I am trying to do a fs.read after the promise job is done by using the .then()
Here is how my code looks like
(async () => {
const feed = await parser.parseURL('https://www.nasa.gov/rss/dyn/breaking_news.rss');
console.log(feed.title);
const items = [];
await Promise.all(feed.items.map(async (currentItem) => {
// some code here to create data
items.push(data);
})).then(
items.forEach((element) => {
const file = downloadFile(element.url);
let checksumValue;
try {
fs.readFileSync(file, (_err, data) => {
checksumValue = generateChecksum(data);
console.log(`The checksum is: ${checksumValue}`);
// Delete the downloaded file
deleteFile(file);
});
} catch (error) {
console.error(error);
// expected output: ReferenceError: nonExistentFunction is not defined
// Note - error messages will vary depending on browse
}
})(),
);
})();
But it doesn't operate this piece of code :
fs.readFileSync(file, (_err, data) => {
checksumValue = generateChecksum(data);
console.log(`The checksum is: ${checksumValue}`);
// Delete the downloaded file
deleteFile(file);
});
How should I read the file?
fs.readFileSync is sync, so it doesn't take a callback.
Either use the non-sync version:
fs.readFile(file, (_err, data) => {
checksumValue = generateChecksum(data);
console.log(`The checksum is: ${checksumValue}`);
// Delete the downloaded file
deleteFile(file);
});
or use it as intended:
const data = fs.readFileSync(file);
checksumValue = generateChecksum(data);
console.log(`The checksum is: ${checksumValue}`);
// Delete the downloaded file
deleteFile(file);
I'm currently making use of a node.js plugin called s3-upload-stream to stream very large files to Amazon S3. It uses the multipart API and for the most part it works very well.
However, this module is showing its age and I've already had to make modifications to it (the author has deprecated it as well). Today I ran into another issue with Amazon, and I would really like to take the author's recommendation and start using the official aws-sdk to accomplish my uploads.
BUT.
The official SDK does not seem to support piping to s3.upload(). The nature of s3.upload is that you have to pass the readable stream as an argument to the S3 constructor.
I have roughly 120+ user code modules that do various file processing, and they are agnostic to the final destination of their output. The engine hands them a pipeable writeable output stream, and they pipe to it. I cannot hand them an AWS.S3 object and ask them to call upload() on it without adding code to all the modules. The reason I used s3-upload-stream was because it supported piping.
Is there a way to make aws-sdk s3.upload() something I can pipe the stream to?
Wrap the S3 upload() function with the node.js stream.PassThrough() stream.
Here's an example:
inputStream
.pipe(uploadFromStream(s3));
function uploadFromStream(s3) {
var pass = new stream.PassThrough();
var params = {Bucket: BUCKET, Key: KEY, Body: pass};
s3.upload(params, function(err, data) {
console.log(err, data);
});
return pass;
}
A bit late answer, it might help someone else hopefully. You can return both writeable stream and the promise, so you can get response data when the upload finishes.
const AWS = require('aws-sdk');
const stream = require('stream');
const uploadStream = ({ Bucket, Key }) => {
const s3 = new AWS.S3();
const pass = new stream.PassThrough();
return {
writeStream: pass,
promise: s3.upload({ Bucket, Key, Body: pass }).promise(),
};
}
And you can use the function as follows:
const { writeStream, promise } = uploadStream({Bucket: 'yourbucket', Key: 'yourfile.mp4'});
const readStream = fs.createReadStream('/path/to/yourfile.mp4');
const pipeline = readStream.pipe(writeStream);
Now you can either check promise:
promise.then(() => {
console.log('upload completed successfully');
}).catch((err) => {
console.log('upload failed.', err.message);
});
Or using async/await:
try {
await promise;
console.log('upload completed successfully');
} catch (error) {
console.log('upload failed.', error.message);
}
Or as stream.pipe() returns stream.Writable, the destination (writeStream variable above), allowing for a chain of pipes, we can also use its events:
pipeline.on('close', () => {
console.log('upload successful');
});
pipeline.on('error', (err) => {
console.log('upload failed', err.message)
});
In the accepted answer, the function ends before the upload is complete, and thus, it's incorrect. The code below pipes correctly from a readable stream.
