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Module 4 · Edge: DNS, CDN, Load BalancersDay 03420 min

Reverse Proxies vs Load Balancers

Same picture, different verbs.

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Day 034

Reverse Proxies vs Load Balancers

Client
client
Reverse Proxy
edge
API
service
Auth
service
Static
service
Signal path
Reverse proxy as a routing/policy layer
Client
client
flow
Reverse Proxy
edge
Reverse Proxy
edge
flow
API
service
Reverse Proxy
edge
flow
Auth
service
Memory hook

Reverse Proxies vs Load Balancers: same picture, different verbs

Mental model

move the first decision closer to the user

Design lens

Single point — make it HA.

Recall anchors
FunctionsTools

Why it matters

A reverse proxy stands in front of services and handles cross-cutting concerns: TLS termination, header rewriting, auth, caching. A load balancer also distributes traffic across multiple backends. Most deployments fold both into one tier.

Deep dive

TLS termination at the edge frees backends from cert/cipher work.

Header rewriting (X-Forwarded-For, host, paths) is essential and easy to misconfigure.

Modern proxies (Envoy) carry policy: rate limiting, circuit breaking, observability.

Demo / scenario

Adding a reverse proxy in front of three services.

  1. Single TLS cert at proxy; backends are HTTP.
  2. Path-based routing: /api → API, /static → CDN, /auth → IdP.
  3. Add per-route rate limits.
  4. Capture access logs centrally.

Tradeoffs

  • Single point — make it HA.
  • Misconfigured rewrites cause subtle auth bugs.
  • Adds a hop; usually <2ms.

Diagram

Client
Reverse Proxy
API
Auth
Static
Reverse proxy as a routing/policy layer.

Mind map

Check yourself

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Sources & further reading

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