What is HTTP 503 Service Unavailable?
The 503 Service Unavailable status code indicates that a server cannot currently process requests.
Unlike permanent failures, 503 responses usually indicate a temporary condition.
Common Causes
- Server maintenance
- Traffic spikes
- Overloaded infrastructure
- Failed health checks
- Insufficient resources
DevOps Examples
- Kubernetes pods unavailable
- Load balancer health checks failing
- Application scaling delays
- Scheduled maintenance windows
Troubleshooting
Investigate application availability, infrastructure metrics, and deployment changes.
Summary
The 503 Service Unavailable response indicates temporary inability to serve requests.