Load Balancer Generator
Configure highly available TCP/HTTP load balancers with active health checks.
Configuration Health
High availability analysis for the configured load balancer.
Detailed Analysis
Best Practice Analysis
- Use at least two backend servers for true HA.
- Enable active health checks (HAProxy).
- Ensure frontend and backend ports match your firewall rules.
Production Readiness
- Valid Upstreams
- Health Checks Active
Overview
The Load Balancer Configuration Generator helps you scale your applications horizontally across multiple backend servers using NGINX or HAProxy.
When a single server can no longer handle the traffic volume, a load balancer acts as a traffic cop, sitting in front of your servers and routing client requests across all servers capable of fulfilling them in a manner that maximizes speed and capacity utilization. This tool ensures no single server gets overworked, automatically handling degraded servers with built-in health checks.
How It Works
1. Define Upstreams: Enter the IP addresses or hostnames of your backend application servers. These form the 'upstream pool'.
2. Choose an Algorithm: Select how traffic is distributed. Round Robin cycles through servers sequentially. Least Connections sends traffic to the server with the fewest active requests. IP Hash ensures a specific user always hits the same backend server (useful for session state).
3. Configure Health Checks: Enable active (HAProxy) or passive (NGINX) health checks. If a backend server fails to respond, the load balancer temporarily removes it from the pool until it recovers.
4. Session Persistence: If your application stores user sessions in memory (instead of a shared database like Redis), you can enable sticky sessions to bind a user's session to a specific server via cookies.
Best Practices
- Always use **Least Connections** (`least_conn`) instead of Round Robin if your application has long-lived requests or unpredictable response times. This prevents slow requests from piling up on a single server.
- If your application uses WebSockets, ensure you increase the `proxy_read_timeout`. Load balancers typically drop idle HTTP connections after 60 seconds, which will prematurely disconnect WebSocket users.
- Configure `max_fails` and `fail_timeout` on your upstream servers to instruct the load balancer exactly when to consider a node 'dead' and how long to wait before retrying it.
- Offload SSL/TLS termination at the load balancer layer. This significantly reduces the CPU load on your backend application servers.
Common Mistakes
- Using IP Hashing behind Cloudflare or another CDN. Because all traffic comes from the CDN's IP addresses, IP Hashing will route *all* traffic to a single backend server, entirely defeating the load balancer.
- Forgetting to share session state (e.g., PHP sessions) between backend servers without enabling Sticky Sessions. Users will randomly get logged out as they are routed to different nodes.
- Not setting `proxy_set_header X-Forwarded-For`. Without this, every backend server will think every request is coming from the internal IP of the Load Balancer.
Security Recommendations
- Place your backend application servers on a private network (VPC/LAN) that is completely isolated from the internet. Only the Load Balancer should have a public IP address.
- Configure a WAF (Web Application Firewall) at the load balancer layer to filter malicious traffic before it ever reaches your application servers.
- Set strict Connection Limits (`conn_limit`) per IP address at the load balancer to mitigate volumetric DDoS attacks.
Production Tips
- Enable Keep-Alive between the Load Balancer and the backend servers. This prevents the load balancer from having to negotiate a new TCP handshake for every single request forwarded to the backend.
- If using HAProxy, use the `httpchk` option to make HAProxy explicitly request a `/health` endpoint on your app. TCP checks only verify the port is open; HTTP checks verify the app is actually alive.
- Set a backup server (`backup` flag) in your upstream pool that only receives traffic if all primary servers fail. This is perfect for showing a static 'Maintenance Mode' page.