Develop Reference

express.js: pass an uploaded image to s3

I am trying to pass an image uploaded from a react app through express to a managed s3 bucket. The platform/host I am using creates and manages the s3 bucket and generates upload and access urls. This all works fine (I have tested a generated upload url in postman with an image in a binary body and it worked perfectly).
My problem is passing the image through express. I am using multer to get the image from the form but I am assuming multer is turning that image into some kind of file object and s3 is expecting some sort of blob or stream.
In following code, the image in req.file exists, I get a 200 response from s3 with no errors and when I visit the asset url the url works, but the image itself is missing.
const router = Router();
const upload = multer()
router.post('/', upload.single('file'), async (req, res) => {
console.log(req.file)
const asset = req.file
const assetPath = req.headers['asset-path']
let s3URLs = await getPresignedURLS(assetPath)
const sendAsset = await fetch(
s3URLs.urls[0].upload_url, // the s3 upload url
{
method: 'PUT',
headers: {
"Content-Type": asset.mimetype
},
body: asset,
redirect: 'follow'
}
)
console.log("s3 response", sendAsset)
res.status(200).json({"url": s3URLs.urls[0].access_url });
});
export default router;
I am not sure what to do to convert what multer gives me to something that aws s3 will accept. I am also open to getting rid of multer if there is an easier way to upload binary files to express.

Instead of multer, you can use multiparty to get file data from request object. And to upload file to s3 bucket you can use aws-sdk.
const AWS = require("aws-sdk");
const multiparty = require("multiparty");
/**
* Helper method which takes the request object and returns a promise with a data.
*/
const getDataFromRequest = (req) =>
new Promise(async(resolve, reject) => {
const form = new multiparty.Form();
await form.parse(req, (err, fields, files) => {
if (err) reject(err);
const bucketname = fields.bucketname[0];
const subfoldername = fields.subfoldername[0];
const file = files["file"][0]; // get the file from the returned files object
if (!file) reject("File was not found in form data.");
else resolve({
file,
bucketname,
subfoldername
});
});
});
/**
* Helper method which takes the request object and returns a promise with the AWS S3 object details.
*/
const uploadFileToS3Bucket = (
file,
bucketname,
subfoldername,
options = {}
) => {
const s3 = new AWS.S3();
// turn the file into a buffer for uploading
const buffer = readFileSync(file.path);
var originalname = file.originalFilename;
var attach_split = originalname.split(".");
var name = attach_split[0];
// generate a new random file name
const fileName = name;
// the extension of your file
const extension = extname(file.path);
console.log(`${fileName}${extension}`);
const params = {
Bucket: bucketname, //Bucketname
ACL: "private", //Permission
Key: join(`${subfoldername}/`, `${fileName}${extension}`), // File name you want to save as in S3
Body: buffer, // Content of file
};
// return a promise
return new Promise((resolve, reject) => {
return s3.upload(params, (err, result) => {
if (err) reject(err);
else resolve(result); // return the values of the successful AWS S3 request
});
});
};
router.post('/', upload.single('file'), async(req, res) => {
try {
// extract the file from the request object
const {
file,
bucketname,
subfoldername
} = await getDataFromRequest(req);
// Upload File to specified bucket
const {
Location,
ETag,
Bucket,
Key
} = await uploadFileToS3Bucket(
file,
bucketname,
subfoldername
);
let response = {};
res["Location"] = Location;
response["ETag"] = ETag;
response["Bucket"] = Bucket;
response["Key"] = Key;
res.status(200).json(response);
} catch (error) {
throw error;
}
});
Request body will be form data with following fields
bucketname:
subfoldername:
file: FileData

For anyone that ever stumbles across this question the solution was to create an custom multer storage engine. Inside the engine you get access to the file with a stream property that s3 accepted (with the correct headers).

s3 isn't uploading file and getting error of SignatureDoesNotMatch

I'm trying to add images to my s3 bucket in aws, but it doesn't seem to work. I get the error of SignatureDoesNotMatch
Here's how I'm uploading the file/image:
FrontEnd
const file = e.target.files[0];
const fileParts = file.name.split('.');
const fileName = fileParts[0];
const fileType = fileParts[1];
const response = axios.post('api/aws/sign_s3', { fileName, fileType );
Backend
router.post('/sign_s3', async (req, res) => {
aws.config.update({
accessKeyId: config.aws.accessKey,
secretAccessKey: config.aws.secretKey,
region: 'us-west-1'
});
const s3 = new aws.S3(); // Create a new instance of S3
const fileName = req.body.fileName;
const fileType = req.body.fileType;
const s3Params = {
Bucket: config.aws.bucketName,
Key: fileName,
Expires: 500,
ContentType: fileType,
ACL: 'public-read'
};
s3.getSignedUrl('putObject', s3Params, (err, data) => {
if (err) return res.send(err);
const returnData = {
signedRequest: data,
url: `https://sim-to-do.s3.amazonaws.com/${fileName}`
};
res.json({ success: true, responseData: returnData });
});
});
I get two urls. When I go to the first one, I get the following error code:
SignatureDoesNotMatch
Error Message
The request signature we calculated does not match the signature you provided. Check your key and signing method.
What am I doing wrong? What's the correct way of uploading a file to aws s3?

