Fallback Origin

Automatic failover to backup origins on error or timeout

Overview

Fallback origin provides automatic failover when the primary origin encounters errors, timeouts, or returns specific status codes. The fallback is evaluated after any configured retry budget is exhausted and before error pages. If the fallback also fails, error pages are evaluated.

Capabilities

  • Trigger on transport errors (connection refused, DNS failure, TLS errors)
  • Trigger on request timeouts
  • Trigger on specific HTTP status codes (e.g., 502, 503, 504)
  • Request rules to restrict which requests are eligible for fallback
  • Configurable max_depth to prevent infinite fallback chains
  • Debug header option to identify fallback responses

Example

Fail over to a backup backend on errors or 5xx status codes:

proxy:
  http_bind_port: 8080

origins:
  "api.example.com":
    action:
      type: proxy
      url: https://test.sbproxy.dev
    fallback_origin:
      action:
        type: proxy
        url: https://test.sbproxy.dev/health
      on_error: true
      on_timeout: true
      on_status:
        - 502
        - 503
        - 504

Test it:

curl -H "Host: api.example.com" http://localhost:8080/
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