feat: use 2 nodemailer clients

__tests__/e2e/setup/.test-env

@@ -67,6 +67,12 @@ SESSION_SECRET=sandcrawler-138577
 SES_PORT=1025 
 SES_HOST=0.0.0.0
 
+# TODO #130 Remove these when SES migration is over (opengovsg/formsg-private#130)
+SES_PORT_US=1025
+SES_HOST_US=0.0.0.0
+SES_PORT_SG=1025
+SES_HOST_SG=0.0.0.0
+
 SERVICES=s3
 
 IMAGE_S3_BUCKET=local-image-bucket

src/app/config/config.ts

@@ -122,7 +122,8 @@ const dbConfig: DbConfig = {
   },
 }
 
-const mailConfig: MailConfig = (function () {
+// TODO #130 Delete this mail config once SES migration is over (opengovsg/formsg-private#130)
+const mailConfig_us: MailConfig = (function () {
   const mailFrom = basicVars.mail.from
   const official = basicVars.mail.official
   const mailer = {
@@ -133,12 +134,12 @@ const mailConfig: MailConfig = (function () {
   let transporter: Mail
   if (!isDev) {
     const options: SMTPPool.Options = {
-      host: prodOnlyVars.host,
+      host: prodOnlyVars.host_us,
       auth: {
-        user: prodOnlyVars.user,
-        pass: prodOnlyVars.pass,
+        user: prodOnlyVars.user_us,
+        pass: prodOnlyVars.pass_us,
       },
-      port: prodOnlyVars.port,
+      port: prodOnlyVars.port_us,
       // Options as advised from https://nodemailer.com/usage/bulk-mail/
       // pool connections instead of creating fresh one for each email
       pool: true,
@@ -155,8 +156,56 @@ const mailConfig: MailConfig = (function () {
     transporter = nodemailer.createTransport(options)
   } else {
     transporter = nodemailer.createTransport({
-      port: prodOnlyVars.port,
-      host: prodOnlyVars.host,
+      port: prodOnlyVars.port_us,
+      host: prodOnlyVars.host_us,
+      ignoreTLS: true,
+    })
+  }
+
+  return {
+    mailFrom,
+    official,
+    mailer,
+    transporter,
+  }
+})()
+
+// TODO #130 Use this mail config when SES migration is over, after renaming env vars back to without _sg suffix (opengovsg/formsg-private#130)
+const mailConfig_sg: MailConfig = (function () {
+  const mailFrom = basicVars.mail.from
+  const official = basicVars.mail.official
+  const mailer = {
+    from: `${basicVars.appConfig.title} <${mailFrom}>`,
+  }
+
+  // Creating mail transport
+  let transporter: Mail
+  if (!isDev) {
+    const options: SMTPPool.Options = {
+      host: prodOnlyVars.host_sg,
+      auth: {
+        user: prodOnlyVars.user_sg,
+        pass: prodOnlyVars.pass_sg,
+      },
+      port: prodOnlyVars.port_sg,
+      // Options as advised from https://nodemailer.com/usage/bulk-mail/
+      // pool connections instead of creating fresh one for each email
+      pool: true,
+      maxMessages: basicVars.mail.maxMessages,
+      maxConnections: basicVars.mail.maxConnections,
+      socketTimeout: basicVars.mail.socketTimeout,
+      // If set to true then logs to console. If value is not set or is false
+      // then nothing is logged.
+      logger: basicVars.mail.logger,
+      // If set to true, then logs SMTP traffic, otherwise logs only transaction
+      // events.
+      debug: basicVars.mail.debug,
+    }
+    transporter = nodemailer.createTransport(options)
+  } else {
+    transporter = nodemailer.createTransport({
+      port: prodOnlyVars.port_sg,
+      host: prodOnlyVars.host_sg,
       ignoreTLS: true,
     })
   }
@@ -207,7 +256,9 @@ const config: Config = {
   app: basicVars.appConfig,
   db: dbConfig,
   aws: awsConfig,
-  mail: mailConfig,
+  mail_us: mailConfig_us,
+  mail_sg: mailConfig_sg,
+  nodemailer_sg_warmup_start_date: prodOnlyVars.nodemailer_sg_warmup_start_date,
   cookieSettings,
   isDev,
   nodeEnv,

src/app/config/schema.ts

@@ -382,29 +382,30 @@ export const optionalVarsSchema: Schema<IOptionalVarsSchema> = {
 }
 
