Node.js 如何编写一个简单的lambda函数在AmazonS3中上传pdf？

我是node.js的新开发人员，我想在node.js中编写一个小lambda函数，将pdf文件（从硬盘）上传到AmazonS3存储桶

这是我的密码：

// dependencies
var util = require('util');
var fs = require('fs');

exports.handler = function (req, res) {
    var file = req.files.file;
    fs.readFile("‪C:\\Users\\zack\\Downloads\\test.pdf", function (err, data) {
        if (err) throw err; // Something went wrong!
        var s3bucket = new AWS.S3({params: {Bucket: 'myBucket3'}});
        s3bucket.createBucket(function () {
            var params = {
                Key: file.originalFilename, //file.name doesn't exist as a property
                Body: data
            };
            s3bucket.upload(params, function (err, data) {
                // Whether there is an error or not, delete the temp file
                fs.unlink("‪C:\\Users\\zack\\Downloads\\test.pdf", function (err) {
                    if (err) {
                        console.error(err);
                    }
                    console.log('Temp File Delete');
                });

                console.log("PRINT FILE:", file);
                if (err) {
                    console.log('ERROR MSG: ', err);
                    res.status(500).send(err);
                } else {
                    console.log('Successfully uploaded data');
                    res.status(200).end();
                }
            });
        });
    });
};

lambda函数向我显示以下错误消息：

 "errorMessage": "RequestId: 05024c81-f44b-11e6-a45e-57b13036ad96 Process exited before completing request"

还有云手表：

START RequestId: e66a7653-f44b-11e6-8b1a-c511605a533b Version: $LATEST
2017-02-16T13:29:11.133Z    e66a7653-f44b-11e6-8b1a-c511605a533b    TypeError: Cannot read property 'file' of undefined
    at exports.handler (/var/task/invoices3/invoices3.js:17:25)
END RequestId: e66a7653-f44b-11e6-8b1a-c511605a533b
REPORT RequestId: e66a7653-f44b-11e6-8b1a-c511605a533b  Duration: 27.82 ms  Billed Duration: 100 ms     Memory Size: 1024 MB    Max Memory Used: 23 MB  
RequestId: e66a7653-f44b-11e6-8b1a-c511605a533b Process exited before completing request

你能告诉我哪里出了问题吗？？我根本不擅长node.js

提前谢谢你

进程在完成请求之前退出

您收到此消息是因为您从未通知Lambda函数已完成。完成后，您需要调用

context.succeed（）

函数，或者使用较新的

callback（）

方法，并在完成后调用该方法