Object Storage + CDN

Mở đầu

Sao file upload/download chậm? User HCM download file lưu Singapore server, mỗi giây mất ~50ms RTT. Object storage + CDN giải cả 2: lưu cheap + access fast.

1. Object Storage: "smart cloud warehouse"

Storage trên cloud có 3 type

Type	Vd	Use	Cost
Block	AWS EBS, GCP Persistent Disk	OS disk, DB	Cao
File	AWS EFS, Azure Files	Shared filesystem	Trung
Object	AWS S3, GCP Cloud Storage, R2	File, image, video, backup	Thấp nhất

Object storage là gì?

Object = file + metadata + unique key. Không có directory structure thật, flat namespace với "/" trong key giả lập folder.

my-bucket/
├── images/photo1.jpg     ← Key: "images/photo1.jpg"
├── videos/intro.mp4
└── docs/readme.md

Đặc điểm

Unlimited scale: TB → PB → EB
Cheap: ~$0.023/GB/month (S3 Standard)
Durable: 99.999999999% (11 nines)
Access via HTTP: GET/PUT/DELETE
No FS feature: không rename atomically, không append efficient
Eventual consistency (S3 strong consistency từ 2020)

Provider comparison

Provider	Pros	Cons	Pricing/GB/month
AWS S3	Standard, mature ecosystem	Expensive egress	$0.023
Cloudflare R2	Zero egress fee	New, ecosystem nhỏ hơn	$0.015
Backblaze B2	Cheapest, S3-compatible	Less features	$0.006
GCP Storage	Good integration	Egress đắt	$0.020
MinIO	Self-host, S3-compatible	Self-manage	Hardware cost

Cloudflare R2 = game-changer

R2 zero egress fee = nếu site serve nhiều media → cost giảm 90%. AWS S3 charge $0.09/GB egress, R2 = $0.

2. CDN: "global delivery network"

Vấn đề: latency địa lý

User HCM → server Virginia US:

Distance: ~14000 km
RTT: ~250ms
Each request: 250ms latency cố định

CDN solve: cache file ở edge nodes gần user.

User HCM → CDN edge Singapore (5ms) → file
                                      ↓ if miss
                                      Origin US (200ms) → CDN cache → User

CDN architecture

                  ┌─→ Edge HCM
                  ├─→ Edge HN
Origin (US) ──→ │ ├─→ Edge SG
                  ├─→ Edge JP
                  └─→ Edge KR

Each edge cache popular file. Cache miss → fetch origin, save edge, serve.

Providers

Provider	Pricing	VN POP	Note
Cloudflare	Free tier mạnh	HCM, HN	DDoS protection built-in
AWS CloudFront	Pay-per-use	HCM, HN	Tích hợp S3
BunnyCDN	Pay-per-use, cheap	HCM, HN	Cost-effective
Akamai	Enterprise, đắt	HCM, HN	Mature, premium
Fastly	Pay-per-use	SG	Edge compute mạnh

3. Full path: upload → access

1. User upload (browser → S3)
   - Get pre-signed URL từ BE
   - PUT directly đến S3
   - BE chỉ handle metadata
   
2. Process (Lambda trigger)
   - S3 event → Lambda
   - Resize image, generate thumbnail
   - Write back S3
   
3. CDN cache
   - User request: cdn.example.com/photo.jpg
   - Edge cache miss → fetch origin S3
   - Save edge, return user
   
4. Subsequent access (fast)
   - Other users → same edge
   - Cache hit, 5ms response

Pre-signed URL (S3 best practice)

python

import boto3

s3 = boto3.client('s3')
url = s3.generate_presigned_url(
    'put_object',
    Params={'Bucket': 'my-bucket', 'Key': 'uploads/photo.jpg'},
    ExpiresIn=3600  # 1 hour
)
# Send URL to FE → FE PUT direct to S3

Lợi:

BE không proxy file → save bandwidth + CPU
Temporary credential → secure
Multi-part upload support → resume large file

4. Traffic routing: "nearest" node

CDN dùng:

GeoDNS: DNS resolve theo IP user → nearest edge
Anycast: cùng IP advertise nhiều location → BGP route closest
Real User Monitoring (RUM): measure real latency, optimize routing

Configure

# DNS CNAME
cdn.example.com  → CNAME → mybucket.s3.amazonaws.com (origin)

Cloudflare: thêm domain → orange cloud → traffic qua CDN auto.

5. HTTPS optimization

CDN handle TLS termination → backend HTTP (faster).

User (HTTPS) → CDN edge (TLS terminate) → Origin (HTTP)

Modern HTTPS optimization

HTTP/3 + QUIC: 0-RTT handshake
TLS 1.3: 1 round trip
OCSP stapling: server include cert revocation status
HSTS: force HTTPS, prevent downgrade attack

6. Analytics: đọc CDN report

Metric	Note	Healthy
Cache hit rate	% serve từ cache	>80%
Bandwidth	Total traffic	Watch cost
Top URLs	File popular nhất	Optimize hot file
Top origins	Countries top	Strategic edge placement
5xx error rate	Origin/edge fail	<0.1%

7. Practical: build image acceleration từ 0

python

# 1. Upload với pre-signed URL
import boto3
s3 = boto3.client('s3')

# FE call backend này
url = s3.generate_presigned_url('put_object',
    Params={'Bucket': 'my-images', 'Key': f'uploads/{uuid}.jpg', 'ContentType': 'image/jpeg'},
    ExpiresIn=3600
)
return {'upload_url': url}