 export const prodOnlyVarsSchema: Schema<IProdOnlyVarsSchema> = {
-  port: {
+  // TODO #130 Delete these env vars when SES migration is over (opengovsg/formsg-private#130)
+  port_us: {
     doc: 'SMTP port number',
     format: 'port',
     default: null,
-    env: 'SES_PORT',
+    env: 'SES_PORT_US',
   },
-  host: {
+  host_us: {
     doc: 'SMTP hostname',
     format: String,
     default: null,
-    env: 'SES_HOST',
+    env: 'SES_HOST_US',
   },
-  user: {
+  user_us: {
     doc: 'SMTP username',
     format: String,
     default: null,
-    env: 'SES_USER',
+    env: 'SES_USER_US',
   },
-  pass: {
+  pass_us: {
     doc: 'SMTP password',
     format: String,
     default: null,
-    env: 'SES_PASS',
+    env: 'SES_PASS_US',
     sensitive: true,
   },
   dbHost: {
@@ -436,6 +437,39 @@ export const prodOnlyVarsSchema: Schema<IProdOnlyVarsSchema> = {
     env: 'DB_HOST',
     sensitive: true,
   },
+  // TODO #130 Rename these env vars to without the _sg suffix when SES migration is over (opengovsg/formsg-private#130)
+  port_sg: {
+    doc: 'SMTP port number',
+    format: 'port',
+    default: null,
+    env: 'SES_PORT_SG',
+  },
+  host_sg: {
+    doc: 'SMTP hostname',
+    format: String,
+    default: null,
+    env: 'SES_HOST_SG',
+  },
+  user_sg: {
+    doc: 'SMTP username',
+    format: String,
+    default: null,
+    env: 'SES_USER_SG',
+  },
+  pass_sg: {
+    doc: 'SMTP password',
+    format: String,
+    default: null,
+    env: 'SES_PASS_SG',
+    sensitive: true,
+  },
+  // TODO #130 Remove this when SES migration is over (opengovsg/formsg-private#130)
+  nodemailer_sg_warmup_start_date: {
+    doc: 'Date where SG nodemailer client will start sending emails',
+    format: String,
+    default: '2099-01-01T23:59:59+08:00',
+    env: 'NODEMAILER_SG_WARMUP_START_DATE',
+  },
 }
 
 export const loadS3BucketUrlSchema = ({

src/app/services/mail/__tests__/mail.service.spec.ts

@@ -54,7 +54,9 @@ describe('mail.service', () => {
   beforeEach(() => sendMailSpy.mockReset())
 
   const mailService = new MailService({
-    transporter: mockTransporter,
+    // Remove references to US when SES migration is over (opengovsg/formsg-private#130)
+    transporter_us: mockTransporter,
+    transporter_sg: mockTransporter,
     senderMail: MOCK_SENDER_EMAIL,
     officialMail: MOCK_SENDER_EMAIL,
     appName: MOCK_APP_NAME,
@@ -67,7 +69,9 @@ describe('mail.service', () => {
     it('should throw error when invalid senderMail param is passed', () => {
       // Arrange
       const invalidParams = {
-        transporter: mockTransporter,
+        // TODO #130 Remove references to US when SES migration is over (opengovsg/formsg-private#130)
+        transporter_us: mockTransporter,
+        transporter_sg: mockTransporter,
         senderMail: 'notAnEmail',
       }
       // Act + Assert

src/app/services/mail/mail.service.ts

@@ -64,6 +64,21 @@ const DEFAULT_RETRY_PARAMS: MailServiceParams['retryParams'] = {
   minTimeout: 5000,
 }
 
