Project: Amazon S3, EC2 आणि RDS MySQL वापरून Reels Video Upload App बनवा

By Ravindra Bagale, trainer · LinkedIn · Last updated: 22 October 2026

1. गोष्ट: college fest साठी reels app

College fest ला students नी 30-second reels upload करावेत. शेकडो videos, प्रत्येक 20 ते 80 MB, आणि सगळे phones वर बघणार. Videos EC2 disk वर ठेवले तर disk भरते, दुसऱ्या server ला दिसत नाहीत, आणि instance गेला तर fest गेला.

म्हणून: मोठ्या files S3 मध्ये, छोटी माहिती (कोण, caption, size, key) MySQL मध्ये, आणि EC2 वरचं app फक्त दोन्ही जोडतं.

2. Architecture

हे का लागतं?

प्रत्येक भाग त्याला जमणारं काम करतो. Databases मोठ्या binary files ठेवायला वाईट; S3 "user 7 चे latest 20 reels" सारख्या queries ला वाईट.

हे काय आहे?

3. Upload चे दोन मार्ग

हे का लागतं?

80 MB video server मधून गेला तर त्याचा CPU, memory आणि bandwidth दोनदा (in आणि out) वापरतो. Pre-signed PUT तो थेट S3 ला पाठवतो.

हे काय आहे?

4. Database schema

CREATE DATABASE reels CHARACTER SET utf8mb4;
USE reels;
CREATE TABLE users (
  id INT AUTO_INCREMENT PRIMARY KEY,
  username VARCHAR(50) NOT NULL UNIQUE,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
CREATE TABLE reels (
  id BIGINT AUTO_INCREMENT PRIMARY KEY,
  user_id INT NOT NULL,
  s3_key VARCHAR(512) NOT NULL UNIQUE,
  caption VARCHAR(300),
  duration_sec SMALLINT,
  size_bytes BIGINT NOT NULL,
  content_type VARCHAR(50) DEFAULT 'video/mp4',
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (user_id) REFERENCES users(id),
  INDEX idx_user_created (user_id, created_at)
);
INSERT INTO users (username) VALUES ('ravi'), ('asha');

पूर्ण URL नाही तर key का? Domain बदलू शकतो (S3 → CloudFront → custom domain). Key कधी बदलत नाही; वाचताना URL बनवा.

5. Node.js app (मुख्य)

// app.js  -  npm i express mysql2 @aws-sdk/client-s3 @aws-sdk/s3-request-presigner uuid
const express = require('express');
const mysql = require('mysql2/promise');
const { S3Client, PutObjectCommand, GetObjectCommand, HeadObjectCommand } = require('@aws-sdk/client-s3');
const { getSignedUrl } = require('@aws-sdk/s3-request-presigner');
const { v4: uuid } = require('uuid');

const BUCKET = process.env.BUCKET;            // reels-app-media
const CDN = process.env.CDN_DOMAIN || '';      // dxxxx.cloudfront.net (optional)
const s3 = new S3Client({ region: 'ap-south-1' }); // creds come from the EC2 role
const db = mysql.createPool({ host: process.env.DB_HOST, user: 'app',
  password: process.env.DB_PASS, database: 'reels' });
const app = express();
app.use(express.json());
app.use(express.static('public'));

app.post('/api/upload-url', async (req, res) => {
  const { userId, type, size } = req.body;
  if (type !== 'video/mp4' || size > 100 * 1024 * 1024) return res.status(400).json({ error: 'mp4 up to 100 MB' });
  const key = `reels/u${userId}/${uuid()}.mp4`;
  const url = await getSignedUrl(s3, new PutObjectCommand({ Bucket: BUCKET, Key: key,
    ContentType: type, ContentLength: size }), { expiresIn: 300 });
  res.json({ key, url });
});

app.post('/api/reels', async (req, res) => {
  const { userId, key, caption, duration } = req.body;
  if (!key.startsWith(`reels/u${userId}/`)) return res.status(403).end();
  const head = await s3.send(new HeadObjectCommand({ Bucket: BUCKET, Key: key })); // 404 if missing
  await db.execute('INSERT INTO reels (user_id,s3_key,caption,duration_sec,size_bytes) VALUES (?,?,?,?,?)',
    [userId, key, caption, duration, head.ContentLength]);
  res.status(201).json({ ok: true });
});

app.get('/api/reels', async (req, res) => {
  const [rows] = await db.query('SELECT r.id,u.username,r.s3_key,r.caption,r.duration_sec,r.size_bytes,r.created_at FROM reels r JOIN users u ON u.id=r.user_id ORDER BY r.created_at DESC LIMIT 20');
  for (const r of rows) r.url = CDN ? `https://${CDN}/${r.s3_key}`
    : await getSignedUrl(s3, new GetObjectCommand({ Bucket: BUCKET, Key: r.s3_key }), { expiresIn: 900 });
  res.json(rows);
});

app.listen(3000, () => console.log('reels on :3000'));

