n8n Webhook Circuit Breaker for External APIs with Redis

Protect your external APIs with a Redis-backed circuit breaker (n8n Webhook)

This n8n automation workflow exposes a webhook-based circuit breaker that routes requests only to approved external APIs, monitors failures in Redis, and temporarily blocks calls when error thresholds are exceeded—optionally alerting you via a Slack-compatible webhook.

What this workflow does

• Receives a POST webhook containing a service name, plus the target path, method, and payload.
• Validates inputs by checking the service against a configured allowlist, then builds the target URL. Unknown services or unsafe paths are rejected with 404.
• Checks circuit state in Redis to decide whether to:
  • Allow the call
  • Immediately reject with 503 and a Retry-After header
  • Move into a half-open state after the cool-down
• Half-open probing: in half-open, it claims a single probe slot in Redis so only one request tests recovery; others receive 503.
• Calls the external API with a configured timeout and classifies failures as:
  • Network/timeout errors
  • HTTP 5xx
  • HTTP 408
  (Other 4xx responses do not count as service failures.)
• Updates Redis + responds: on success, it returns the upstream response (and closes the circuit if it was a probe). On failure, it increments a Redis failure counter, opens the circuit when the threshold is reached, optionally sends an alert via an HTTP webhook, and returns a 502 describing the failure and circuit status.

Use cases

• Reduce outages by preventing repeated calls to failing third-party services.
• Enforce allowlisted routing for external API access via a single n8n webhook.
• Protect SaaS reliability with automated backoff and Slack-style incident alerts.

Technical details

• Nodes/logic: webhook, redis, if, set, code, and sticky note.
• Requires Redis credentials on every Redis step and a reachable Redis instance from n8n.
• Supports optional alerting through a Slack-compatible HTTP webhook.