无法在Heroku服务器上上传图像 [英] Can't upload images on Heroku server

问题描述

上传图片到Heroku服务器，在本地主机上的一切工作很好的问题。但在Heroku上传图片时，看起来一切顺利，但在刷新页面之后，我收到了404（Not Found）的错误消息，因此看起来没有上传。

这里是我的代码

$ $ p $ $ $ $ ），
server = app.listen（process.env.PORT || 5000），
fs = require（'fs-extra'），
im = require（'imagemagick'），
util = require（'util'），
formidable = require（'formidable'）;
$ b app.post（'/ upload'，function（req，res）{
var form = new formidable.IncomingForm（）;


form.parse（req，function（err，fields，files）{
res.writeHead（200，{'content-type'：'text / plain'}）;
res。 write（'received upload：\\\
\\\
'）;
console.log（fields +''+ files）;
res.end（util.inspect（{fields：fields，files：文件}））;
））;

form.on（'end'，function（fields，files）{
var that = this;
//临时存储镜像
var temp_path = that.openedFiles [0] .path;
//上传镜像名称
var file_name = that.openedFiles [0] .name;
var dirpath = __dirname +'/ app';
var opt = {
thumb：{
width：150，$ b $ height：150，
dest：'/ uploads /缩略图/'
}，
原始：{
dest：'/ uploads / original /'
}
};

//获取图片的扩展名
var extension;
（function（type）{
if（type =='image / jpeg'|| type =='image / jpg'）{
extension ='.jpg';
）else if（type =='image / png'）{
extension ='.png';
}
}）（that.openedFiles [0] .type）;
$ b fs.copy（temp_path，dirpath + opt.original.dest + id + extension，function（err）{
if（err）{
console.error（err） ;
} else {
//缩略图
im.crop（{
srcPath：dirpath + opt.original.dest + id +扩展名，
dstPath：dirpath + opt.thumb.dest + id + extension，
width：opt.thumb.width，
height：opt.thumb.height，
质量：1，
gravity：'Center '
}，函数（err，stdout，stderr）{
if（err）{console.log（'Thumbnail is not generated'）}
else {
}
}）;
}
}）;
}）;
}）;

哪里可能有问题？

解决方案

在云环境中，您绝不应该将图像上传到实例本身。总是使用一个像S3这样的中央存储来存储您上传的文件。

在云环境中开发时，请始终记住当前正在运行的框你的代码只能活一段时间（几分钟，几小时）。因此，如果实例出现故障，您将丢失所有上传的文件。

例如，如果您有2个实例，并且您的用户上传图像以安装x 。现在，当第二个用户尝试查看图像，但负载平衡器将请求发送到实例y时，图像未找到，因为该实例中不存在该图像。

为了调试你的脚本，我会添加更多的日志记录。然后在Heroku中，您可以使用：

  heroku日志-t -a appname 
  

观看应用程序的日志。

Got some problem with uploading images to heroku server, on localhost everything work great. But on heroku when I upload image, it looks that all goes well but after refreshing the page I got a error message 404 (Not Found) so it seems that it doesn't uploaded.

Here is my code

var express = require('express'),
    app = express(),
    server = app.listen(process.env.PORT || 5000),
    fs = require('fs-extra'),
    im = require('imagemagick'),
    util = require('util'),
    formidable = require('formidable');

app.post('/upload', function (req, res){
  var form = new formidable.IncomingForm();

  // show respond
  form.parse(req, function(err, fields, files) {
    res.writeHead(200, {'content-type': 'text/plain'});
    res.write('received upload:\n\n');
    console.log(fields + ' ' + files);
    res.end(util.inspect({fields: fields, files: files}));
  });

  form.on('end', function(fields, files) {
    var that = this;
    // temporary storage of image
    var temp_path = that.openedFiles[0].path;
    // uploaded image name
    var file_name = that.openedFiles[0].name;
    var dirpath = __dirname + '/app';
    var opt = {
      thumb : {
        width: 150,
        height: 150,
        dest: '/uploads/thumbnails/'
      },
      original : {
        dest : '/uploads/original/'
      }
    };

    // get extension of image
    var extension;
    (function(type) {
      if (type == 'image/jpeg' || type == 'image/jpg') {
        extension = '.jpg';
      } else if (type == 'image/png') {
        extension = '.png';
      }
    })(that.openedFiles[0].type);

    fs.copy(temp_path, dirpath + opt.original.dest + id + extension, function(err) {
      if (err) {
        console.error(err);
      } else {
        // thumbnails
        im.crop({
          srcPath: dirpath + opt.original.dest + id + extension,
          dstPath: dirpath + opt.thumb.dest + id + extension,
          width: opt.thumb.width,
          height: opt.thumb.height,
          quality: 1,
          gravity: 'Center'
        }, function (err, stdout, stderr){
          if (err) {console.log('Thumbnail is not generated')}
            else {
            }
        });
      }
    });
  });
});

Where could be a problem?

解决方案

In a cloud environment you should never upload images to the instance itself. Always use a central storage like for example S3 to store your uploaded files.

When you develop in a cloud environment you should always keep in mind that the current box you are running your code will only live for a certain amount of time (minutes, hours). So if the instances goes down you'll lose all your uploaded files.

Another problem can occur when you for example have 2 instances and your user uploads an image to instace x. Now when a second user tries to view the image but the load balancer will sent the request to instance y the image is not found because it doesn't exist on that instance.

For debugging your script I would add some more logging. Then in Heroku you could use :

heroku logs -t -a appname

to watch the logs of your application.

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