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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).

How do I recover from failure when uploading multiple files via my server to S3?

New to NodeJS and S3, I wrote the following exploratory code to upload files to S3 via my NodeJS server without saving the file to disk or memory:
var express = require('express');
var Busboy = require('busboy');
var S3 = require('../utils/s3Util');
var router = express.Router(); // mounted at /uploads
router.post("/", function (req, res, next) {
let bb = new Busboy({ headers: req.headers });
const uploads = [];
bb.on('file', (fieldname, stream, filename, encoding, mimeType) => {
console.log(`Uploaded fieldname: ${fieldname}; filename: ${filename}, mimeType: ${mimeType}`);
uploads.push(S3.svc.upload({ Bucket: 'my-test-bucket', Key: filename, Body: stream }).promise());
});
bb.on('finish', () => {
console.log("# of promises:", uploads.length);
Promise.all(uploads).then(retVals => {
for (let i = 0; retVals && i < retVals.length; i++) {
console.log(`File ${i + 1}::`, retVals[i]);
}
res.end();
}).catch(err => {
console.log("Error::", err);
res.status(500).send(`${err.name}: ${err.message}`);
});
});
req.pipe(bb);
});
module.exports = router;
In the general failure case, how do I handle the scenario where the upload of 1 or more of x files being uploaded fails? Some uploads would have succeeded, some would have failed. However, in the catch clause I wouldn't know which ones have failed...
It would be good to be able to make this upload process somewhat transactional (i.e., either all uploads succeed, or none do). When errors happen, ideally I would be able to "rollback" the subset of successful uploads.

You could do it like this:
Push an object into uploads, with the data you need to retry, so:
uploads.push({
fieldname,
filename,
mimeType,
uploaded: S3.svc.upload({ Bucket: 'my-test-bucket', Key: filename, Body: stream })
.promise()
.then(() => true)
.catch(() => false)
});
...
const failed = await
(Promise.all(uploads.map(async upload => ({...upload, uploaded: await upload.uploaded})))).then(u => u.filter(upload => !upload.uploaded))
const failedFiles = failed.join(', ')
console.log(`The following files failed to upload: ${failedFiles}`);
You need to make your event handlers async to use await inside them, so, for example:
bb.on('file', async (fieldname, stream, filename, encoding, mimeType) => {

I finally went with the following code, which is an expansion of #JoshWulf's answer:
function handleUpload(req, res, bucket, key) {
let bb = new Busboy({ headers: req.headers });
const uploads = [];
bb.on('file', (fieldname, stream, filename, encoding, mimeType) => {
console.log(`Uploaded fieldname: ${fieldname}; filename: ${filename}, mimeType: ${mimeType}`);
const params = { Bucket: bucket, Key: key, Body: stream, ContentType: mimeType };
uploads.push({ filename, result: S3.svc.upload(params).promise().then(data => data).catch(err => err) });
});
bb.on('finish', async () => {
const results = await Promise.all(uploads.map(async (upload) => ({ ...upload, result: await upload.result })));
// handle success/failure with their respective objects
});
req.pipe(bb);
}
The difference here from #Josh Wulf's answer is that in my upload promise I am returning the returned data object (if successful) and the returned error object (in case of failure) as-is. This then enables me to later use them as I need.

