node.js on heroku keeps losing image after a while

问题

my Node.js app keeps losing static images(.jpg, .png...) after a while. It doesn't lose any images on my local win10 desktop and even on heroku, my webpack bundle.js is served from the same static route(/pub or /dist) and they work just fine. somehow only the static images, they are served alright for first few minutes when I first uploaded then after a while, it disappears. I am using express.static for static route declaration and multer for file upload. The files used for test were all lowercase .jpg(since I've heard heroku arbitrarily changes all uppercase extensions) so I don't know what's causing the problem.

server code:

const storage = multer.diskStorage({
  destination: (req,file,cb)=>{
    cb(null,'pub/')
  },
  filename: (req,file,cb)=>{
    cb(null,Date.now() + file.originalname)
  }
})
const upload = multer({storage:storage})

//access to static files
app.use('/pub', express.static(pubDir))
app.use('/dist', express.static(dstDir))

app.post('/modwimg',upload.any(),(req,res,next)=>{
//here I connect filename from files array to db
})

then if there's a client request, the server fetches filename from the db and put '/pub/' in front of it. It works just fine on both my local machine and heroku. it's only that images on heroku disappear after a while.

回答1:

The heroku file system is transient. If you want to allow users to upload files to your app, you'll need to use external storage like S3, database blobs, or a hosted service like cloudinary. See this thread for more information: https://www.reddit.com/r/rails/comments/2k9sq4/heroku_any_files_you_upload_will_not_be_saved/

来源：https://stackoverflow.com/questions/49021249/node-js-on-heroku-keeps-losing-image-after-a-while