Heroku给了我503，但我不知道为什么

因此Heroku可以很好地显示我的前端，但是当我打电话给我的后端时，它只返回503，而我对谷歌找到我的问题的答案没有好运。

这是我的服务器

const restify = require('restify');
const mongoose = require('mongoose')
const db = mongoose.connection
const router = require('./routes')
let PORT = process.env.PORT || process.env.VUE_APP_HOST

require('dotenv').config()

const server = restify.createServer({
    name: 'myapp',
    version: '1.0.0'
})

server.use(restify.plugins.acceptParser(server.acceptable))
server.use(restify.plugins.queryParser());
server.use(restify.plugins.bodyParser());
router.applyRoutes(server)
const uri = process.env.SERVER

mongoose.connect(uri, {
        useNewUrlParser: true,
        useUnifiedTopology: true,
        useCreateIndex:true
    },
    () => console.log('Database connected'))

db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function () {
    // we're connected!
    console.log('mongoose is connected')
})

server.get('/*', restify.plugins.serveStatic({
    directory: './dist',
    default: 'index.html',
  }));

server.listen(PORT, function () {
    console.log('%s listening at %s', server.name, server.url);
});

这是我的日志文件

-----> Node.js app detected

-----> Creating runtime environment

       NPM_CONFIG_LOGLEVEL=error
       NODE_ENV=production
       NODE_MODULES_CACHE=true
       NODE_VERBOSE=false

-----> Installing binaries
       engines.node (package.json):  13.8.0
       engines.npm (package.json):   unspecified (use default)

       Resolving node version 13.8.0...
       Downloading and installing node 13.8.0...
       Using default npm version: 6.13.6

-----> Restoring cache
       - node_modules

-----> Installing dependencies
       Installing node modules (package.json + package-lock)
       audited 19449 packages in 12.185s

       46 packages are looking for funding
         run `npm fund` for details

       found 13 vulnerabilities (11 low, 2 moderate)
         run `npm audit fix` to fix them, or `npm audit` for details

-----> Build
       Running build

       > [email protected] build /tmp/build_1b1e8d06246614eaf4f8c73b7396ab26
       > vue-cli-service build


-  Building for production...
        WARNING  Compiled with 2 warnings9:31:34 PM

        warning  

       asset size limit: The following asset(s) exceed the recommended size limit (244 KiB).
       This can impact web performance.
       Assets: 
         css/chunk-vendors.f2de1e82.css (291 KiB)
         js/chunk-vendors.25e54ca6.js (249 KiB)

        warning  

       entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
       Entrypoints:
         app (550 KiB)
             css/chunk-vendors.f2de1e82.css
             js/chunk-vendors.25e54ca6.js
             css/app.83b7036f.css
             js/app.d2d7e1c2.js


         File                                    Size              Gzipped

         dist/js/chunk-vendors.25e54ca6.js       249.22 KiB        83.71 KiB
         dist/js/chunk-322ddd76.30a6d833.js      84.76 KiB         22.35 KiB
         dist/js/chunk-7a6727f2.c0631d11.js      21.09 KiB         6.60 KiB
         dist/js/chunk-fd105068.4e2b7450.js      20.63 KiB         5.84 KiB
         dist/js/chunk-5e9478d9.aa473c10.js      11.85 KiB         3.72 KiB
         dist/js/app.d2d7e1c2.js                 9.00 KiB          3.59 KiB
         dist/js/chunk-ef9ba634.75ba4138.js      4.23 KiB          1.78 KiB
         dist/js/chunk-20b8df38.167c1cfd.js      2.49 KiB          1.09 KiB
         dist/js/chunk-2d0ac3bd.a6df4124.js      2.18 KiB          1.05 KiB
         dist/js/chunk-2d20ec06.bc0797f6.js      1.77 KiB          0.92 KiB
         dist/js/chunk-beee9c80.2f37298d.js      1.37 KiB          0.64 KiB
         dist/js/chunk-2d230542.1693dee0.js      1.23 KiB          0.73 KiB
         dist/css/chunk-vendors.f2de1e82.css     291.44 KiB        32.34 KiB
         dist/css/chunk-fd105068.ee4c284f.css    35.29 KiB         4.49 KiB
         dist/css/chunk-322ddd76.fa9ee5dc.css    24.36 KiB         3.88 KiB
         dist/css/chunk-beee9c80.0670aa22.css    9.98 KiB          1.31 KiB
         dist/css/chunk-5e9478d9.6c52e948.css    8.44 KiB          1.71 KiB
         dist/css/chunk-7a6727f2.e044490b.css    3.71 KiB          1.00 KiB
         dist/css/chunk-20b8df38.c7315fda.css    0.89 KiB          0.35 KiB
         dist/css/app.83b7036f.css               0.03 KiB          0.05 KiB

         Images and other types of assets omitted.

        DONE  Build complete. The dist directory is ready to be deployed.
        INFO  Check out deployment instructions at .html


-----> Caching build
       - node_modules

-----> Pruning devDependencies
       removed 1037 packages and audited 444 packages in 13.024s

       13 packages are looking for funding
         run `npm fund` for details

       found 0 vulnerabilities


-----> Build succeeded!
-----> Discovering process types
       Default types for buildpack -> web
-----> Compressing...
       Done: 50.5M
-----> Launching...
       Released v46
       / deployed to Heroku

我找不到有关如何解决此问题的任何信息。当我在本地运行服务器时，一切都很好，但是Heroku似乎讨厌我。

我去了mongodb地图集页面，并将每个IP地址列入了白名单。然后，我将数据库连接字符串设置为Heroku中的变量。]​​>