Having problems with busboy and not finding Content-Type

I'm having hard times with this package of busboy in some app I'm trying to build wanting to upload images from/to my firebase...
Already tried to look at some of your possible solutions with the same problems but perhaps different code and it didn't work.
May I share mine, so you might give me an idea about what is going wrong?
Here the lines:
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp()
const path = require('path');
const os = require('os');
const cors = require('cors')({ origin: true });
const BusBoy = require('busboy')
const fs = require('fs');
const gcConfig = {
projectId: 'meeting-scheduler-9cee1',
keyFilename: "meeting-scheduler-9cee1-firebase-adminsdk-3unr4-09df5fe69a.json"
}
const { Storage } = require("#google-cloud/storage");
exports.upLoadFile = functions.https.onRequest((request, response) => {
cors(request, response,() => {
const busBoy = new BusBoy({ headers: request.headers});
let uploadData = null;
if (request.method !== "POST") {
return response.status(500).json({
message: 'Not Allowed!!'
})
}
// if (!request.headers['Content-Type']){
// return next(new Error('Bad request'));
// }
// else
// next();
busBoy.on('file', (fieldname, file, filename, encoding, mimetype) => {
const filepath = path.join(os.tmpdir(), filename);
uploadData = { file: filepath, type: mimetype };
file.pipe(fs.createWriteStream(filepath));
});
busBoy.on('finish', () => {
const bucket = gcs.bucket('meeting-scheduler-9cee1.appspot.com');
bucket
.upload(uploadData.file, {
uploadType: 'media',
metadata: {
metadata: {
contentType: uploadData.type
}
}
})
.then(() => {
response.status(200).json({
message: 'It Works!'
});
})
.catch(err => {
response.status(500).json({
error: err
})
})
});
busBoy.end(request.rawBody);
});
});
Any time I fire the function in my firebase de error is the same,I'm sharing it too:
Error: Missing Content-Type
at new Busboy (/srv/node_modules/busboy/lib/main.js:23:11)
at cors (/srv/index.js:58:24)
at cors (/srv/node_modules/cors/lib/index.js:188:7)
at /srv/node_modules/cors/lib/index.js:224:17
at originCallback (/srv/node_modules/cors/lib/index.js:214:15)
at /srv/node_modules/cors/lib/index.js:219:13
at optionsCallback (/srv/node_modules/cors/lib/index.js:199:9)
at corsMiddleware (/srv/node_modules/cors/lib/index.js:204:7)
at exports.upLoadFile.functions.https.onRequest (/srv/index.js:57:5)
at cloudFunction (/srv/node_modules/firebase-functions/lib/providers/https.js:49:9)

Ran into this myself. Turns out, main.js in the busboy module checks for content-type instead of Content-Type, and thus does not find the header. Confirmed this was the issue by fixing the casing in main.js (which isn't a feasible solution in most cases), after which the constructor call worked on my request, as expected.
Apparently this was brought up before, but the issue was closed (link).

For anyone using postman and encounters this issue: I didn't realize the file postman was referencing no longer existed, thus content-type didn't exist, but postman never complained. I switched to a valid file and it worked.

Busboy Save Stream For Use Later

I'm trying to use busboy to allow clients to upload files to my Express web server.
I have the following middleware function I'm running for Express.
module.exports = (req, res, next) => {
req.files = {};
let busboy;
try {
busboy = new Busboy({
headers: req.headers
});
} catch (e) {
return next();
}
busboy.on("file", (fieldname, file, filename, encoding, mimetype) => {
req.files[fieldname] = {
file,
filename,
encoding,
mimetype
};
// Need to call `file.resume` to consume the stream somehow (https://stackoverflow.com/a/24588458/894067)
file.resume();
});
busboy.on("finish", next);
req.pipe(busboy);
};
As you can see, I had to add file.resume(); so that the "finish" event would be triggered, and call the next function for the middleware (https://stackoverflow.com/a/24588458/894067).
The problem is, later on, when I want to consume the stream, it says readable: false. So I'm assuming the file.resume(); discards the stream and doesn't allow it to be used in the future.
I basically want to get all the uploaded files and information associated with those files, store them on the req.files object, then consume the streams later, or not consume them if I don't want to use it. That way they remain streams and don't take up much memory, until I'm ready to consume the stream and actually do something with it (or choose to discard it).
What can I use in place of file.resume(); to ensure that the "finish" event get triggers, while allowing me to use the stream later on in the lifecycle of the request (the actual app.post routes, instead of middleware)?
The client might also upload multiple files. So I need any solution to handle multiple files.

