Amazon Cloudfront

Amazon CloudFront

Amazon CloudFront is AWS’s global content delivery network (CDN) that speeds up delivery of web apps, APIs, and media across a massive edge footprint. It’s also a place where surprise charges can creep in—tiered data transfer out, per-request fees, and invalidations add up quickly during peak events. This page blends Grok’s highlights with a pragmatic, FinOps-oriented playbook.

🚀 What is CloudFront?

CloudFront caches and serves content from edge locations close to users, providing low latency and high throughput. It supports static and dynamic content, live and on-demand video, software distribution, and API acceleration. Security is built in (AWS Shield Standard), and you can run logic at the edge with CloudFront Functions or Lambda@Edge.

Common content types

  • Static & dynamic web content (HTML/CSS/JS, images, APIs)

  • Video streaming (HLS/DASH), VOD, live events

  • Software/game updates, IoT firmware

  • GraphQL/REST APIs and real-time feeds

🔗 Quicklinks (console/bookmarks)

  • CloudFront Reports & Analytics → cache hit/miss, popular objects, geos, user agents

  • Real-Time Metrics & Logs → near-real-time KPIs; optional real-time logs via Kinesis

  • WAF web ACLs (attach to distributions), Shield posture

  • Cost Explorer → Service: Amazon CloudFront, group by Usage type (transfer vs requests vs logs/functions)

  • Origin Access Control (OAC) for S3 (preferred over OAI), Origin Shield, Tiered Cache, Price Classes

⚙️ Price Classes — pick the right coverage

Price Class
Coverage
When to pick it

All

Full global edge network

Global audience and strict latency targets.

200

Major metros in North America, Europe, Asia

Balanced performance/cost for multi-region audiences.

100

Top markets (e.g., US, EU, Japan)

Cost-focused when traffic is concentrated in core regions.

Start lean (100 or 200) and expand if you see cache misses or latency from under-served geographies.

🧬 Edge compute options

Option
Runtime & scope
Great for
Notes

CloudFront Functions

Lightweight JS at the viewer context

Header rewrites, redirects, URL normalization, AB tests

Ultra-low latency and low cost; ideal for simple request/response mods.

Lambda@Edge

Node.js at viewer/origin phases

Auth, personalized caching, signed cookies/URLs, complex rewrites

More capabilities & resources than Functions; higher latency/cost; code replicated globally.

Rule of thumb: Functions for fast, simple edge logic; Lambda@Edge when you need origin-time context or heavier processing.

🏛️ Origins & deployment patterns

Origin
Use when
Notes

Amazon S3

Static sites/assets, downloads

Use OAC to lock buckets, avoid public access; pair with cache policies for optimal keys.

ALB / EC2 / ECS / EKS

Dynamic web apps & APIs

Keep origins in the same Region as most users; enable keep-alives; compress at origin.

MediaStore / MediaPackage

Live/OTT streaming

Optimized for media; fine-tune segment sizes and cache headers.

API Gateway

Edge-accelerated APIs

Combine with WAF and JWT/SigV4 auth patterns.

HTTPS everywhere by default; bring your own certs via ACM. Use signed URLs/cookies for private content.

🧠 CloudFront optimization strategy

Strategy
What to do
Why/How

Right-size coverage

Start with Price Class 100/200; expand as needed

Cuts transfer costs without hurting core markets.

Design the cache key

Include only necessary headers/cookies/query params

Smaller key = higher hit ratio. Prefer Cache/Origin Request Policies over legacy behaviors.

Tune TTLs

Long TTLs for immutable assets; short+stale-while-revalidate for dynamic

Improves hit ratio while keeping content fresh. Use content-hashed file names to avoid manual invalidations.

Turn on Tiered Cache & Origin Shield

Route misses through regional caches and a shield Region

Fewer origin fetches, reduced egress, faster warmups.

Compress aggressively

Enable Brotli & Gzip for text; segment size tuning for video

Reduces egress volume; faster time-to-first-byte.

