feat(metrics): Add metrics when the bounce check blocks an email

This change also includes a change to bounces.js that isn't used in the
metrics along with tests because it was part of a footgun that I ran
into while working on this patch.

Fixes FXA-10964

Author: jonalmeida

packages/fxa-auth-server/lib/bounces.js

@@ -71,6 +71,7 @@ module.exports = (config, db) => {
         tally.count++;
       }
     });
+    return tallies;
   }
 
   function disabled() {

packages/fxa-auth-server/lib/senders/email.js

@@ -28,7 +28,7 @@ const UTM_PREFIX = 'fx-';
 const X_SES_CONFIGURATION_SET = 'X-SES-CONFIGURATION-SET';
 const X_SES_MESSAGE_TAGS = 'X-SES-MESSAGE-TAGS';
 
-module.exports = function (log, config, bounces) {
+module.exports = function (log, config, bounces, statsd) {
   const oauthClientInfo = require('./oauth_client_info')(log, config);
   const verificationReminders = require('../verification-reminders')(
     log,
@@ -461,6 +461,9 @@ module.exports = function (log, config, bounces) {
     try {
       await bounces.check(to, template);
     } catch (err) {
+      const tags = { template, error: err.errno };
+      statsd.increment('email.bounce.limit', tags);
+
       log.error('email.bounce.limit', {
         err: err.message,
         errno: err.errno,

packages/fxa-auth-server/lib/senders/index.js

@@ -14,7 +14,7 @@ module.exports = async (
   sender // This is only used in tests
 ) => {
   const defaultLanguage = config.i18n.defaultLanguage;
-  const Mailer = createMailer(log, config, bounces);
+  const Mailer = createMailer(log, config, bounces, statsd);
 
   async function createSenders() {
     return {

packages/fxa-auth-server/test/local/bounces.js

@@ -190,4 +190,34 @@ describe('bounces', () => {
     await bounces.check(EMAIL, 'recovery');
     assert.equal(db.emailBounces.callCount, 0);
   });
+
+  it('get results from bounce checks', async () => {
+    const conf = Object.assign({}, config);
+    const latestBounce = Date.now() - 20000;
+    conf.smtp = {
+      bounces: {
+        enabled: true,
+        complaint: {
+          0: 5000,
+          1: 50000,
+        },
+      },
+    };
+    const db = {
+      emailBounces: sinon.spy(() =>
+        Promise.resolve([
+          {
+            bounceType: BOUNCE_TYPE_COMPLAINT,
+            createdAt: latestBounce,
+          },
+        ])
+      ),
+    };
+    return createBounces(conf, db)
+      .check(EMAIL)
+      .then((tallies) => {
+        assert.equal(tallies[BOUNCE_TYPE_COMPLAINT].count, 1);
+        assert.equal(tallies[BOUNCE_TYPE_COMPLAINT].latest, latestBounce);
+      });
+  });
 });

packages/fxa-auth-server/test/local/senders/emails.ts

@@ -17,6 +17,8 @@ import {
   MOCK_DEVICE_OS,
   MOCK_DEVICE_OS_VERSION,
 } from '../../../lib/senders/emails/partials/userDevice/mocks';
+import AppError from '../../../lib/error';
+import { AUTH_SERVER_ERRNOS } from 'fxa-shared/lib/errors';
 
 const moment = require('moment-timezone');
 const config = require(`${ROOT_DIR}/config`).default.getProperties();
@@ -3213,6 +3215,96 @@ describe('mailer constructor:', () => {
   });
 });
 
+describe('mailer bounce throws exceptions', () => {
+  let mailer: Record<any, any>, mockStatsd: any;
+
+  before(async () => {
+    mockStatsd = mocks.mockStatsd();
+    mailer = await setup(
+      mocks.mockLog(),
+      config,
+      {},
+      'en',
+      null,
+      {
+        check: async () => {
+          throw AppError.emailComplaint(10);
+        },
+      },
+      mockStatsd
+    );
+
+    mailer.localize = () => ({});
+  });
+
+  it('email bounce exceptions increment stats', () => {
+    const message = {
+      email: '[email protected]',
+      flowId: 'wibble',
+      subject: 'subject',
+      template: 'inactive-first-email',
+      uid: 'foo',
+    };
+
+    // We shouldn't get to this call, so we fail it.
+    sinon.stub(mailer.mailer, 'sendMail').callsFake((_config, cb: any) => {
+      cb(new Error('Fail'));
+    });
+
+    return mailer.send(message).then(() => {
+      const spiedStatsd = mockStatsd.increment.getCalls()[0];
+
+      assert.equal(spiedStatsd.args[0], 'email.bounce.limit');
+      assert.equal(spiedStatsd.args[1].template, 'inactive-first-email');
+      assert.equal(
+        spiedStatsd.args[1].error,
+        AUTH_SERVER_ERRNOS.BOUNCE_COMPLAINT
+      );
+    });
+  });
+});
+
+describe('mailer bounces succeed', () => {
+  let mailer: Record<any, any>, mockStatsd: any;
+  const mockLog = mocks.mockLog();
+
+  before(async () => {
+    mockStatsd = mocks.mockStatsd();
+    mailer = await setup(
+      mockLog,
+      config,
+      {},
+      'en',
+      null,
+      {
+        check: async () => Promise.resolve(),
+      },
+      mockStatsd
+    );
+
+    mailer.localize = () => ({});
+    sinon.stub(mailer.mailer, 'sendMail').callsFake((_config, cb: any) => {
+      cb(null, { resp: 'ok' });
+    });
+  });
+
+  it('email bounce check sends mail', () => {
+    const message = {
+      email: '[email protected]',
+      flowId: 'wibble',
+      subject: 'subject',
+      template: 'inactive-first-email',
+      uid: 'foo',
+    };
+
+    return mailer.send(message).then((resp) => {
+      // assert that the log in the final 'sendMail' function is called.
+      const emailEventLog = mockLog.debug.getCalls()[1];
+      assert.equal(emailEventLog.args[0], 'mailer.send.1');
+    });
+  });
+});
+
 function sesMessageTagsHeaderValue(templateName: string, serviceName?: any) {
   return `messageType=fxa-${templateName}, app=fxa, service=${
     serviceName || 'fxa-auth-server'
@@ -3284,14 +3376,17 @@ async function setup(
   config: Record<any, any>,
   mocks: any,
   locale = 'en',
-  sender: any = null
+  sender: any = null,
+  bounces: any = null,
+  statsd: any = null
 ) {
   const Mailer = proxyquire(`${ROOT_DIR}/lib/senders/email`, mocks)(
     log,
     config,
-    {
+    bounces || {
       check: () => Promise.resolve(),
-    }
+    },
+    statsd
   );
   return new Mailer(config.smtp, sender);
 }