Would it make any sense to pipe the input stream into a PassThrough stream, like this?
const Busboy = require('busboy')
const { PassThrough } = require('stream')
const multipart = (req, res, next) => {
req.files = new Map()
req.fields = new Map()
const busboy = new Busboy({ headers: req.headers })
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
const stream = new PassThrough()
file.pipe(stream)
req.files.set(fieldname, { stream, filename, encoding, mimetype })
})
busboy.on(
'field',
(fieldname, val, fieldnameTruncated, valTruncated, encoding, mimetype) => {
req.fields.set(fieldname, { val, encoding, mimetype })
}
)
busboy.on('error', (error) => {
next(error)
})
busboy.on('finish', () => {
next()
})
busboy.end(req.rawBody)
}

If you want to handle multiple files in a single request, the procedure is a bit tricky.
Busboy goes through a single stream and fires events whenever files arrive (in sequence). You cannot get separate streams for all files at the same time with Busboy. This is not a limitation from the library, this is how HTTP works.
Your best option would be to store all files in a temporary storage, and keep information for the next middlewares with res.locals :
const Busboy = require('busboy');
const path = require('path');
const fs = require('fs');
module.exports = (req, res, next) => {
res.locals.files = {};
// You need to ensure the directory exists
res.locals.someTemporaryDirectory = '/some/temp/dir/with/randomString/in/it';
let busboy;
try {
busboy = new Busboy({
headers: req.headers
});
} catch (e) {
return next(e);
}
busboy.on("file", (fieldname, file, filename, encoding, mimetype) => {
res.locals.files[fieldname + '_' + filename] = {
filename,
encoding,
mimetype
};
// I skipped error handling for the sake of simplicity. Cleanup phase will be required as well
const tempFilePath = path.join(res.locals.someTemporaryDirectory, fieldname + '_' + filename);
file.pipe(fs.createWriteStream(tempFilePath));
});
busboy.on("finish", next);
req.pipe(busboy);
};
The next middleware shall use res.locals.someTemporaryDirectory and res.locals.files to mind their businesses (that will require a clean-up phase).
This solution may seem sub-optimal, but HTTP is like it is. You may want to issue a separate HTTP request for each file instead, but I would not recommend it as you would encounter a bunch of other issues (such as synchronization of all requests + memory management).
Whatever the solution is, it requires to get your hands dirty.

How to perform an HTTP file upload using express on Cloud Functions for Firebase (multer, busboy)

I am trying to upload a file to Cloud Functions, using Express to handle requests there, but i am not succeeding. I created a version that works locally:
serverside js
const express = require('express');
const cors = require('cors');
const fileUpload = require('express-fileupload');
const app = express();
app.use(fileUpload());
app.use(cors());
app.post('/upload', (req, res) => {
res.send('files: ' + Object.keys(req.files).join(', '));
});
clientside js
const formData = new FormData();
Array.from(this.$refs.fileSelect.files).forEach((file, index) => {
formData.append('sample' + index, file, 'sample');
});
axios.post(
url,
formData,
{
headers: { 'Content-Type': 'multipart/form-data' },
}
);
This exact same code seems to break when deployed to Cloud Functions, where req.files is undefined. Does anyone have any idea what is happening here?
EDIT
I also had a go at using multer, which worked fine locally, but once uploaded to Cloud Functions, this got me an empty array (same clientside code):
const app = express();
const upload = multer();
app.use(cors());
app.post('/upload', upload.any(), (req, res) => {
res.send(JSON.stringify(req.files));
});

There was indeed a breaking change in the Cloud Functions setup that triggered this issue. It has to do with the way the middleware works that gets applied to all Express apps (including the default app) used to serve HTTPS functions. Basically, Cloud Functions will parse the body of the request and decide what to do with it, leaving the raw contents of the body in a Buffer in req.rawBody. You can use this to directly parse your multipart content, but you can't do it with middleware (like multer).
Instead, you can use a module called busboy to deal with the raw body content directly. It can accept the rawBody buffer and will call you back with the files it found. Here is some sample code that will iterate all the uploaded content, save them as files, then delete them. You'll obviously want to do something more useful.
const path = require('path');
const os = require('os');
const fs = require('fs');
const Busboy = require('busboy');
exports.upload = functions.https.onRequest((req, res) => {
if (req.method === 'POST') {
const busboy = new Busboy({ headers: req.headers });
// This object will accumulate all the uploaded files, keyed by their name
const uploads = {}
// This callback will be invoked for each file uploaded
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
console.log(`File [${fieldname}] filename: ${filename}, encoding: ${encoding}, mimetype: ${mimetype}`);
// Note that os.tmpdir() is an in-memory file system, so should only
// be used for files small enough to fit in memory.
const filepath = path.join(os.tmpdir(), fieldname);
uploads[fieldname] = { file: filepath }
console.log(`Saving '${fieldname}' to ${filepath}`);
file.pipe(fs.createWriteStream(filepath));
});
// This callback will be invoked after all uploaded files are saved.
busboy.on('finish', () => {
for (const name in uploads) {
const upload = uploads[name];
const file = upload.file;
res.write(`${file}\n`);
fs.unlinkSync(file);
}
res.end();
});
// The raw bytes of the upload will be in req.rawBody. Send it to busboy, and get
// a callback when it's finished.
busboy.end(req.rawBody);
} else {
// Client error - only support POST
res.status(405).end();
}
})
Bear in mind that files saved to temp space occupy memory, so their sizes should be limited to a total of 10MB. For larger files, you should upload those to Cloud Storage and process them with a storage trigger.
Also bear in mind that the default selection of middleware added by Cloud Functions is not currently added to the local emulator via firebase serve. So this sample will not work (rawBody won't be available) in that case.
The team is working on updating the documentation to be more clear about what all happens during HTTPS requests that's different than a standard Express app.

