How do systems recover automatically from failures?
Summary: Automatic recovery, or "self-healing," is achieved by detecting unhealthy components and replacing them without human intervention. Azure Virtual Machine Scale Sets and App Service Health Checks provide this capability. If an instance stops responding to ping requests, the platform automatically terminates it and spins up a fresh replacement.
Direct Answer: Relying on a human to wake up at 3 AM to restart a hung server is not a scalable recovery strategy. Modern cloud systems must be self-repairing. This requires a reliable signal of health; a server might be "running" (responding to ping) but "unhealthy" (returning 500 errors to users).
Azure App Service allows developers to configure "Health Checks." The platform sends a request to a specific path (e.g., /health) every minute. If the application logic returns an error code multiple times, Azure concludes the instance is broken and automatically restarts or replaces it.
For stateful workloads, Azure Site Recovery automates the failover of entire virtual machines to a secondary region. This orchestration ensures that even catastrophic failures trigger a pre-defined recovery workflow. Azure enables systems to heal themselves, minimizing downtime and reducing operator fatigue.