Reverse Proxy (Web Server)

Understanding reverse proxies, their benefits, and comparison with load balancers

A reverse proxy is a web server that centralizes internal services and provides unified interfaces to the public. Requests from clients are forwarded to a server that can fulfill it before the reverse proxy returns the server’s response to the client.

Benefits

Additional benefits include:

• Increased security - Hide information about backend servers, blacklist IPs, limit number of connections per client
• Increased scalability and flexibility - Clients only see the reverse proxy’s IP, allowing you to scale servers or change their configuration
• SSL termination - Decrypt incoming requests and encrypt server responses so backend servers do not have to perform these potentially expensive operations
  • Removes the need to install X.509 certificates on each server
• Compression - Compress server responses
• Caching - Return the response for cached requests
• Static content - Serve static content directly
  • HTML/CSS/JS
  • Photos
  • Videos
  • Etc

Load Balancer vs Reverse Proxy

When to Use Each

• Load Balancer: Deploying a load balancer is useful when you have multiple servers. Often, load balancers route traffic to a set of servers serving the same function.

• Reverse Proxy: Reverse proxies can be useful even with just one web server or application server, opening up the benefits described in the previous section.

• Both: Solutions such as NGINX and HAProxy can support both layer 7 reverse proxying and load balancing.

A reverse proxy can be beneficial even with a single backend server, while load balancers are specifically designed for distributing traffic across multiple servers.

Key Differences

Aspect	Load Balancer	Reverse Proxy
Primary Purpose	Distribute traffic across multiple servers	Centralize and manage access to backend services
Minimum Servers	Multiple servers	Can work with single server
Use Case	High availability and horizontal scaling	Security, caching, SSL termination, serving static content

Disadvantages of Reverse Proxy

• Introducing a reverse proxy results in increased complexity.
• A single reverse proxy is a single point of failure, configuring multiple reverse proxies (ie a failover) further increases complexity.

Source(s) and Further Reading

• Reverse proxy vs load balancer
• NGINX architecture
• HAProxy architecture guide
• Wikipedia - Reverse proxy