Browser बाजू (public/index.html), महत्वाचा भाग:

const f = document.querySelector('#file').files[0];
const r = await fetch('/api/upload-url', {method:'POST', headers:{'Content-Type':'application/json'},
  body: JSON.stringify({userId:1, type:f.type, size:f.size})}).then(x => x.json());
await fetch(r.url, {method:'PUT', headers:{'Content-Type':f.type}, body:f});   // straight to S3
await fetch('/api/reels', {method:'POST', headers:{'Content-Type':'application/json'},
  body: JSON.stringify({userId:1, key:r.key, caption:cap.value, duration:30})});

6. Flask आणि PHP versions

# app.py  -  pip install flask boto3 pymysql
import os, uuid, boto3, pymysql
from flask import Flask, request, jsonify
s3 = boto3.client("s3", region_name="ap-south-1")
B = os.environ["BUCKET"]
db = lambda: pymysql.connect(host=os.environ["DB_HOST"], user="app", password=os.environ["DB_PASS"], database="reels")
app = Flask(__name__)

@app.post("/api/upload-url")
def upload_url():
    j = request.json
    if j["type"] != "video/mp4" or j["size"] > 100*1024*1024: return {"error": "mp4 up to 100 MB"}, 400
    key = f"reels/u{j['userId']}/{uuid.uuid4()}.mp4"
    url = s3.generate_presigned_url("put_object", Params={"Bucket": B, "Key": key, "ContentType": j["type"]}, ExpiresIn=300)
    return {"key": key, "url": url}

@app.post("/api/reels")
def save():
    j = request.json
    size = s3.head_object(Bucket=B, Key=j["key"])["ContentLength"]
    with db() as c, c.cursor() as cur:
        cur.execute("INSERT INTO reels (user_id,s3_key,caption,duration_sec,size_bytes) VALUES (%s,%s,%s,%s,%s)",
                    (j["userId"], j["key"], j["caption"], j["duration"], size)); c.commit()
    return {"ok": True}, 201

<?php // upload-url.php  -  composer require aws/aws-sdk-php
require 'vendor/autoload.php';
$s3 = new Aws\S3\S3Client(['region' => 'ap-south-1', 'version' => 'latest']);
$in = json_decode(file_get_contents('php://input'), true);
$key = sprintf('reels/u%d/%s.mp4', $in['userId'], bin2hex(random_bytes(16)));
$cmd = $s3->getCommand('PutObject', ['Bucket' => getenv('BUCKET'), 'Key' => $key, 'ContentType' => 'video/mp4']);
$url = (string) $s3->createPresignedRequest($cmd, '+5 minutes')->getUri();
header('Content-Type: application/json');
echo json_encode(['key' => $key, 'url' => $url]);

7. IAM role, bucket CORS आणि endpoint

{"Version":"2012-10-17","Statement":[{"Effect":"Allow",
 "Action":["s3:PutObject","s3:GetObject"],"Resource":"arn:aws:s3:::reels-app-media/reels/*"},
 {"Effect":"Allow","Action":"s3:PutObject","Resource":"arn:aws:s3:::reels-app-media/backups/*"}]}

[{"AllowedOrigins":["http://YOUR-EC2-PUBLIC-DNS:3000"],"AllowedMethods":["PUT","GET"],
  "AllowedHeaders":["*"],"ExposeHeaders":["ETag"],"MaxAgeSeconds":3000}]

CORS का: page तुमच्या domain वर पण PUT s3.amazonaws.com ला. CORS शिवाय browser block करतो. HeadObject ला फक्त s3:GetObject का: HEAD GetObject ने authorise होतो.

8. बनवा: पूर्ण lab

कसं करायचं (step by step)

Part A: S3, IAM, network

1. Region ap-south-1. Bucket yourname-reels-media: BPA on, ACLs disabled, versioning Enable, SSE-S3.
2. Bucket › Permissions › CORS › CORS JSON paste (origin = नंतर EC2 address; testing ला *).
3. IAM › Policies › Create: वरचा JSON (तुमच्या bucket सह), name reels-s3-policy.
4. IAM › Roles › Create: EC2, reels-s3-policy attach, name reels-ec2-role.
5. VPC › Security groups: reels-web (22 My IP कडून, 3000 0.0.0.0/0 कडून) आणि reels-db (3306 reels-web कडून).
6. VPC › Endpoints › Create: AWS services, com.amazonaws.ap-south-1.s3, type Gateway, default VPC, त्याचे route tables निवडा.

