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High-performance TCP/HTTP load balancer and proxy server

Core Idea: HAProxy is an open-source software solution providing high availability, load balancing, and proxying for TCP and HTTP-based applications, known for its reliability, performance, and low resource consumption.

Key Elements

Key Features

• Layer 4 (TCP) and Layer 7 (HTTP) load balancing
• SSL/TLS termination
• Health checking of backend servers
• Sticky sessions and persistence
• Access control lists (ACLs)
• Content switching and redirection
• Detailed monitoring and statistics
• Zero-downtime reloads

Technical Specifications

• Event-driven, single-process model
• Non-blocking architecture
• Extremely low latency (microseconds)
• Support for tens of thousands of concurrent connections
• Configurable load balancing algorithms
• Advanced queuing mechanisms
• Header manipulation and rewriting
• WebSocket support

Architecture Components

• Frontend: Defines listening sockets and their behaviors
• Backend: Defines groups of servers to handle requests
• Listen: Combined frontend and backend for simpler configuration
• ACLs: Conditions for request manipulation
• Stick Tables: For persistence and rate limiting
• Health Checks: For server availability monitoring

Implementation Example

Basic HAProxy configuration (haproxy.cfg):

global log /dev/log local0 user haproxy group haproxy maxconn 50000 daemon

defaults log global mode http option httplog option dontlognull timeout connect 5000 timeout client 50000 timeout server 50000

frontend http_front bind *:80 stats uri /haproxy?stats default_backend web_servers

backend web_servers balance roundrobin option httpchk HEAD / HTTP/1.1\r\nHost:\ localhost server web1 192.168.1.10:80 check server web2 192.168.1.11:80 check

Load Balancing Algorithms

• Round Robin: Requests distributed in rotation
• Least Connections: Sent to server with fewest connections
• Source IP Hash: Based on client's IP address
• URI Hash: Based on request URI
• URL Parameter: Based on query string parameter
• Header: Based on HTTP header value
• Random: Random distribution with weighting

Use Cases

• High-traffic website load balancing
• API gateway functionality
• Database load balancing
• Service discovery integration
• Microservices architecture entry point
• TCP protocol proxying (MySQL, SMTP, etc.)
• Zero-downtime application deployments

Additional Connections

• Broader Context: Load Balancers, Reverse Proxy
• Applications: High Availability Architecture, Web Infrastructure
• See Also: Nginx, Traefik, Envoy (alternative proxies)

References

1. HAProxy official documentation: https://www.haproxy.org/
2. "Load Balancing with HAProxy" by Nick Ramirez

#load-balancing #high-availability #networking #infrastructure #reverse-proxy

Connections:

Sources:

• From: Worklog n8n