Thanks to the answers above I've built a npm module for this (github)
It works with google cloud functions, just install it (npm install --save express-multipart-file-parser) and use it like this:
const fileMiddleware = require('express-multipart-file-parser')
...
app.use(fileMiddleware)
...
app.post('/file', (req, res) => {
const {
fieldname,
filename,
encoding,
mimetype,
buffer,
} = req.files[0]
...
})

I was able to combine both Brian's and Doug's response. Here's my middleware that end's up mimicking the req.files in multer so no breaking changes to the rest of your code.
module.exports = (path, app) => {
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))
app.use((req, res, next) => {
if(req.rawBody === undefined && req.method === 'POST' && req.headers['content-type'].startsWith('multipart/form-data')){
getRawBody(req, {
length: req.headers['content-length'],
limit: '10mb',
encoding: contentType.parse(req).parameters.charset
}, function(err, string){
if (err) return next(err)
req.rawBody = string
next()
})
} else {
next()
}
})
app.use((req, res, next) => {
if (req.method === 'POST' && req.headers['content-type'].startsWith('multipart/form-data')) {
const busboy = new Busboy({ headers: req.headers })
let fileBuffer = new Buffer('')
req.files = {
file: []
}
busboy.on('field', (fieldname, value) => {
req.body[fieldname] = value
})
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
file.on('data', (data) => {
fileBuffer = Buffer.concat([fileBuffer, data])
})
file.on('end', () => {
const file_object = {
fieldname,
'originalname': filename,
encoding,
mimetype,
buffer: fileBuffer
}
req.files.file.push(file_object)
})
})
busboy.on('finish', () => {
next()
})
busboy.end(req.rawBody)
req.pipe(busboy)
} else {
next()
}
})}

I have been suffering from the same problem for a few days, turns out that firebase team has put the raw body of multipart/form-data into req.body with their middleware. If you try console.log(req.body.toString()) BEFORE processing your request with multer, you will see your data. As multer creates a new req.body object which is overriding the resulting req, the data is gone and all we can get is an empty req.body. Hopefully the firebase team could correct this soon.

To add to the official Cloud Function team answer, you can emulate this behavior locally by doing the following (add this middleware higher than the busboy code they posted, obviously)
const getRawBody = require('raw-body');
const contentType = require('content-type');
app.use(function(req, res, next){
if(req.rawBody === undefined && req.method === 'POST' && req.headers['content-type'] !== undefined && req.headers['content-type'].startsWith('multipart/form-data')){
getRawBody(req, {
length: req.headers['content-length'],
limit: '10mb',
encoding: contentType.parse(req).parameters.charset
}, function(err, string){
if (err) return next(err);
req.rawBody = string;
next();
});
}
else{
next();
}
});

