Serving files stored in S3 in express/nodejs app

Question

I have app where user's photos are private. I store the photos(thumbnails also) in AWS s3. There is a page in the site where user can view his photos(i.e thumbnails). Now my problem is how do I serve these files. Some options that I have evaluated are:

• Serving files from CloudFront(or AWS) using signed url generation. But the problem is every time the user refreshes the page I have to create so many signed urls again and load it. So therefore I wont be able to cache the Images in the browser which would have been a good choice. Is there anyway to do still in javascript? I cant have the validity of those urls for longer due to security issues. And secondly within that time frame if someone got hold of that url he can view the file without running through authentication from the app.
• Other option is to serve the file from my express app itself after streaming it from S3 servers. This allows me to have http cache headers, therefore enable browser caching. It also makes sure no one can view a file without being authenticated. Ideally I would like to stream the file and a I am hosting using NGINX proxy relay the other side streaming to NGINX. But as i see that can only be possible if the file exist in the same system's files. But here I have to stream it and return when i get the stream is complete. Don't want to store the files locally.

I am not able to evaluate which of the two options would be a better choice?? I want to redirect as much work as possible to S3 or cloudfront but even using singed urls also makes the request first to my servers. I also want caching features.

So what would be ideal way to do? with the answers for the particular questions pertaining to those methods?

Answer 1

i would just stream it from S3. it's very easy, and signed URLs are much more difficult. just make sure you set the content-type and content-length headers when you upload the images to S3.

var aws = require('knox').createClient({
  key: '',
  secret: '',
  bucket: ''
})

app.get('/image/:id', function (req, res, next) {
  if (!req.user.is.authenticated) {
    var err = new Error()
    err.status = 403
    next(err)
    return
  }

  aws.get('/image/' + req.params.id)
  .on('error', next)
  .on('response', function (resp) {
    if (resp.statusCode !== 200) {
      var err = new Error()
      err.status = 404
      next(err)
      return
    }

    res.setHeader('Content-Length', resp.headers['content-length'])
    res.setHeader('Content-Type', resp.headers['content-type'])

    // cache-control?
    // etag?
    // last-modified?
    // expires?

    if (req.fresh) {
      res.statusCode = 304
      res.end()
      return
    }

    if (req.method === 'HEAD') {
      res.statusCode = 200
      res.end()
      return
    }

    resp.pipe(res)
  })
})