问如何异步获取Express应用配置？

EN

import { APIGatewayProxyHandler } from 'aws-lambda'
import 'source-map-support/register'
import serverless from 'serverless-http'
import express from 'express'
import bodyParser from 'body-parser'
import { ExpressOIDC } from '@okta/oidc-middleware'
import session from 'express-session'

const jsonParser = bodyParser.json()

// Retrieve stuff from SSM
const ssmConfig = async() => { ... }

const buildApp(ssmConfig) = (ssmConfig: Record<string, string>) => {
  const app = express()
  app.engine('pug', require('pug').__express)
  app.use(express.static('static'))

  const oidc = new ExpressOIDC({
    issuer: ssmConfig.ISSUER, // `https://${oktaDomain}/oauth2/default`
    client_id: process.env.CLIENT_ID, // Stored in SSM
    client_secret: process.env.CLIENT_SECRET, // Stored in SSM
    appBaseUrl: process.env.APP_BASE_URL, // `https://${apiGatewayId}.execute-api.${AWS::Region}.amazonaws.com/prod`
    scope: 'openid profile'
  })

  app.use(session({
    secret: process.env.SESSION_SECRET!, // Stored in SSM
    resave: true,
    saveUninitialized: false
  }))

  app.use(oidc.router)

  app.set('view engine', 'pug')
  app.set('views', './views')

  app.get('/', oidc.ensureAuthenticated(), async (_req, res) => res.render('index'))

  app.get('/status/:taskId', oidc.ensureAuthenticated(), async (req, res) => { ... })

  app.post('/doPost', oidc.ensureAuthenticated(), jsonParser, async (req, res) => { ... }) 

  return app
}

export const main: APIGatewayProxyHandler = async (event, context) => { 
    ssmConfig = await getSsmConfig(); // this would handle retrieving stuff from SSM
    const app = buildApp(ssmConfig); // build the app w/ config from ssm
    const handle = serverless(app);
    return handle(event, context); // I might need to add an "as <something or other>" to make TypeScript happy
}