feat(server): add SSR React rendering summary metric (#996)

.prettierrc

@@ -0,0 +1,5 @@
+{
+  "editorconfig": true,
+  "singleQuote": true,
+  "trailingComma": "es5"
+}

__tests__/integration/__snapshots__/one-app.spec.js.snap

@@ -72,6 +72,7 @@ Array [
   "oneapp_holocron_module_map_poll_wait_seconds",
   "oneapp_holocron_module_map_updated_total",
   "oneapp_intl_cache_size_total",
+  "oneapp_ssr_react_rendering_seconds",
   "oneapp_version_info",
   "process_cpu_seconds_total",
   "process_cpu_system_seconds_total",

__tests__/server/metrics/summaries.spec.js

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2023 American Express Travel Related Services Company, Inc.
+ *
+ * Licensed 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.
+ */
+
+describe('summaries', () => {
+  let Summary;
+
+  function load() {
+    jest.resetModules();
+
+    jest.mock('prom-client');
+    ({ Summary } = require('prom-client'));
+
+    return require('../../../src/server/metrics/summaries');
+  }
+
+  describe('createSummary', () => {
+    it('is a function', () => {
+      const { createSummary } = load();
+      expect(createSummary).toBeInstanceOf(Function);
+    });
+
+    it('creates a summary with the options', () => {
+      const { createSummary } = load();
+      createSummary({ name: 'yup' });
+      expect(Summary).toHaveBeenCalledTimes(1);
+      const summary = Summary.mock.instances[0];
+      expect(summary).toBeInstanceOf(Summary);
+    });
+
+    it('does not create a new summary if one with the same name already exists', () => {
+      const { createSummary } = load();
+      createSummary({ name: 'yup' });
+      expect(Summary).toHaveBeenCalledTimes(1);
+      createSummary({ name: 'yup' });
+      expect(Summary).toHaveBeenCalledTimes(1);
+    });
+  });
+
+  describe('startSummaryTimer', () => {
+    it('is a function', () => {
+      const { startSummaryTimer } = load();
+      expect(startSummaryTimer).toBeInstanceOf(Function);
+    });
+
+    it('throws an error if the summary does not exist', () => {
+      const { startSummaryTimer } = load();
+      expect(() => startSummaryTimer('nope')).toThrowErrorMatchingInlineSnapshot(
+        '"unable to find summary nope, please create it first"'
+      );
+    });
+
+    it('calls the startTimer method of the summary', () => {
+      const { createSummary, startSummaryTimer } = load();
+      createSummary({ name: 'yup' });
+      const summary = Summary.mock.instances[0];
+      startSummaryTimer('yup');
+      expect(summary.startTimer).toHaveBeenCalledTimes(1);
+    });
+
+    it('calls the startTimer method of the summary with the arguments', () => {
+      const { createSummary, startSummaryTimer } = load();
+      createSummary({ name: 'yup' });
+      const summary = Summary.mock.instances[0];
+      startSummaryTimer('yup', 1, 'two', [null, null, null]);
+      expect(summary.startTimer).toHaveBeenCalledTimes(1);
+      expect(summary.startTimer).toHaveBeenCalledWith(1, 'two', [null, null, null]);
+    });
+  });
+});

src/server/metrics/index.js

@@ -16,10 +16,12 @@
 
 import { incrementCounter } from './counters';
 import { incrementGauge, setGauge, resetGauge } from './gauges';
+import { startSummaryTimer } from './summaries';
 
 import holocron from './holocron';
 import intlCache from './intl-cache';
 import * as appVersion from './app-version';
+import ssr from './ssr';
 
 export {
   // counters
@@ -30,8 +32,12 @@ export {
   setGauge,
   resetGauge,
 
+  // summaries
+  startSummaryTimer,
+
   // metrics
   holocron,
   appVersion,
   intlCache,
+  ssr,
 };

src/server/metrics/ssr.js

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2023 American Express Travel Related Services Company, Inc.
+ *
+ * Licensed 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.
+ */
+
+import { createSummary } from './summaries';
+
+import createMetricNamespace from './create-metric-namespace';
+
+const ssrNamespace = createMetricNamespace('ssr');
+
+createSummary({
+  name: ssrNamespace('react_rendering', 'seconds'),
+  help: 'time taken by React to render HTML',
+  labelNames: ['renderMethodName'],
+});
+
+export default ssrNamespace.getMetricNames();

src/server/metrics/summaries.js

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2023 American Express Travel Related Services Company, Inc.
+ *
+ * Licensed 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.
+ */
+
+import { Summary } from 'prom-client';
+
+const summaries = {};
+
+function createSummary(opts) {
+  const { name } = opts;
+  if (summaries[name]) {
+    return;
+  }
+  summaries[name] = new Summary(opts);
+}
+
+function startSummaryTimer(name, ...args) {
+  if (!summaries[name]) {
+    throw new Error(`unable to find summary ${name}, please create it first`);
+  }
+  return summaries[name].startTimer(...args);
+}
+
+export {
+  createSummary,
+  startSummaryTimer,
+};

src/server/middleware/createRequestHtmlFragment.jsx

@@ -14,13 +14,20 @@
  * permissions and limitations under the License.
  */
 
-import React from 'react';
-import { Provider } from 'react-redux';
 import url, { Url } from 'url';
 import util from 'util';
+
+import React from 'react';
+import { Provider } from 'react-redux';
 import { RouterContext, matchPromise } from '@americanexpress/one-app-router';
 import { composeModules } from 'holocron';
+
 import createCircuitBreaker from '../utils/createCircuitBreaker';
+import {
+  startSummaryTimer,
+
+  ssr as ssrMetrics,
+} from '../metrics';
 
 import {
   getRenderMethodName,
@@ -111,17 +118,21 @@ export default function createRequestHtmlFragment({ createRoutes }) {
         }
       }
 
-      const renderMethod = getRenderMethodName(state) === 'renderForStaticMarkup'
+      const renderMethodName = getRenderMethodName(state);
+      const renderMethod = renderMethodName === 'renderForStaticMarkup'
         ? renderForStaticMarkup
         : renderForString;
 
+      const finishRenderTimer = startSummaryTimer(ssrMetrics.reactRendering, { renderMethodName });
       /* eslint-disable react/jsx-props-no-spreading */
       const { renderedString, helmetInfo } = renderMethod(
         <Provider store={store}>
           <RouterContext {...renderProps} />
         </Provider>
       );
       /* eslint-ensable react/jsx-props-no-spreading */
+      finishRenderTimer();
+
       req.appHtml = renderedString;
       req.helmetInfo = helmetInfo;
     } catch (err) {