GraphQL subscription on same server throws error. Connection closed before receiving a handshake response.

[ph55]

Trying to configure GraphQL subscriptions using existing express server.

But seems that there is some kind of conflict.
Error thrown in graphiql console:

WebSocket connection to 'ws://localhost:3000/subscriptions' failed: Connection closed before receiving a handshake response

When using new server. There is no error.

Here the graphQL configuration I've used:
this.setSameServer() - uses nest http server instance.
this.setDifferentServer() - uses new http instance.

import {
  MiddlewareConsumer,
  Module,
  HttpServer,
  Inject,
  NestModule,
  OnModuleDestroy,
} from '@nestjs/common';
import { AppController } from 'app.controller';
import { AppService } from 'app.service';
import { graphqlExpress, graphiqlExpress } from 'apollo-server-express';
import { GraphQLModule, GraphQLFactory } from '@nestjs/graphql';
import { AuthorResolver } from 'author.resolver';
import { SubscriptionServer } from 'subscriptions-transport-ws';
import { execute, subscribe } from 'graphql';
import { createServer } from 'http';
import { HTTP_SERVER_REF } from '@nestjs/core';

@Module({
  imports: [GraphQLModule, AuthorResolver],
  controllers: [AppController],
  providers: [
    {
      provide: 'SUBSCRIPTION_SERVER',
      useFactory: () => {
        const server = createServer();
        return new Promise(resolve => server.listen(88, () => resolve(server)));
      },
    },
    AppService,
  ],
})
export class AppModule implements NestModule, OnModuleDestroy {
  private subscriptionServer: SubscriptionServer;
  private subscriptionPort: number;
  private wsServer: HttpServer;

  constructor(
    private readonly graphQLFactory: GraphQLFactory,
    @Inject(HTTP_SERVER_REF) private readonly httpServerRef: HttpServer,
    @Inject('SUBSCRIPTION_SERVER') private readonly ws: HttpServer,
  ) {
    this.setSameServer();
    //this.setDifferentServer();
  }

  private setSameServer() {
    this.wsServer = this.httpServerRef.getHttpServer();
    this.subscriptionPort = 3000;
  }

  private setDifferentServer() {
    this.wsServer = this.ws;
    this.subscriptionPort = 88;
  }

  public configure(consumer: MiddlewareConsumer) {
    const typeDefs = this.graphQLFactory.mergeTypesByPaths('./**/*.graphql');
    const schema = this.graphQLFactory.createSchema({ typeDefs });

    const route = '/graphql';
    const routeIDE = '/graphiql';
    const routeSubs = '/subscriptions';

    const middlewareIDE = graphiqlExpress({
      endpointURL: route,
      subscriptionsEndpoint:
        'ws://localhost:' + this.subscriptionPort + routeSubs,
    });
    const middleware = graphqlExpress(req => ({
      schema,
      rootValue: req,
      debug: false,
    }));

    consumer.apply(middleware).forRoutes(route);
    consumer.apply(middlewareIDE).forRoutes(routeIDE);

    this.subscriptionServer = new SubscriptionServer(
      {
        execute,
        subscribe,
        schema,
      },
      {
        server: this.wsServer,
        path: routeSubs,
      },
    );
  }

  public onModuleDestroy() {
    this.subscriptionServer.close();
  }
}

Used these issues for help:
#500
nestjs/graphql#6

And full repo if you want to reproduce:
https://github.com/ph55/nest-graphql-subscriptions

[kamilmysliwiec]

Please, use @nestjs/graphql repository to report this issue.

[lock]

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