Upload reference
async function uploadReadableStream(stream) {
const params = {Bucket: bucket, Key: key, Body: stream};
return s3.upload(params).promise();
}
async function upload() {
const readable = getSomeReadableStream();
const results = await uploadReadableStream(readable);
console.log('upload complete', results);
}
You can also go a step further and output progress info using ManagedUpload as such:
const manager = s3.upload(params);
manager.on('httpUploadProgress', (progress) => {
console.log('progress', progress) // { loaded: 4915, total: 192915, part: 1, key: 'foo.jpg' }
});
ManagedUpload reference
A list of available events
I think it's worth updating the answer for AWS SDK v3 :).
S3 Client doesn't have upload function anymore and the #aws-sdk/lib-storage package is suggested instead as per https://github.com/aws/aws-sdk-js-v3/blob/main/lib/lib-storage/README.md
Hence the resulting snippet should look like this:
import { S3Client } from '#aws-sdk/client-s3';
import { Upload } from '#aws-sdk/lib-storage';
const stream = require('stream');
...
const client = new S3Client({
credentials: {
accessKeyId: process.env.AWS_ACCESS_KEY_ID,
secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
},
region: process.env.AWS_DEFAULT_REGION,
});
...
async function uploadStream(readableStream) {
const Key = 'filename.pdf';
const Bucket = 'bucket-name';
const passThroughStream = new stream.PassThrough();
let res;
try {
const parallelUploads3 = new Upload({
client,
params: {
Bucket,
Key,
Body: passThroughStream,
ACL:'public-read',
},
queueSize: 4,
partSize: 1024 * 1024 * 5,
leavePartsOnError: false,
});
readableStream.pipe(passThroughStream);
res = await parallelUploads3.done();
} catch (e) {
console.log(e);
}
return res;
}
None of the answers worked for me because I wanted to:
Pipe into s3.upload()
Pipe the result of s3.upload() into another stream
The accepted answer doesn't do the latter. The others rely on the promise api, which is cumbersome to work when working with stream pipes.
This is my modification of the accepted answer.
const s3 = new S3();
function writeToS3({Key, Bucket}) {
const Body = new stream.PassThrough();
s3.upload({
Body,
Key,
Bucket: process.env.adpBucket
})
.on('httpUploadProgress', progress => {
console.log('progress', progress);
})
.send((err, data) => {
if (err) {
Body.destroy(err);
} else {
console.log(`File uploaded and available at ${data.Location}`);
Body.destroy();
}
});
return Body;
}
const pipeline = myReadableStream.pipe(writeToS3({Key, Bucket});
pipeline.on('close', () => {
// upload finished, do something else
})
pipeline.on('error', () => {
// upload wasn't successful. Handle it
})
Type Script solution:
This example uses:
import * as AWS from "aws-sdk";
import * as fsExtra from "fs-extra";
import * as zlib from "zlib";
import * as stream from "stream";
And async function:
public async saveFile(filePath: string, s3Bucket: AWS.S3, key: string, bucketName: string): Promise<boolean> {
const uploadStream = (S3: AWS.S3, Bucket: string, Key: string) => {
const passT = new stream.PassThrough();
return {
writeStream: passT,
promise: S3.upload({ Bucket, Key, Body: passT }).promise(),
};
};
const { writeStream, promise } = uploadStream(s3Bucket, bucketName, key);
fsExtra.createReadStream(filePath).pipe(writeStream); // NOTE: Addition You can compress to zip by .pipe(zlib.createGzip()).pipe(writeStream)
let output = true;
await promise.catch((reason)=> { output = false; console.log(reason);});
return output;
}
Call this method somewhere like:
let result = await saveFileToS3(testFilePath, someS3Bucket, someKey, someBucketName);
The thing here to note in the most accepted answer above is that:
You need to return the pass in the function if you are using pipe like,
fs.createReadStream(<filePath>).pipe(anyUploadFunction())
function anyUploadFunction () {
let pass = new stream.PassThrough();
return pass // <- Returning this pass is important for the stream to understand where it needs to write to.