+// TODO #130 Delete references to US SES when SES migration is over (opengovsg/formsg-private#130)
+const START_TS = new Date(config.nodemailer_sg_warmup_start_date).getTime()
+const WARM_UP_DURATION = 6 * 7 * 24 * 60 * 60 * 1000 // 6 weeks
+
+const getWarmUpThreshold = () => {
+  // if START_TS is an empty string, set threshold to 0
+  if (isNaN(START_TS)) {
+    return 0
+  }
+  const now = Date.now()
+  const elapsed = Math.max(0, Math.min(now - START_TS, WARM_UP_DURATION))
+  const linear = elapsed / WARM_UP_DURATION
+  return linear * linear
+}
+
 export class MailService {
   /**
    * The application name to be shown in some sent emails' fields such as mail
@@ -76,9 +91,13 @@ export class MailService {
    */
   #appUrl: Required<MailServiceParams>['appUrl']
   /**
-   * The transporter to be used to send mail.
+   * The transporter to be used to send mail (SES in US).
+   */
+  #transporter_us: Required<MailServiceParams>['transporter_us']
+  /**
+   * The transporter to be used to send mail (SES in SG).
    */
-  #transporter: Required<MailServiceParams>['transporter']
+  #transporter_sg: Required<MailServiceParams>['transporter_sg']
   /**
    * The email string to denote the "from" field of the email.
    */
@@ -104,9 +123,10 @@ export class MailService {
   constructor({
     appName = config.app.title,
     appUrl = config.app.appUrl,
-    transporter = config.mail.transporter,
-    senderMail = config.mail.mailFrom,
-    officialMail = config.mail.official,
+    transporter_us = config.mail_us.transporter,
+    transporter_sg = config.mail_sg.transporter,
+    senderMail = config.mail_us.mailFrom,
+    officialMail = config.mail_us.official,
     retryParams = DEFAULT_RETRY_PARAMS,
   }: MailServiceParams = {}) {
     // Email validation
@@ -127,7 +147,8 @@ export class MailService {
     this.#appUrl = appUrl
     this.#senderMail = senderMail
     this.#senderFromString = `${appName} <${senderMail}>`
-    this.#transporter = transporter
+    this.#transporter_us = transporter_us
+    this.#transporter_sg = transporter_sg
     this.#officialMail = officialMail
     this.#retryParams = retryParams
   }
@@ -157,13 +178,27 @@ export class MailService {
       })
 
       try {
-        const info = await tracer.trace('nodemailer/sendMail', () =>
-          this.#transporter.sendMail(mail),
-        )
+        const rand = Math.random()
+        const threshold = getWarmUpThreshold()
+        const sendMailFromSG = rand < threshold
+        const info = await tracer.trace('nodemailer/sendMail', () => {
+          const span = tracer.scope().active()
+          if (span) span.setTag('ses.region', sendMailFromSG ? 'sg' : 'us')
+          return sendMailFromSG
+            ? this.#transporter_sg.sendMail(mail)
+            : this.#transporter_us.sendMail(mail)
+        })
 
+        const logNodemailerMeta = {
+          action: 'Nodemailer evaluation done',
+          sendMailFromSG: sendMailFromSG,
+          mathRandom: rand,
+          threshold: threshold,
+          sendFromSGStartDate: START_TS,
+        }
         logger.info({
           message: `Mail successfully sent on attempt ${attemptNum}`,
-          meta: { ...logMeta, info },
+          meta: { ...logMeta, info, ...logNodemailerMeta },
         })
 
         return true

src/app/services/mail/mail.types.ts

@@ -33,10 +33,12 @@ export type SendAutoReplyEmailsArgs = {
   autoReplyMailDatas: AutoReplyMailData[]
 }
 
+// TODO #130 Remove references to US SES when SES migration is over (opengovsg/formsg-private#130)
 export type MailServiceParams = {
   appName?: string
   appUrl?: string
-  transporter?: Mail
+  transporter_us?: Mail
+  transporter_sg?: Mail
   senderMail?: string
   officialMail?: string
   retryParams?: Partial<OperationOptions>

src/types/config.ts

@@ -69,7 +69,10 @@ export type Config = {
   app: AppConfig
   db: DbConfig
   aws: AwsConfig
-  mail: MailConfig
+  // TODO #130 Remove references to US SES when SES migration is over (opengovsg/formsg-private#130)
+  mail_us: MailConfig
+  mail_sg: MailConfig
+  nodemailer_sg_warmup_start_date: string
 
   cookieSettings: SessionOptions['cookie']
   // Consts
@@ -104,11 +107,17 @@ export type Config = {
 
 // Interface
 export interface IProdOnlyVarsSchema {
-  port: number
-  host: string
-  user: string
-  pass: string
+  // TODO #130 Remove references to US SES when SES migration is over (opengovsg/formsg-private#130)
+  port_us: number
+  host_us: string
+  user_us: string
+  pass_us: string
   dbHost: string
+  port_sg: number
+  host_sg: string
+  user_sg: string
+  pass_sg: string
+  nodemailer_sg_warmup_start_date: string
 }
 
 export interface ICompulsoryVarsSchema {

tests/.test-env

@@ -67,6 +67,12 @@ SESSION_SECRET=sandcrawler-138577
 SES_PORT=1025 
 SES_HOST=0.0.0.0
 
+# TODO #130 Remove these when SES migration is over (opengovsg/formsg-private#130)
+SES_PORT_US=1025
+SES_HOST_US=0.0.0.0
+SES_PORT_SG=1025
+SES_HOST_SG=0.0.0.0
+
 SERVICES=s3
 
 IMAGE_S3_BUCKET=local-image-bucket