Multer S3 Sharp Resizer

Multer S3 Sharp Resizer is a storage engine for multer.

It addresses a common problem you run into when creating a website that should utilize different sizes of images previously uploaded. You can easily setup the storage engine to create multiple versions of an image that has been uploaded.

Multer S3 Sharp Resizer is written completely in TypeScript and thus all types are provided with it.

Setup

To set up the Storage engine with multer you need to create it like this. Now I will be using TypeScript in the following sections but you can set it up with JavaScript just as easy.

Here we want Multer S3 to upload a thumbnail image in addition to the original image. So the configuration of multer would look like this

my-multer.ts

1import AWS from "aws-sdk"
2import multer from "multer"
3import S3SharpStorage from "multer-s3-sharp-resizer";
4import myS3Config from "./somewhere.ts";
5
6const storage = new S3SharpStorage({
7  s3: new AWS.S3(myS3Config),
8  bucket: 'my-bucket',
9  imageFormats: [
10    {
11      fileFormat: 'jpg',
12      folder: 'thumbnails'
13      resize: {
14        width: 100,
15        height: 100
16      }
17    }
18  ]
19});
20
21export default multer({
22  storage
23});

Configuring the route is just the same as in any regular multer setup

route.ts

1import Multer from "./my-multer";
2import express from "express";
3
4const router = express.Router();
5
6router.post('/',
7  multer.single('image'),
8  (req: Request, res: Response): => {
9    res.status(201).json(req.file)
10  }
11)

For additional scenarios please see the multer documentation

Options

And just like this the storage engine is setup. Now there are multiple Options you can choose from.

Option	Default	Type	Mandatory	Description
s3	undefined	AWS.S3	yes	The S3 Service object from aws-sdk
bucket	undefined	string	yes	Bucket you want your files to be stored in
uploadOriginalImage	true	boolean	no	Set to false if you don't want your original image to be uploaded
metadata	See Metadata	Function	no	Function to add metadate to your files.
keybase	see Key Base	Function	no	Function to create a key for your file
imageFormats	[]	see Image Formats	no	The different Image Formats you want to upload

Metadata

If you want to add Metadata to your files you can define the metadata function. It returns an object of type Record<string,string> which will be added as key value metadata pairs to your file.

An example would look like this if we wanted to add a specific category to metadata that was sent in the query params of the http request.

my-multer.ts

1const storage = new S3SharpStorage({
2  s3: new AWS.S3(myS3Config),
3  bucket: 'my-bucket',
4  imageFormats: [
5    {
6      fileFormat: 'jpg',
7      folder: 'thumbnails',
8      resize: {
9        width: 100,
10        height: 100
11      }
12    }
13  ],
14  metadata: (req: Request, file: Express.Multer.File) => {
15    return {
16      category: req.query.category
17    }
18  }
19});

Key Base

By default the Key will be generated as a 16 character hex hash by crypto. However you can replace it with your own function like this. Remember that as we can upload different file formats in this case the key will be without a file ending. In this case we might want to change that instead of setting a category in metadata we want the image to be in the corresponding folder. So this image would in the end go to

bucket/thumbnails/[category]/[key].jpg

my-multer.ts

1const storage = new S3SharpStorage({
2  s3: new AWS.S3(myS3Config),
3  bucket: 'my-bucket',
4  uploadOriginalImage: false,
5  imageFormats: [
6    {
7      fileFormat: 'jpg',
8      folder: 'thumbnails',
9      resize: {
10        width: 100,
11        height: 100
12      }
13    }
14  ],
15  keyBase: (req: Request, file?: Express.Multer.File) => {
16    const hash = crypto.randomBytes(16).toString('hex')
17    return `${req.query.category}/${hash}`
18  }
19});
20

Image Formats

Now we already saw the image formats briefly in the previous sections. Each format determines what file type will be uploaded etc.

Option	Default	Type	Mandatory	Description
fileFormat	undefined	'png', 'jpg', 'webp'	yes	The file type you want to be saved
folder	''	string	no	The folder you want your image to be saved in
resize	undefined	sharp.ResizeOptions	no	Sharp Configuration for your resize. See sharps documentation

You can use all the options for resize that are provided by their API

Deletion of Images

Now the Storage engine comes with a removeKey method which will make sure that if you want to delete an image you just need to provide one key. Now as you most likely will make a request from a website this method will be called including a file extension. It doesn't matter though which one you provide given that you maybe decided to opload webp's as well as jpg's. Multer S3 Storage Engine will find it. To delete a key just implement it like this in your route

my-multer.ts

1import AWS from "aws-sdk"
2import multer from "multer"
3import S3SharpStorage from "multer-s3-sharp-resizer";
4import myS3Config from "./somewhere.ts";
5
6const storage = new S3SharpStorage({
7  s3: new AWS.S3(myS3Config),
8  bucket: 'my-bucket',
9  imageFormats: [
10    {
11      fileFormat: 'jpg',
12      folder: 'thumbnails'
13      resize: {
14        width: 100,
15        height: 100
16      }
17    }
18  ]
19});
20
21export { storage }
22
23export default multer({
24  storage
25});

route.ts

1import { storage } from "./my-multer"
2
3const router = express.Router();
4
5router.delete('/:Filename', async (req: Request, res: Response): => {
6    const deleted = await storage.removeKey(req.params.Filename);
7    res.status(200).json(deleted)
8  }
9)