
 
-  /**
-   * `apmConfig` would be populated with relavant APM RUM agent
-   * configuration if server is started with `ELASTIC_APM_ACTIVE=true`
-   */
-  const apmConfig = injectedMetadata.vars.apmConfig;
-  const APM_ENABLED = process.env.IS_KIBANA_DISTRIBUTABLE !== 'true' && apmConfig != null;
+  const apmSystem = new ApmSystem(injectedMetadata.vars.apmConfig);
+  await apmSystem.setup();
 
-  if (APM_ENABLED) {
-    // eslint-disable-next-line @typescript-eslint/no-var-requires
-    const { init, apm } = require('@elastic/apm-rum');
-    if (apmConfig.globalLabels) {
-      apm.addLabels(apmConfig.globalLabels);
-    }
-    init(apmConfig);
+  let i18nError: Error | undefined;
+  try {
+    await i18n.load(injectedMetadata.i18n.translationsUrl);
+  } catch (error) {
+    i18nError = error;
   }
 
-  i18n
-    .load(injectedMetadata.i18n.translationsUrl)
-    .catch((e) => e)
-    .then(async (i18nError) => {
-      const coreSystem = new CoreSystem({
-        injectedMetadata,
-        rootDomElement: document.body,
-        browserSupportsCsp: !(window as any).__kbnCspNotEnforced__,
-      });
+  const coreSystem = new CoreSystem({
+    injectedMetadata,
+    rootDomElement: document.body,
+    browserSupportsCsp: !(window as any).__kbnCspNotEnforced__,
+  });
 
-      const setup = await coreSystem.setup();
-      if (i18nError && setup) {
-        setup.fatalErrors.add(i18nError);
-      }
-
-      const start = await coreSystem.start();
+  const setup = await coreSystem.setup();
+  if (i18nError && setup) {
+    setup.fatalErrors.add(i18nError);
+  }
 
-      if (APM_ENABLED && start) {
-        /**
-         * Register listeners for navigation changes and capture them as
-         * route-change transactions after Kibana app is bootstrapped
-         */
-        start.application.currentAppId$.subscribe((appId) => {
-          const apmInstance = (window as any).elasticApm;
-          if (appId && apmInstance && typeof apmInstance.startTransaction === 'function') {
-            apmInstance.startTransaction(`/app/${appId}`, 'route-change', {
-              managed: true,
-              canReuse: true,
-            });
-          }
-        });
-      }
-    });
+  const start = await coreSystem.start();
+  await apmSystem.start(start);
 }