Graphql Gateway for @gapi applications

gateway.ts

import {
  Module,
  CoreModule,
  Bootstrap,
  ON_REQUEST_HANDLER,
  GRAPHQL_PLUGIN_CONFIG,
  Container
} from '@gapi/core';
import {
  MicroserviceModule,
  AFTER_MIDDLEWARE,
  BEFORE_MIDDLEWARE,
  MiddlewareOptions,
  ProxyService
} from '@rxdi/graph-gateway';
import { ResponseToolkit } from 'hapi';
import { promisify } from 'util';
import { load, safeLoad } from 'js-yaml';
import { readFile, readFileSync, stat, statSync } from 'fs';

const fileName = './gateway.yml';
let temp = statSync(fileName).mtime.toISOString();

async function loadYml() {
  return load(await promisify(readFile)(fileName, { encoding: 'utf-8' }));
}
function safeLoadYml() {
  return safeLoad(readFileSync(fileName, { encoding: 'utf-8' }));
}

@Module({
  providers: [
    {
      provide: ON_REQUEST_HANDLER,
      deps: [GRAPHQL_PLUGIN_CONFIG],
      useFactory: (config: GRAPHQL_PLUGIN_CONFIG) => async (
        next,
        request: Request,
        h: ResponseToolkit,
        err: Error
      ) => {
        config.graphqlOptions.context = config.graphqlOptions.context || {};
        config.graphqlOptions.context['headers'] = request.headers;
        const stats = await promisify(stat)(fileName);
        if (new Date(temp).toISOString() !== stats.mtime.toISOString()) {
          config.graphqlOptions.schema = await Container.get(
            ProxyService
          ).getSchemaIntrospection((await loadYml()).services);
          temp = stats.mtime.toISOString();
          console.log('Configuration has changed...');
        }
        return next();
      }
    },
    {
      provide: BEFORE_MIDDLEWARE,
      useFactory: () => (options: MiddlewareOptions) => {
        return options;
      }
    },
    {
      provide: AFTER_MIDDLEWARE,
      useFactory: () => (res, options: MiddlewareOptions) => {
        if (res.statusCode && res.statusCode !== 200) {
          throw new Error('Unauthorized');
        }
        return res;
      }
    }
  ],
  imports: [
    MicroserviceModule.forRoot(safeLoadYml().services),
    CoreModule.forRoot({
      server: {
        hapi: {
          port: 9003
        }
      },
      graphql: {
        path: '/graphql',
        openBrowser: false,
        initQuery: false,
        graphiQlPlayground: true,
        graphiQlPath: '/graphiql',
        watcherPort: 8999,
        graphqlOptions: {
          tracing: true,
          schema: null
        }
      }
    })
  ]
})
export class AppModule {}

Bootstrap(AppModule).subscribe(() => console.log('Started'));