multer-imager-storage.ts

import * as path from 'path';
import * as imager from 'multer-imager';
import * as dotenv from 'dotenv';
import * as fs from 'fs';

const ENV = process.env.NODE_ENV;

if (!ENV) {
    const envFilePath = path.resolve(process.cwd(), 'env', !ENV ? '.env' : `.env.${ENV}`);
    const envConfig = dotenv.parse(fs.readFileSync(envFilePath));
    for (const k in envConfig) {
        if (envConfig.hasOwnProperty(k)) {
            process.env[k] = envConfig[k];
        }
    }
}

export const multerImagerStorage = imager({
    dirname: 'images',
    bucket: process.env.S3_BUCKET,
    accessKeyId: process.env.S3_ACCESS_KEY,
    secretAccessKey: process.env.S3_ACCESS_SECRET,
    region: process.env.S3_REGION,
    gm: {                                 // [Optional]: define graphicsmagick options
        width: 100,                         // doc: http://aheckmann.github.io/gm/docs.html#resize
    },
    s3: {                                // [Optional]: define s3 options
        Metadata: {                         // http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPUT.html
            ACL: 'public-read',
        },
    },
    filename: (req, file, cb) => {
        const datetimestamp = Date.now();
        const extenstion = path.extname(file.originalname);
        let fileName = path.basename(file.originalname, extenstion);
        // replace special chars with hyphen and remove extra hyphens
        fileName = fileName.replace(/[^a-zA-Z]/g, '-').replace(/-{2,}/g, '-');
        // check if lenght more than 20 then trim
        fileName = fileName.substring(0, 20).toLowerCase();
        // callback
        cb(null, datetimestamp + '-' + fileName + extenstion);
    },
});

multer-s3-storage.ts

import * as AWS from 'aws-sdk';
import * as multerS3 from 'multer-s3';
import * as path from 'path';
import * as dotenv from 'dotenv';
import * as fs from 'fs';

const ENV = process.env.NODE_ENV;

if (!ENV) {
    const envFilePath = path.resolve(process.cwd(), 'env', !ENV ? '.env' : `.env.${ENV}`);
    const envConfig = dotenv.parse(fs.readFileSync(envFilePath));
    for (const k in envConfig) {
        if (envConfig.hasOwnProperty(k)) {
            process.env[k] = envConfig[k];
        }
    }
}

const s3 = new AWS.S3();

AWS.config.update({
    accessKeyId: process.env.S3_ACCESS_KEY,
    secretAccessKey: process.env.S3_ACCESS_SECRET,
    region: process.env.S3_REGION,
});

export const multerS3Storage = multerS3({
    s3,
    bucket: process.env.S3_BUCKET,
    acl: 'public-read',
    metadata: (req, file, cb) => {
        cb(null, { fieldName: file.fieldname });
    },
    key: (req, file, cb) => {
        const datetimestamp = Date.now();
        const extenstion = path.extname(file.originalname);
        let fileName = path.basename(file.originalname, extenstion);
        // replace special chars with hyphen and remove extra hyphens
        fileName = fileName.replace(/[^a-zA-Z]/g, '-').replace(/-{2,}/g, '-');
        // check if lenght more than 20 then trim
        fileName = fileName.substring(0, 20).toLowerCase();
        // callback
        cb(null, datetimestamp + '-' + fileName + extenstion);
    },
});

s3-multer-options.ts

import * as path from 'path';
import { UnsupportedMediaTypeException } from '@nestjs/common';
import { MulterOptions } from '@nestjs/platform-express/multer/interfaces/multer-options.interface';
import { multerImagerStorage } from './multer-imager-storage';
import { multerS3Storage } from './multer-s3-storage';

export const s3MulterOptions: MulterOptions = {
    storage: multerS3Storage,
    limits: {
        // tslint:disable-next-line: radix
        fileSize: parseInt(process.env.S3_MAX_FILE_LIMIT || '5') * 1024 * 1024, // 5MB
    },
    fileFilter: (req, file, callback) => {
        const ext = path.extname(file.originalname);
        if (ext !== '.png' && ext !== '.jpg' && ext !== '.jpeg') {
            return callback(new UnsupportedMediaTypeException('Only images are allowed'), false);
        }
        return callback(null, true);
    },
};