Cloud functions pre-processes the request object before passing it on further. As such the original multer middleware doesn't work. Furthermore, using busboy is too low level and you need to take care of everything on your own which isn't ideal. Instead you can use a forked version of multer middleware for processing multipart/form-data on cloud functions.
Here's what you can do.
Install the fork
npm install --save emadalam/multer#master
Use startProcessing configuration for custom handling of req.rawBody added by cloud functions.
const express = require('express')
const multer = require('multer')
const SIZE_LIMIT = 10 * 1024 * 1024 // 10MB
const app = express()
const multipartFormDataParser = multer({
storage: multer.memoryStorage(),
// increase size limit if needed
limits: {fieldSize: SIZE_LIMIT},
// support firebase cloud functions
// the multipart form-data request object is pre-processed by the cloud functions
// currently the `multer` library doesn't natively support this behaviour
// as such, a custom fork is maintained to enable this by adding `startProcessing`
// https://github.com/emadalam/multer
startProcessing(req, busboy) {
req.rawBody ? busboy.end(req.rawBody) : req.pipe(busboy)
},
})
app.post('/some_route', multipartFormDataParser.any(), function (req, res, next) {
// req.files is array of uploaded files
// req.body will contain the text fields
})

I ran into this issue today, check here for more details on how to handle files on google cloud (basically you don't need multer).
Here is a middleware I use to extract files. This will keep all your files on request.files and other form fields on request.body for all POST with multipart/form-data content type. It will leave everything else the same for your other middlewares to handle.
// multiparts.js
const { createWriteStream } = require('fs')
const { tmpdir } = require('os')
const { join } = require('path')
const BusBoy = require('busboy')
exports.extractFiles = async(req, res, next) => {
const multipart = req.method === 'POST' && req.headers['content-type'].startsWith('multipart/form-data')
if (!multipart) return next()
//
const busboy = new BusBoy({ headers: req.headers })
const incomingFields = {}
const incomingFiles = {}
const writes = []
// Process fields
busboy.on('field', (name, value) => {
try {
// This will keep a field created like so form.append('product', JSON.stringify(product)) intact
incomingFields[name] = JSON.parse(value)
} catch (e) {
// Numbers will still be strings here (i.e 1 will be '1')
incomingFields[name] = value
}
})
// Process files
busboy.on('file', (field, file, filename, encoding, contentType) => {
// Doing this to not have to deal with duplicate file names
// (i.e. TIMESTAMP-originalName. Hmm what are the odds that I'll still have dups?)
const path = join(tmpdir(), `${(new Date()).toISOString()}-${filename}`)
// NOTE: Multiple files could have same fieldname (which is y I'm using arrays here)
incomingFiles[field] = incomingFiles[field] || []
incomingFiles[field].push({ path, encoding, contentType })
//
const writeStream = createWriteStream(path)
//
writes.push(new Promise((resolve, reject) => {
file.on('end', () => { writeStream.end() })
writeStream.on('finish', resolve)
writeStream.on('error', reject)
}))
//
file.pipe(writeStream)
})
//
busboy.on('finish', async () => {
await Promise.all(writes)
req.files = incomingFiles
req.body = incomingFields
next()
})
busboy.end(req.rawBody)
}
And now in your function, make sure that this is the first middleware you use.
// index.js
const { onRequest } = require('firebase-functions').https
const bodyParser = require('body-parser')
const express = require('express')
const cors = require('cors')
const app = express()
// First middleware I'm adding
const { extractFiles } = require('./multiparts')
app.use(extractFiles)
app.use(bodyParser.urlencoded({ extended: true }))
app.use(bodyParser.json())
app.use(cors({ origin: true }))
app.use((req) => console.log(req.originalUrl))
exports.MyFunction = onRequest(app);

I fixed some bugs G. Rodriguez's response. I add 'field' and 'finish' event for Busboy, and do next() in 'finish' event. This is work for me. As follow:
module.exports = (path, app) => {
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))
app.use((req, res, next) => {
if(req.rawBody === undefined && req.method === 'POST' && req.headers['content-type'].startsWith('multipart/form-data')){
getRawBody(req, {
length: req.headers['content-length'],
limit: '10mb',
encoding: contentType.parse(req).parameters.charset
}, function(err, string){
if (err) return next(err)
req.rawBody = string
next()
})
} else {
next()
}
})
app.use((req, res, next) => {
if (req.method === 'POST' && req.headers['content-type'].startsWith('multipart/form-data')) {
const busboy = new Busboy({ headers: req.headers })
let fileBuffer = new Buffer('')
req.files = {
file: []
}
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
file.on('data', (data) => {
fileBuffer = Buffer.concat([fileBuffer, data])
})
file.on('end', () => {
const file_object = {
fieldname,
'originalname': filename,
encoding,
mimetype,
buffer: fileBuffer
}
req.files.file.push(file_object)
})
})
busboy.on('field', function(fieldname, val, fieldnameTruncated, valTruncated) {
console.log('Field [' + fieldname + ']: value: ' + inspect(val));
});
busboy.on('finish', function() {
next()
});
busboy.end(req.rawBody)
req.pipe(busboy);
} else {
next()
}
})}

