Health Checks in AWS Route 53 Overview

Key Concepts

• Purpose: Health checks in Route 53 are designed to monitor the health of resources, primarily public but also private.
• High Availability: Employed in multi-region setups to ensure users are redirected to the closest or healthiest load balancer.
• Automated DNS Failover: Route 53 utilizes health checks for automated DNS failover, improving service availability.

Types of Health Checks

1. Endpoint Health Checks: Monitor public endpoints like applications, servers, or other AWS resources.
2. Calculated Health Checks: Monitor the aggregate health of multiple health checks.
3. CloudWatch Alarm Health Checks: Monitor the health based on CloudWatch Alarms, suitable for both public and private resources.

Key Features

• Global Health Checkers: Approximately 15 health checkers worldwide assess the health of endpoints.
• Protocols Supported: HTTP, HTTPS, and TCP.
• Frequency: Standard checks every 30 seconds or fast checks every 10 seconds (higher cost).
• Health Criteria: A resource is considered healthy if it returns a 2xx or 3xx status code. Custom text-based responses can also be evaluated.
• Security: Must allow incoming requests from Route 53 health checker IP ranges for checks to function.

Calculated Health Checks

• Functionality: Combine multiple health checks into a single metric using logical conditions (OR, AND, NOT).
• Capacity: Can monitor up to 256 child health checks.
• Use Cases: Ideal for complex setups requiring aggregate health monitoring or maintenance windows without triggering widespread alerts.

Monitoring Private Resources