Geo/WAF filtering

Block/shape non-target geos, bots, and L7 attacks

Cuts wasteful traffic and protects origins.

Smart invalidations

Batch paths; avoid wildcard nukes

Prefer content hashing; reserve invalidations for exceptions.

Protocol upgrades

Enable HTTP/2 and HTTP/3 (QUIC)

Better multiplexing and latency for modern clients.

💸 Pricing model & gotchas

  • Pay-as-you-go: charges for Data Transfer Out (DTO) by geographic tier, HTTPS/HTTP requests, optional real-time logs, and edge compute invocations.

  • Origin data transfer: From S3 to CloudFront is typically free (origin fetch); other origins (e.g., ALB/EC2) incur standard inter-service DTO.

  • Free tier (12 months for new accounts): generous monthly allowances for data out and requests; also includes CloudFront Functions invocations and a limited number of invalidation paths.

  • Invalidations: Beyond the free monthly allotment, each path costs—design for immutability to avoid them.

  • Log volume: Standard logs to S3 are cheap but can be voluminous; real-time logs add cost—scope them to critical distributions or short bursts.

  • Edge compute: CloudFront Functions is much cheaper than Lambda@Edge at scale; use the smallest tool that fits.

Cost anatomy to monitor in Cost Explorer: DataTransfer-Out-Bytes, Requests-HTTPS, Requests-HTTP, log delivery, real-time logs (if enabled), Functions/Lambda@Edge invocations.

⏱️ Automation patterns

  • CI/CD cache busting: fingerprint assets (e.g., app.abcd1234.js) so deploys don’t require invalidations.

  • Event-driven invalidation: use EventBridge or pipelines to invalidate only changed paths.

  • IaC: manage distributions via CloudFormation/Terraform/CDK; version cache/origin policies as code.

  • Blue/green at the edge: route by header/cookie for canaries and A/B tests using CloudFront Functions.

🔒 Security & compliance

  • AWS Shield Standard included; add AWS WAF for L7 protections (rate limits, managed rules).

  • Private content: use signed URLs/cookies and OAC (S3) to block direct origin access.

  • TLS: use ACM certs for custom domains; enforce modern ciphers; enable HSTS at the edge if required.

  • PII/PCI: consider Field-Level Encryption for sensitive headers; restrict logs; rotate keys.

  • Zero-trust to origin: keep origins private; allow only CloudFront via security groups or S3 bucket policies with OAC.

📊 Monitoring & tools

  • CloudWatch metrics: cache hit ratio, 4xx/5xx error rates, bytes transferred, function errors.

  • CloudFront Reports: popular objects, geos, user agents; use to drive Price Class and cache-key tuning.

  • Standard logs → S3 and Real-Time Logs → Kinesis: feed SIEMs, bot analysis, and performance dashboards.

  • Cost Explorer & CUR: attribute spend by distribution ID and usage type; alert with AWS Budgets.

🧪 Practical selection cheat-sheet

  • Static sites/assets: S3 + CloudFront (OAC), long TTLs, hashed filenames, Price Class 100/200.

  • Dynamic APIs: ALB/EC2/APIGW origin, short TTLs with stale-while-revalidate, narrow cache key, WAF.

  • Media streaming: MediaPackage/MediaStore origin, appropriate segment sizes, Origin Shield, HTTP/2/3.

  • Personalization at edge: start with CloudFront Functions; move to Lambda@Edge only if you need origin-time context or more resources.

  • Global product: start with Price Class 200, add regions (All) where latency/traffic justifies it.

✅ Checklist

References (add your org’s canonical links)

  • CloudFront pricing (DTO tiers, requests, logs, edge compute)

  • CloudFront Reports & Real-Time Logs docs

  • Origin Access Control (OAC) and S3 private origin patterns

  • Tiered Cache, Origin Shield, Cache/Origin Request Policies

  • WAF integration & managed rule groups

  • Cost Explorer/CUR guide for CloudFront charge types

Pricing/features change—verify in your Region before rollout, especially for new edge features and DTO tiers.

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