# Webhook Service

Webhook delivery service with retry logic and dead letter queue.

## Features

- Webhook registration and management
- Event-based webhook delivery
- Exponential backoff retry logic
- Dead letter queue (DLQ) for failed deliveries
- HMAC-SHA256 payload signing
- Delivery attempt tracking

## API Endpoints

- `POST /v1/webhooks` - Create webhook
- `GET /v1/webhooks/:id` - Get webhook
- `GET /v1/webhooks` - List webhooks
- `PATCH /v1/webhooks/:id` - Update webhook
- `DELETE /v1/webhooks/:id` - Delete webhook
- `POST /v1/webhooks/:id/test` - Test webhook
- `POST /v1/webhooks/:id/replay` - Replay webhooks
- `GET /v1/webhooks/:id/attempts` - Get delivery attempts
- `GET /v1/webhooks/dlq` - List DLQ entries
- `POST /v1/webhooks/dlq/:id/retry` - Retry DLQ entry

## Retry Logic

- Max retries: 3
- Exponential backoff: 1s, 2s, 4s
- Failed deliveries moved to DLQ after max retries

## Webhook Signing

Webhooks can be signed with HMAC-SHA256 using a secret:
- Header: `X-Webhook-Signature`
- Algorithm: HMAC-SHA256
- Secret: Provided during webhook creation

## Configuration

- `REST_API_URL` - Main REST API URL
- `KAFKA_BROKERS` or `NATS_URL` - Event bus connection
- `DLQ_RETENTION_DAYS` - DLQ retention period (default: 30)