Thanks for everyone's help on this thread. I wasted a whole day trying every possible combination and all these different libraries... only to discover this after exhausting all other options.
Combined some of the above solutions to create a TypeScript and middleware capable script here:
https://gist.github.com/jasonbyrne/8dcd15701f686a4703a72f13e3f800c0

If you just want to get a single uploaded file from the request, use busboy to get the file as a readable stream:
const express = require('express')
const Busboy = require('busboy')
express().post('/', (req, res) => {
const busboy = new Busboy({ headers: req.headers })
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
// Do something with `file`, e.g. pipe it to an output stream.
// file.pipe(fs.createWriteStream('upload.pdf')
})
// The original input was moved to `req.rawBody`
busboy.write(req.rawBody)
})

Note that, on top of using Busboy on the server and parsing the rawReq, you may also need to add the following config to your Axios request:
{ headers: { 'content-type': `multipart/form-data; boundary=${formData._boundary}` }};
If you only specify the content-type and not the boundary you get a Boundary not found error on the server. If you remove the headers altogether, instead, Busboy won't parse the fields properly.
See: Firebase Cloud Functions and Busboy not parsing fields or files

I experience the same issue when i deployed my app using firebase function. I was using multer to upload image to amazon s3. I resolve this issue by using the above npm https://stackoverflow.com/a/48648805/5213790 created by Cristóvão.
const { mimetype, buffer, } = req.files[0]
let s3bucket = new aws.S3({
accessKeyId: functions.config().aws.access_key,
secretAccessKey: functions.config().aws.secret_key,
});
const config = {
Bucket: functions.config().aws.bucket_name,
ContentType: mimetype,
ACL: 'public-read',
Key: Date.now().toString(),
Body: buffer,
}
s3bucket.upload(config, (err, data) => {
if(err) console.log(err)
req.file = data;
next()
})
Note that this is for a single file image upload.
The next middleware will have the returned object from s3
{
ETag: '"cacd6d406f891e216f9946911a69aac5"',
Location:'https://react-significant.s3.us-west1.amazonaws.com/posts/1567282665593',
key: 'posts/1567282665593',
Key: 'posts/1567282665593',
Bucket: 'react-significant'
}
In this case, you might need the Location url before you save your data in the db.

I've tried Dougs answer, however the finish was never fired, so i tweaked the code a little bit and got this which works for me:
// It's very crucial that the file name matches the name attribute in your html
app.post('/', (req, res) => {
const busboy = new Busboy({ headers: req.headers })
// This object will accumulate all the uploaded files, keyed by their name
const uploads = {}
// This callback will be invoked for each file uploaded
busboy.on('file', (fieldname, file, filename, encoding, mimetype) => {
console.log(`File [${fieldname}] filename: ${filename}, encoding: ${encoding}, mimetype: ${mimetype}`)
// Note that os.tmpdir() is an in-memory file system, so should only
// be used for files small enough to fit in memory.
const filepath = path.join(os.tmpdir(), filename)
uploads[fieldname] = { file: filepath }
console.log(`Saving '${fieldname}' to ${filepath}`)
const stream = fs.createWriteStream(filepath)
stream.on('open', () => file.pipe(stream))
})
// This callback will be invoked after all uploaded files are saved.
busboy.on('finish', () => {
console.log('look im firing!')
// Do whatever you want here
res.end()
})
// The raw bytes of the upload will be in req.rawBody. Send it to busboy, and get
// a callback when it's finished.
busboy.end(req.rawBody)
})