}
Otherwise it will silently move onto next without throwing an error or will throw an error of TypeError: dest.on is not a function depending upon how you have written the function
Following the other answers and using the latest AWS SDK for Node.js, there's a much cleaner and simpler solution since the s3 upload() function accepts a stream, using await syntax and S3's promise:
var model = await s3Client.upload({
Bucket : bucket,
Key : key,
ContentType : yourContentType,
Body : fs.createReadStream(path-to-file)
}).promise();
For those complaining that the when they use the s3 api upload function and a zero byte file ends up on s3 (#Radar155 and #gabo) - I also had this problem.
Create a second PassThrough stream and just pipe all data from the first to the second and pass the reference to that second to s3. You can do this in a couple of different ways - possibly a dirty way is to listen for the "data" event on the first stream and then write that same data to the second stream - the similarly for the "end" event - just call the end function on the second stream. I've no idea whether this is a bug in the aws api, the version of node or some other issue - but it worked around the issue for me.
Here is how it might look:
var PassThroughStream = require('stream').PassThrough;
var srcStream = new PassThroughStream();
var rstream = fs.createReadStream('Learning/stocktest.json');
var sameStream = rstream.pipe(srcStream);
// interesting note: (srcStream == sameStream) at this point
var destStream = new PassThroughStream();
// call your s3.upload function here - passing in the destStream as the Body parameter
srcStream.on('data', function (chunk) {
destStream.write(chunk);
});
srcStream.on('end', function () {
dataStream.end();
});
If it helps anyone I was able to stream from the client to s3 successfully:
https://gist.github.com/mattlockyer/532291b6194f6d9ca40cb82564db9d2a
The serverside code assumes req is a stream object, in my case it was sent from the client with file info set in the headers.
const fileUploadStream = (req, res) => {
//get "body" args from header
const { id, fn } = JSON.parse(req.get('body'));
const Key = id + '/' + fn; //upload to s3 folder "id" with filename === fn
const params = {
Key,
Bucket: bucketName, //set somewhere
Body: req, //req is a stream
};
s3.upload(params, (err, data) => {
if (err) {
res.send('Error Uploading Data: ' + JSON.stringify(err) + '\n' + JSON.stringify(err.stack));
} else {
res.send(Key);
}
});
};
Yes it breaks convention but if you look at the gist it's much cleaner than anything else I found using multer, busboy etc...
+1 for pragmatism and thanks to #SalehenRahman for his help.
If you're using AWS node SDK v3 there is dedicated module for uploading streams/blobs/buffers.
https://www.npmjs.com/package/#aws-sdk/lib-storage
I'm using KnexJS and had a problem using their streaming API. I finally fixed it, hopefully the following will help someone.
const knexStream = knex.select('*').from('my_table').stream();
const passThroughStream = new stream.PassThrough();
knexStream.on('data', (chunk) => passThroughStream.write(JSON.stringify(chunk) + '\n'));
knexStream.on('end', () => passThroughStream.end());
const uploadResult = await s3
.upload({
Bucket: 'my-bucket',
Key: 'stream-test.txt',
Body: passThroughStream
})
.promise();
Create a new stream.PassThrough() and pipe the input stream to it, then pass the passthrough instance to the body.
Check the following example:
function upload(s3, inputStream) {
const pass = new PassThrough();
inputStream.pipe(pass);
return s3.upload(
{
Bucket: 'bucket name',
Key: 'unique file name',
Body: pass,
},
{
queueSize: 4, // default concurrency
},
).promise()
.then((data) => console.log(data))
.catch((error) => console.error(error));
}
If you know the size of the stream you can use minio-js to upload the stream like this:
s3Client.putObject('my-bucketname', 'my-objectname.ogg', stream, size, 'audio/ogg', function(e) {
if (e) {
return console.log(e)
}
console.log("Successfully uploaded the stream")
})
I am trying to download (meaning create an instance of the file on the server) a .pdf file from a server that returns it to me in binary format, with:
Content-Type = application / octet-stream.
