Delivery Guarantees

At-Least-Once Delivery

HookSniff guarantees at-least-once delivery. This means:

• Every webhook will be delivered at least once
• If delivery fails, it will be retried automatically
• If all retries fail, the event is preserved in the DLQ
• You can replay failed deliveries at any time

Important:"At-least-once" means duplicates are possible. Your endpoint should be idempotent — able to handle the same event multiple times without side effects.

Why Not Exactly-Once?

Exactly-once delivery is theoretically impossible in distributed systems. The network can always fail between "I sent it" and "I got the response."

The practical solution is at-least-once delivery + idempotent consumers. HookSniff provides the delivery guarantee; you provide the idempotency.

How to Be Idempotent

Track processed delivery IDs and skip duplicates:

CREATE TABLE processed_webhooks (
  delivery_id TEXT PRIMARY KEY,
  processed_at TIMESTAMPTZ DEFAULT NOW()
);

-- Before processing:
SELECT 1 FROM processed_webhooks WHERE delivery_id = $1;
-- If exists, skip. If not, process and insert.

What Can Go Wrong?