# FE upload trực tiếp S3

yaml

# 2. Lambda process (S3 event trigger)
import boto3
from PIL import Image
import io

def lambda_handler(event, context):
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = event['Records'][0]['s3']['object']['key']
    
    s3 = boto3.client('s3')
    obj = s3.get_object(Bucket=bucket, Key=key)
    img = Image.open(obj['Body'])
    
    # Generate thumbnail
    img.thumbnail((200, 200))
    out = io.BytesIO()
    img.save(out, format='JPEG', quality=85)
    out.seek(0)
    
    # Save thumbnail
    thumb_key = key.replace('uploads/', 'thumbnails/')
    s3.put_object(Bucket=bucket, Key=thumb_key, Body=out, ContentType='image/jpeg')

# 3. CDN config (Cloudflare)
# DNS: cdn.example.com → CNAME → my-images.s3.amazonaws.com
# Cache rule: Cache everything, TTL 7 days
# Image optimization: Polish on (compress + WebP)

html

<!-- 4. Use trong app -->
<img src="https://cdn.example.com/thumbnails/photo.jpg" loading="lazy">

Lifecycle rules

json

{
  "Rules": [{
    "ID": "DeleteOldTempFiles",
    "Status": "Enabled",
    "Filter": {"Prefix": "temp/"},
    "Expiration": {"Days": 7}
  }, {
    "ID": "ArchiveOldUploads",
    "Status": "Enabled",
    "Filter": {"Prefix": "uploads/"},
    "Transitions": [{"Days": 90, "StorageClass": "GLACIER"}]
  }]
}

Bandwidth cap (tránh cost spike)

Cloudflare: dashboard → Bandwidth Alert
AWS: Budget alert + S3 request metric alarm

8. Object Storage + CDN: golden rules

Pre-signed URL upload: FE upload thẳng S3, không qua backend
CDN cache aggressively: static asset TTL >7 ngày, dùng hash filename
Lifecycle policy: temp file auto delete, old file archive
Image optimization: compress + WebP/AVIF
Lazy load: <img loading="lazy"> save bandwidth
Monitor cost: alert bandwidth + storage threshold
HTTPS everywhere: TLS 1.3, HTTP/3 nếu CDN support

9. Code templates

python

# S3 upload with pre-signed URL
def get_upload_url(filename):
    return s3.generate_presigned_url('put_object',
        Params={'Bucket': BUCKET, 'Key': f'uploads/{uuid4()}/{filename}'},
        ExpiresIn=3600
    )

# CloudFront signed URL (paid content)
def get_signed_url(key):
    return cloudfront_signer.generate_presigned_url(
        f'https://cdn.example.com/{key}',
        date_less_than=datetime.now() + timedelta(hours=1)
    )

# Cache invalidation (CDN purge)
boto3.client('cloudfront').create_invalidation(
    DistributionId='ABCDEFG',
    InvalidationBatch={
        'Paths': {'Quantity': 1, 'Items': ['/images/*']},
        'CallerReference': str(uuid4())
    }
)

10. Glossary

Term	Plain
Object Storage	Storage file qua HTTP, scale unlimited
Bucket	Container chứa object trong S3
Key	Unique identifier cho object
Pre-signed URL	Temp URL cấp permission action 1 lần
CDN	Network global cache file gần user
Edge / POP	Cache server tại region
Origin	Source server (S3, web server)
Cache hit rate	% request serve từ cache, không từ origin
TTL	Cache lifetime
Purge / Invalidation	Force clear cache CDN

2026 cho VN dev

Modern stack 2026:
- Cloudflare R2 + Workers: zero egress + edge compute
- AWS S3 + CloudFront: standard enterprise
- BunnyCDN: cost-effective alternative
VN context:
- VN startup: Cloudflare R2 + Cloudflare CDN = cost killer
- VN enterprise: AWS S3 + CloudFront
- VN local: Viettel Object Storage, FPT Cloud
AI scenario: store image input + LLM output trong R2, CDN serve để giảm cost + latency
Image optimization: Cloudflare Polish, Vercel Image Optimization auto WebP + resize

Object Storage + CDN ​

1. Object Storage: "smart cloud warehouse" ​

Storage trên cloud có 3 type ​

Object storage là gì? ​

Đặc điểm ​

Provider comparison ​

2. CDN: "global delivery network" ​

Vấn đề: latency địa lý ​

CDN architecture ​

Providers ​

3. Full path: upload → access ​

Pre-signed URL (S3 best practice) ​

4. Traffic routing: "nearest" node ​

Configure ​

5. HTTPS optimization ​

Modern HTTPS optimization ​

6. Analytics: đọc CDN report ​

7. Practical: build image acceleration từ 0 ​

Lifecycle rules ​

Bandwidth cap (tránh cost spike) ​

8. Object Storage + CDN: golden rules ​

9. Code templates ​

10. Glossary ​

Object Storage + CDN

1. Object Storage: "smart cloud warehouse"

Storage trên cloud có 3 type

Object storage là gì?

Đặc điểm

Provider comparison

2. CDN: "global delivery network"

Vấn đề: latency địa lý

CDN architecture

Providers

3. Full path: upload → access

Pre-signed URL (S3 best practice)

4. Traffic routing: "nearest" node

Configure

5. HTTPS optimization

Modern HTTPS optimization

6. Analytics: đọc CDN report

7. Practical: build image acceleration từ 0

Lifecycle rules

Bandwidth cap (tránh cost spike)

8. Object Storage + CDN: golden rules

9. Code templates

10. Glossary