Cannot inject SummarizationService into Temporal Worker activity

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Hello,

I have a monorepo project with multiple NestJS apps, and I’m using nestjs-temporal-core. I have two services:

  1. API Service

  2. Worker Service

I created a shared activity, SummarizationService, that I would like to use in both the API and Worker services.

Summarization Module

import { Module } from '@nestjs/common';
import { LlmModule } from '@corolair/libs/services/shared/llm/llm.module';
import { LLMMonitoring } from '@corolair/libs/services/shared/llm/monitoring/monitoring.module';
import { SummarizationService } from './summarization.service';

@Module({
  imports: [LlmModule, LLMMonitoring],
  providers: [SummarizationService],
  exports: [SummarizationService],
})
export class SummarizationModule {}

Summarization Service

import { Injectable } from '@nestjs/common';

@Injectable()
export class SummarizationService {
  constructor(
    private readonly azureFoundryService: AzureFoundryService,
    private readonly contextService: ContextService,
    private readonly langfuseService: LangfuseService
  ) {}

  async createSummary(transcript: string) {
    // implementation...
  }
}
  • Injecting this service into my API service works fine.

Worker Module

import { Module } from '@nestjs/common';
import { ConfigModule, ConfigService } from '@nestjs/config';
import { TemporalModule } from 'nestjs-temporal-core';
import path from 'path';
import { WorkerTaskQueue } from '@corolair/libs/shared/enums';

import { SummarizationModule } from '@corolair/libs/services/shared/summarization/summarization.module';
import { DocumentWorkerService } from './document-worker.service';
import { NodeWorkerService } from './node-worker.service';

@Module({
  imports: [
    ConfigModule,
    SummarizationModule,
    TemporalModule.registerAsync({
      imports: [ConfigModule],
      inject: [ConfigService],
      useFactory: (configService: ConfigService) => ({
        connection: {
          address: configService.get('TEMPORAL_ADDRESS', 'localhost:7233'),
          namespace: configService.get('TEMPORAL_NAMESPACE', 'default'),
        },
        enableLogger: true,
        logLevel: 'info',
        taskQueue: WorkerTaskQueue.NODE_WORKER,
        worker: {
          activityClasses: [DocumentWorkerService],
          autoStart: true,
          workflowsPath: path.resolve(
            __dirname,
            '../../../libs/services/shared/workflows/src/index.ts'
          ),
        },
      }),
    }),
  ],
  providers: [NodeWorkerService, DocumentWorkerService],
})
export class NodeWorkerModule {}

Worker Activity

import { Injectable } from '@nestjs/common';
import { Activity, ActivityMethod } from 'nestjs-temporal-core';
import { SummarizationService } from '@corolair/libs/services/shared/summarization/summarization.service';

@Injectable()
@Activity()
export class DocumentWorkerService {
  constructor(private readonly summarizationService: SummarizationService) {
    console.log('SummarizationService injected?', !!summarizationService);
  }

  @ActivityMethod()
  async summarizeDocument(documentId: string): Promise<string> {
    console.log('summarizeDocument', documentId);
    return this.summarizationService.createSummary("...long text...");
  }
}

Issue

When I run the workflow, I get the following error:

cause: [ActivityFailure: Activity task failed] {
  cause: TypeError: Cannot read properties of undefined (reading 'createSummary')
}

This indicates that summarizationService is undefined in the worker activity.

What I think is happening

  • In nestjs-temporal-core, when you use activityClasses: [DocumentWorkerService], the library instantiates the class itself, bypassing NestJS DI.

  • As a result, the SummarizationService constructor injection does not work, and the activity cannot access it.

I’d like guidance on the best way to use a NestJS service inside a Temporal worker activity so that:

  1. The worker can run automatically.

  2. The activity has access to the Nest-managed SummarizationService.