[s3-example] 3. 백엔드 구축

백엔드 깃허브 링크

Node.js와 express로 백엔드를 구축했다.

백엔드에서 aws-sdk를 이용하여 버킷과 객체에 접근할 것이다.

환경변수 정의하기

MY_AWS_ACCESS_KEY : IAM 설정에서 발급받은 액세스 키

MY_AWS_SECRET_KEY : IAM 설정에서 발급받은 시크릿 액세스 키

MY_AWS_S3_BUCKET : 버킷 명

MY_AWS_S3_BUCKET_REGION : AWS 리전 (서울이면 ap-northeast-2)

S3 SDK 환경 정의하기

/src/util/aws.js

const { S3Client, PutObjectCommand } = require('@aws-sdk/client-s3');

// 환경 변수를 .env 파일로 관리하게 해주는 라이브러리
require('dotenv').config();

const awsAccessKey = process.env.MY_AWS_ACCESS_KEY;
const awsSecretKey = process.env.MY_AWS_SECRET_KEY;
const awsS3Bucket = process.env.MY_AWS_S3_BUCKET;
const awsS3BucketRegion = process.env.MY_AWS_S3_BUCKET_REGION;

const s3 = new S3Client({
   credentials: {
      accessKeyId: awsAccessKey,
      secretAccessKey: awsSecretKey,
   },
   region: awsS3BucketRegion,
});

const listObjectsBucketParams = () => {
   return {
      Bucket: awsS3Bucket,
      Prefix: ``,
   };
};

const deleteObjectBucketParams = fileName => {
   return {
      Bucket: awsS3Bucket,
      Key: fileName,
   };
};

// 객체를 S3에 업로드하는 함수
async function uploadFile(fileBuffer, fileName, mimetype) {
   const uploadParams = {
      Bucket: awsS3Bucket,
      Key: fileName,
      Body: fileBuffer,
      ContentType: mimetype,
   };

   const res = await s3.send(new PutObjectCommand(uploadParams));
   return res.$metadata.httpStatusCode;
}

module.exports = {
   s3,
   listObjectsBucketParams,
   deleteObjectBucketParams,
   uploadFile,
};

const { S3Client, PutObjectCommand } = require('@aws-sdk/client-s3');

// 환경 변수를 .env 파일로 관리하게 해주는 라이브러리
require('dotenv').config();

const awsAccessKey = process.env.MY_AWS_ACCESS_KEY;
const awsSecretKey = process.env.MY_AWS_SECRET_KEY;
const awsS3Bucket = process.env.MY_AWS_S3_BUCKET;
const awsS3BucketRegion = process.env.MY_AWS_S3_BUCKET_REGION;

const s3 = new S3Client({
   credentials: {
      accessKeyId: awsAccessKey,
      secretAccessKey: awsSecretKey,
   },
   region: awsS3BucketRegion,
});

const listObjectsBucketParams = () => {
   return {
      Bucket: awsS3Bucket,
      Prefix: ``,
   };
};

const deleteObjectBucketParams = fileName => {
   return {
      Bucket: awsS3Bucket,
      Key: fileName,
   };
};

// 객체를 S3에 업로드하는 함수
async function uploadFile(fileBuffer, fileName, mimetype) {
   const uploadParams = {
      Bucket: awsS3Bucket,
      Key: fileName,
      Body: fileBuffer,
      ContentType: mimetype,
   };

   const res = await s3.send(new PutObjectCommand(uploadParams));
   return res.$metadata.httpStatusCode;
}

module.exports = {
   s3,
   listObjectsBucketParams,
   deleteObjectBucketParams,
   uploadFile,
};

API

/src/routes/image.js

const express = require('express');
const formidable = require('formidable');
const { ListObjectsCommand, DeleteObjectCommand } = require('@aws-sdk/client-s3');

const { s3, listObjectsBucketParams, deleteObjectBucketParams, uploadFile } = require('../util/aws');
const fs = require('fs');

const router = express.Router();

// GET: 객체들의 Key값들 반환 ex) [a.PNG, b.PNG]
router.get('/', async (req, res) => {
   try {
      const data = await s3.send(new ListObjectsCommand(listObjectsBucketParams()));

      res.status(200).send(data.Contents.map(item => item.Key));
   } catch (e) {
      res.status(400).send({ error: '이미지 Key 값 가져오기 실패' });
   }
});

// POST: 파일 업로드
router.post('/', async (req, res) => {
   try {
      const fileData = await new Promise((resolve, reject) => {
         const form = new formidable.IncomingForm();

         // formidable로 폼 파싱
         form.parse(req, (err, fields, files) => {
            if (err) return reject(err);
            return resolve({ fields, files });
         });
      });

      const parsedFileData = fileData;

      Object.values(parsedFileData.files).forEach(async item => {
         // fs.createReadStream이용해 스트림 전환 후 올리기
         const fileBuffer = fs.createReadStream(item[0].filepath);
         fileBuffer.on('error', err => console.log(err));

         const fileName = item[0].originalFilename;

         await uploadFile(fileBuffer, fileName, item[0].mimetype);
      });

      return res.status(201).json({
         message: 's3 업로드 성공',
      });
   } catch (e) {
      return res.status(500).json({ error: 's3 업로드 실패' });
   }
});

// DELETE: 객체 삭제
router.delete('/:id', async (req, res) => {
   try {
      await s3.send(new DeleteObjectCommand(deleteObjectBucketParams(req.params.id)));

      return res.status(200).send('이미지 삭제 완료');
   } catch (e) {
      return res.status(500).json({ error: '이미지 삭제 실패' });
   }
});

module.exports = router;

const express = require('express');
const formidable = require('formidable');
const { ListObjectsCommand, DeleteObjectCommand } = require('@aws-sdk/client-s3');

const { s3, listObjectsBucketParams, deleteObjectBucketParams, uploadFile } = require('../util/aws');
const fs = require('fs');

const router = express.Router();

// GET: 객체들의 Key값들 반환 ex) [a.PNG, b.PNG]
router.get('/', async (req, res) => {
   try {
      const data = await s3.send(new ListObjectsCommand(listObjectsBucketParams()));

      res.status(200).send(data.Contents.map(item => item.Key));
   } catch (e) {
      res.status(400).send({ error: '이미지 Key 값 가져오기 실패' });
   }
});

// POST: 파일 업로드
router.post('/', async (req, res) => {
   try {
      const fileData = await new Promise((resolve, reject) => {
         const form = new formidable.IncomingForm();

         // formidable로 폼 파싱
         form.parse(req, (err, fields, files) => {
            if (err) return reject(err);
            return resolve({ fields, files });
         });
      });

      const parsedFileData = fileData;

      Object.values(parsedFileData.files).forEach(async item => {
         // fs.createReadStream이용해 스트림 전환 후 올리기
         const fileBuffer = fs.createReadStream(item[0].filepath);
         fileBuffer.on('error', err => console.log(err));

         const fileName = item[0].originalFilename;

         await uploadFile(fileBuffer, fileName, item[0].mimetype);
      });

      return res.status(201).json({
         message: 's3 업로드 성공',
      });
   } catch (e) {
      return res.status(500).json({ error: 's3 업로드 실패' });
   }
});

// DELETE: 객체 삭제
router.delete('/:id', async (req, res) => {
   try {
      await s3.send(new DeleteObjectCommand(deleteObjectBucketParams(req.params.id)));

      return res.status(200).send('이미지 삭제 완료');
   } catch (e) {
      return res.status(500).json({ error: '이미지 삭제 실패' });
   }
});

module.exports = router;