After a bit of online research I came to write:
http.get(url.parse(pdfURL), res => {
let data = [];
console.log(res.statusCode);
res.on('data', chunk => {
data.push(chunk);
}).on('end', () => {
let buffer = Buffer.concat(data);
console.log(buffer.toString('base64'));
fs.open(path, 'w', (e, fd) => {
if (e) throw e;
fs.write(fd, buffer, 0, buffer.length, null, e => {
if (e) throw e;
fs.close(fd, () => console.log('Wrote successfully'));
});
});
});
});
Everything works properly, but when I try to open the generated pdf, it tells me that the file is corrupt and not readable.
Any idea what might have been wrong?
Thanks
Edit:
I noticed that with postman everything works as it should, so I think the way I treat the binary is wrong
Ok, i got it,
I wasn't de-gzipping the response, now works properly
This didn't work for me, tried so many different ways until I found got, an npm library that handles http requests, here's what worked for me:
const stream = require('stream');
const { promisify } = require('util');
const fs = require('fs');
const got = require('got');
const pipeline = promisify(stream.pipeline);
async function downloadImage(url, name) {
await pipeline(
got.stream(url),
fs.createWriteStream(name)
);
}
More info here: https://bleext.com/post/downloading-images-with-nodejs
I want to download a gif from the net and save it in local drive.
So far I have:
1) getFile function that returns the gif as Buffer:
import fs from 'fs'
import https from 'https'
let url = '//some gif url'
const getFile = function(url) {
return new Promise((res, rej) =>{
https.get(url, (resp) => {
let data = [];
resp.on('data', (chunk) => {
data.push(chunk);
});
resp.on('end', () => {
var buffer = Buffer.concat(data);
res(buffer)
});
}).on("error", (err) => {
rej(err);
});
})
}
2) Saving function:
async function save() {
let data = await getFile(url)
fs.writeFile('./test.gif', data, (e, r) => {
console.log(e,r) // null, undefined
})
}
save()
The file is saved and have contents but when i try to open it it says: Could not load image....
I tried to convert the output as utf8 encoding but it gives me the same result.
NOTE: I want to make it work with raw nodejs without 3-party tools or "pipe" to understand the working parts.
I guess the problem is with encoding but i could't figure what exactly it is.
Thanks
I am using ssh2-sftp-client for nodeJS to connect to sftp server and get a file
But I've meet a problem, when are more chunks than one, the data is not received correctly, it loses one character between chunks:
ex.: file on sftp has 'some string from sftp file'
and if it is splitted in chunks, the received data will be like:
first chunk : 'some string f'
second chink: 'om sftp file'
in this example 'r' is lost
const getFile = readable => new Promise((resolve, reject) => {
let file = '';
readable.on('data', (chunk) => { file += chunk; });
readable.on('end', () => resolve(file));
readable.on('error', reject);
});
const readable = await sftp.get(fileName, false);
sftp.get() return NodeJS.ReadableStream
Does someone meet same problem?
Is it more advisable to store chunks as a array and then concat them into a buffer and get the string value on end:
const fs = require('fs');
const getFile = readable => new Promise((resolve, reject) => {
const file = [];
readable.on('data', chunk => file.push(Buffer.from(chunk, 'base64')));
readable.on('end', () => resolve(Buffer.concat(file).toString()));
readable.on('error', reject);
});
const readable = fs.createReadStream('package.json');
getFile(readable).then(file => console.log('file', file));
Runned it locally and getting the content of my file as expected.
After a long research I found the problem, in module sftp-stream, for readable stream highWaterMark is seted to 64*1024, and the bug is that if a chunk has 64*1024 bites then one bite is lost. And I just setted watermark to 64*1024-1 .