Part B: RDS आणि EC2

1. RDS › Create database: MySQL 8.0, Free tier, identifier reels-db, master admin, db.t3.micro किंवा db.t4g.micro, 20 GB gp3, Public access No, SG reels-db.
2. EC2 › Launch: Amazon Linux 2023, t3.micro, SG reels-web, IAM instance profile reels-ec2-role.
3. SSH करा. sudo dnf install -y nodejs mariadb105.
4. Role तपासा: aws sts get-caller-identity. अपेक्षित: assumed-role/reels-ec2-role असलेला ARN.
5. mysql -h <rds-endpoint> -u admin -p, schema paste करा, मग CREATE USER 'app'@'%' IDENTIFIED BY 'StrongPass#1'; GRANT SELECT,INSERT ON reels.* TO 'app'@'%';
6. mkdir reels && cd reels && npm init -y && npm i express mysql2 @aws-sdk/client-s3 @aws-sdk/s3-request-presigner uuid, app.js आणि public/index.html बनवा.
7. BUCKET=yourname-reels-media DB_HOST=<rds-endpoint> DB_PASS='StrongPass#1' node app.js. अपेक्षित: reels on :3000.

Part C: test

1. http://EC2-PUBLIC-IP:3000 उघडा, छोटा mp4 निवडा, caption टाका, upload.
2. Browser DevTools › Network: PUT yourname-reels-media.s3.ap-south-1.amazonaws.com ला, status 200.
3. aws s3 ls s3://yourname-reels-media/reels/ --recursive. अपेक्षित: reels/u1/<uuid>.mp4.
4. SELECT s3_key,caption,size_bytes,created_at FROM reels.reels; मध्ये row.
5. curl -s localhost:3000/api/reels: प्रत्येक item ला pre-signed url. उघडा: video चालतो. 15 minutes नंतर AccessDenied.
6. Optional: या bucket वर OAC सह CloudFront (static website chapter प्रमाणे), मग CDN_DOMAIN=dxxxx.cloudfront.net सह restart. का: अनेक viewers साठी cached playback.

9. Cron ने backups

हे का लागतं?

Logs EC2 disk भरतात, आणि server बाहेर copy नसलेला database धोका. Lifecycle rule सह S3 हा स्वस्त backup target.

कसं करायचं (step by step)

# /home/ec2-user/backup.sh
#!/bin/bash
set -e
D=$(date +%F)
mysqldump -h "$DB_HOST" -u admin -p"$DB_ADMIN_PASS" --single-transaction reels | gzip > /tmp/reels-$D.sql.gz
aws s3 cp /tmp/reels-$D.sql.gz s3://yourname-reels-media/backups/mysql/ --storage-class STANDARD_IA
aws s3 sync /var/log/reels/ s3://yourname-reels-media/backups/logs/$(hostname)/
rm -f /tmp/reels-$D.sql.gz

# crontab -e   (2:30 AM every day)
30 2 * * * DB_HOST=... DB_ADMIN_PASS=... /home/ec2-user/backup.sh >> /var/log/reels-backup.log 2>&1

AL2023 वर आधी cron install: sudo dnf install -y cronie && sudo systemctl enable --now crond. चांगलं: password Secrets Manager किंवा ~/.my.cnf (chmod 600) मध्ये, crontab मध्ये नाही. backups/ वर lifecycle rule: 30 दिवसांनी Glacier Instant, 365 ला expire.

10. S3 event notifications

हे का लागतं?

Reel आला की moderators ना alert किंवा thumbnail बनवायचा असेल, app ने S3 poll न करता.

हे काय आहे?

Bucket › Properties › Event notifications › Create: name new-reel, prefix reels/, suffix .mp4, event All object create events, destination SNS topic (moderators ना email) किंवा Lambda function. SNS topic किंवा Lambda ला s3.amazonaws.com allow करणारी resource policy हवी; Lambda साठी console ती जोडतं. अनेक targets आणि filters साठी EventBridge ला events पाठवा.

# Lambda (Python) - logs each new reel
def handler(event, context):
    for r in event["Records"]:
        print(r["s3"]["bucket"]["name"], r["s3"]["object"]["key"], r["s3"]["object"]["size"])

11. Cleanup

1. Event notification, Lambda/SNS topic, CloudFront distribution (आधी disable) delete.
2. EC2 instance terminate. RDS reels-db delete (lab साठी final snapshot skip).
3. S3 › bucket › Empty (सगळी versions), मग Delete.
4. VPC endpoint, security groups reels-web आणि reels-db, role reels-ec2-role आणि policy reels-s3-policy delete.

12. Interview questions

उजळणी, तुलना आणि मुलाखत cards

हा lesson काही मिनिटांत revise करा. Cards phone वर save करा किंवा PNG download करा. प्रत्येक card वरचा QR हा lesson उघडतो.

अजून cards: Ravi Sir's Cards.