Load balancing (NGINX, HAProxy, AWS ELB)
Keepalived is an open-source software used primarily for high-availability and load-balancing solutions in network environments. It is commonly deployed to ensure failover and redundancy by monitoring the health of services or network interfaces. When a failure is detected on a primary server or network interface, Keepalived automatically switches traffic to a backup server or interface, maintaining service continuity.
Key Features:
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High Availability (HA): Keepalived ensures that if a primary node in a network or server cluster fails, the service is automatically transferred to a backup node. This is achieved using Virtual Router Redundancy Protocol (VRRP), which creates a virtual IP address shared between the primary and backup nodes.
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Load Balancing: It can be used to distribute incoming traffic among multiple servers, allowing better performance, scalability, and reliability.
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Health Checks: Keepalived performs periodic health checks on services or network interfaces. If it detects that a service has failed, it can automatically take corrective action (e.g., restarting a service, switching to a backup, etc.).
Use Cases:
- Failover and Redundancy: Ensuring that if a critical service or interface fails, there’s no downtime.
- Load Balancing: Distributing network traffic across multiple servers to avoid overloading a single server.
- Network Interface Monitoring: Monitoring and managing network interfaces to switch between active and backup routes if an issue is detected.
Example:
A typical example of Keepalived in action is in a web server environment where two or more servers share the same virtual IP. If one server goes down, Keepalived automatically redirects the traffic to the backup server without affecting users.
For more details, you can check Keepalived's official website.