Implement BullMQ for background job processing

* new REDIS_URL environment variable

apps/server/src/integrations/environment/environment.service.ts

@@ -102,4 +102,11 @@ export class EnvironmentService {
   getPostmarkToken(): string {
     return this.configService.get<string>('POSTMARK_TOKEN');
   }
+
+  getRedisUrl(): string {
+    return this.configService.get<string>(
+      'REDIS_URL',
+      'redis://@127.0.0.1:6379',
+    );
+  }
 }

apps/server/src/integrations/mail/drivers/postmark.driver.ts

@@ -25,6 +25,7 @@ export class PostmarkDriver implements MailDriver {
       this.logger.debug(`Sent mail to ${message.to}`);
     } catch (err) {
       this.logger.warn(`Failed to send mail to ${message.to}: ${err}`);
+      throw err;
     }
   }
 }

apps/server/src/integrations/mail/drivers/smtp.driver.ts

@@ -27,6 +27,7 @@ export class SmtpDriver implements MailDriver {
       this.logger.debug(`Sent mail to ${message.to}`);
     } catch (err) {
       this.logger.warn(`Failed to send mail to ${message.to}: ${err}`);
+      throw err;
     }
   }
 }

apps/server/src/integrations/mail/mail.module.ts

@@ -5,9 +5,12 @@ import {
 } from './providers/mail.provider';
 import { MailModuleOptions } from './interfaces';
 import { MailService } from './mail.service';
+import { EmailProcessor } from './processors/email.processor.';
 
 @Global()
-@Module({})
+@Module({
+  providers: [EmailProcessor],
+})
 export class MailModule {
   static forRootAsync(options: MailModuleOptions): DynamicModule {
     return {

apps/server/src/integrations/mail/mail.service.ts

@@ -3,16 +3,24 @@ import { MAIL_DRIVER_TOKEN } from './mail.constants';
 import { MailDriver } from './drivers/interfaces/mail-driver.interface';
 import { MailMessage } from './interfaces/mail.message';
 import { EnvironmentService } from '../environment/environment.service';
+import { InjectQueue } from '@nestjs/bullmq';
+import { QueueName, QueueJob } from '../queue/constants';
+import { Queue } from 'bullmq';
 
 @Injectable()
 export class MailService {
   constructor(
     @Inject(MAIL_DRIVER_TOKEN) private mailDriver: MailDriver,
     private readonly environmentService: EnvironmentService,
+    @InjectQueue(QueueName.EMAIL_QUEUE) private emailQueue: Queue,
   ) {}
 
-  async sendMail(message: Omit<MailMessage, 'from'>): Promise<void> {
+  async sendEmail(message: Omit<MailMessage, 'from'>): Promise<void> {
     const sender = `${this.environmentService.getMailFromName()} <${this.environmentService.getMailFromAddress()}> `;
     await this.mailDriver.sendMail({ from: sender, ...message });
   }
+
+  async sendToQueue(message: Omit<MailMessage, 'from'>): Promise<void> {
+    await this.emailQueue.add(QueueJob.SEND_EMAIL, message);
+  }
 }

apps/server/src/integrations/mail/processors/email.processor..ts

@@ -0,0 +1,39 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { OnWorkerEvent, Processor, WorkerHost } from '@nestjs/bullmq';
+import { QueueName } from '../../queue/constants';
+import { Job } from 'bullmq';
+import { MailService } from '../mail.service';
+
+@Injectable()
+@Processor(QueueName.EMAIL_QUEUE)
+export class EmailProcessor extends WorkerHost {
+  private readonly logger = new Logger(EmailProcessor.name);
+  constructor(private readonly mailService: MailService) {
+    super();
+  }
+
+  async process(job: Job): Promise<void> {
+    try {
+      await this.mailService.sendEmail(job.data);
+    } catch (err) {
+      throw err;
+    }
+  }
+
+  @OnWorkerEvent('active')
+  onActive(job: Job) {
+    this.logger.debug(`Processing ${job.name} job`);
+  }
+
+  @OnWorkerEvent('failed')
+  onError(job: Job) {
+    this.logger.warn(
+      `Error processing ${job.name} job. Reason: ${job.failedReason}`,
+    );
+  }
+
+  @OnWorkerEvent('completed')
+  onCompleted(job: Job) {
+    this.logger.debug(`Completed ${job.name} job`);
+  }
+}

apps/server/src/integrations/queue/constants/index.ts

@@ -0,0 +1 @@
+export * from './queue.constants';

apps/server/src/integrations/queue/constants/queue.constants.ts

@@ -0,0 +1,7 @@
+export enum QueueName {
+  EMAIL_QUEUE = '{email-queue}',
+}
+
+export enum QueueJob {
+  SEND_EMAIL = 'send-email',
+}

apps/server/src/integrations/queue/queue.module.ts

@@ -0,0 +1,36 @@
+import { Global, Module } from '@nestjs/common';
+import { BullModule } from '@nestjs/bullmq';
+import { EnvironmentService } from '../environment/environment.service';
+import { parseRedisUrl } from '../../helpers';
+import { QueueName } from './constants';
+
+@Global()
+@Module({
+  imports: [
+    BullModule.forRootAsync({
+      useFactory: (environmentService: EnvironmentService) => {
+        const redisConfig = parseRedisUrl(environmentService.getRedisUrl());
+        return {
+          connection: {
+            host: redisConfig.host,
+            port: redisConfig.port,
+            password: redisConfig.password,
+          },
+          defaultJobOptions: {
+            attempts: 3,
+            backoff: {
+              type: 'exponential',
+              delay: 10000,
+            },
+          },
+        };
+      },
+      inject: [EnvironmentService],
+    }),
+    BullModule.registerQueue({
+      name: QueueName.EMAIL_QUEUE,
+    }),
+  ],
+  exports: [BullModule],
+})
+export class QueueModule {}