I was able to fix this issue after removing the Content-Type from the headers.

If you get "Signature does not match", it's highly likely you used a wrong secret access key. Can you double-check access key and secret access key to make sure they're correct?
from awendt answer

direct upload string from browser to s3 without local file

I am using javascript, node.js and aws sdk. There are many examples about uploading existing files to S3 directly with signed URL, but now I am trying to upload strings and create a file in S3, without any local saved files. Any suggestion, please?

Please follow the example here
http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property
Convert your string to buffer and pass it. It should work.

Have not tried amazon-web-services, amazon-s3 or aws-sdk, though if you are able to upload File or FormData objects you can create either or both at JavaScript and upload the object.
// create a `File` object
const file = new File(["abc"], "file.txt", {type:"text/plain"});
// create a `Blob` object
// will be converted to a `File` object when passed to `FormData`
const blob = new Blob(["abc"], {type:"text/plain"});
const fd = new FormData();
fd.append("file", blob, "file.txt");

You could try something like this:
var fs = require('fs');
exports.upload = function (req, res) {
var file = req.files.file;
fs.readFile(file.path, function (err, data) {
if (err) throw err; // Something went wrong!
var s3bucket = new AWS.S3({params: {Bucket: 'mybucketname'}});
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(file.path, 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();
}
});
});
});
};

S3: Allow download of files for those who have some token

Is it possible to only allow download from Amazon's S3 for anyone who have some token and a link to some file in my bucket?
This token, for example, can be generated by my upload backend server, and appended to the uploaded file.
What possibilities do I have here?
Edit
When I said download from S3, I mean directly from S3 not through my server, only upload happens through server

You can generate presigned URLs using minio-py like this:
from minio import Minio
client = Minio('s3.amazonaws.com',
access_key='YOUR-ACCESSKEYID',
secret_key='YOUR-SECRETACCESSKEY')
downloadURL = client.presigned_get_object('mybucket', 'myobject')
You can use downloadURL on browser to download files directly from S3.

Of course it is possible, just warp the access with some authentication from your end
var backendTokenAuthenticator = require('/auth')
app.get('/download/:file',function(req, res){
if(req.query.token && req.params.file){
backendTokenAuthenticator(req.query.token,req.params.file,function(err,isAuth){
if(err){
res.status(500).end()
}else if(!isAuth){
res.status(403).end('permission denied')
}else{
var s3 = new AWS.S3();
s3.getObject({
Bucket: "myBucket",
Key: req.params.file
},
function (error, data) {
if (error) {
console.log("Failed to retrieve an object: " + error);
res.status(404).end('File not found');
} else {
res.setHeader('Content-Length', data.ContentLength);
res.setHeader('Content-Type', 'application/octet-stream');
res.end(data.Body)
}
});
}
})
}else{
res.status(403).end('token must be supplied')
}
});

Upload a binary file to S3 using AWS SDK for Node.js

Update: For future reference, Amazon have now updated the documentation from what was there at time of asking. As per #Loren Segal's comment below:-
We've corrected the docs in the latest preview release to document this parameter properly. Sorry about the mixup!
I'm trying out the developer preview of the AWS SDK for Node.Js and want to upload a zipped tarball to S3 using putObject.
According to the documentation, the Body parameter should be...
Body - (Base64 Encoded Data)
...therefore, I'm trying out the following code...
var AWS = require('aws-sdk'),
fs = require('fs');
// For dev purposes only
AWS.config.update({ accessKeyId: 'key', secretAccessKey: 'secret' });
// Read in the file, convert it to base64, store to S3
fs.readFile('myarchive.tgz', function (err, data) {
if (err) { throw err; }
var base64data = new Buffer(data, 'binary').toString('base64');
var s3 = new AWS.S3();
s3.client.putObject({
Bucket: 'mybucketname',
Key: 'myarchive.tgz',
Body: base64data
}).done(function (resp) {
console.log('Successfully uploaded package.');
});
});
Whilst I can then see the file in S3, if I download it and attempt to decompress it I get an error that the file is corrupted. Therefore it seems that my method for 'base64 encoded data' is off.
Can someone please help me to upload a binary file using putObject?

You don't need to convert the buffer to a base64 string. Just set body to data and it will work.

Here is a way to send a file using streams, which might be necessary for large files and will generally reduce memory overhead:
var AWS = require('aws-sdk'),
fs = require('fs');
// For dev purposes only
AWS.config.update({ accessKeyId: 'key', secretAccessKey: 'secret' });
// Read in the file, convert it to base64, store to S3
var fileStream = fs.createReadStream('myarchive.tgz');
fileStream.on('error', function (err) {
if (err) { throw err; }
});
fileStream.on('open', function () {
var s3 = new AWS.S3();
s3.putObject({
Bucket: 'mybucketname',
Key: 'myarchive.tgz',
Body: fileStream
}, function (err) {
if (err) { throw err; }
});
});

I was able to upload my binary file this way.
var fileStream = fs.createReadStream("F:/directory/fileName.ext");
var putParams = {
Bucket: s3bucket,
Key: s3key,
Body: fileStream
};
s3.putObject(putParams, function(putErr, putData){
if(putErr){
console.error(putErr);
} else {
console.log(putData);
}
});