Upstream groups and origins
An upstream group contains the origins that can serve your application. An HTTP or L4 group selects an upstream group and backend port.
Origin targets
Choose a public IP address or a public DNS hostname. Provide either address or domain, never both. Private, reserved and documentation addresses are rejected. Hostnames are trimmed, lowercased and have one trailing dot removed; wildcards, literal IPs and invalid public DNS names are rejected.
Selection and health
Selection algorithms include round-robin, least-connections, random and source-ip. Active health checks support HTTP, ping, DNS and TCP. Passive checks react to observed failures. Performance thresholds can exclude origins using recent health reports.
| Setting | Default or range |
|---|---|
| Connect timeout | 5000 ms; 1 through 120000 ms |
| Healthy panic threshold | 50 percent; 0 through 100 |
| Request timeout | 15000 ms; 1 through 3600000 ms |
| Idle timeout | 300000 ms; 1 through 3600000 ms |
| Active interval | 180 seconds; 10 through 3600 seconds |
| Tries per check | 3; 1 through 10 |
| Retry delay | 5 seconds; 1 through 60 seconds |
| Active check timeout | 15000 ms; 1000 through 60000 ms |
A health-check result and an application's response test different parts of the request path. Verify both before you rely on an origin. See first origin setup.