Storage Sink Delivery

Storage sink delivery writes events to object storage instead of sending HTTP requests. Use this when you need to archive events, feed a data pipeline, or batch-process webhooks asynchronously.

Supported providers

Provider	Config key	Description
Amazon S3	`s3`	Native S3 support
S3-compatible	`s3`	MinIO, LocalStack, DigitalOcean Spaces, Backblaze B2, etc.
Local filesystem	`local`	Writes NDJSON files to a local directory — useful for self-hosted runs and dev.

Create a storage sink endpoint

Set deliveryMode to storage when creating an endpoint:

curl -X POST https://app.mittr.io/api/v1/endpoints \
  -H "X-API-Key: mtr_your_key" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "s3://my-webhook-archive/events/",
    "deliveryMode": "storage",
    "eventTypes": ["order.*"],
    "storageConfig": {
      "provider": "s3",
      "bucket": "my-webhook-archive",
      "prefix": "events/",
      "region": "us-east-1",
      "accessKeyId": "AKIA...",
      "secretAccessKey": "...",
      "batchSize": 100,
      "flushIntervalSeconds": 60
    }
  }'

Configuration

S3 / S3-compatible

Field	Required	Description
`provider`	Yes	`s3`
`bucket`	Yes	Bucket name
`prefix`	No	Object key prefix (e.g., `events/production/`)
`region`	Yes	AWS region (e.g., `us-east-1`)
`accessKeyId`	Yes	AWS access key
`secretAccessKey`	Yes	AWS secret key
`endpoint`	No	Custom endpoint URL for S3-compatible stores
`batchSize`	No	Events per file (default: 100)
`flushIntervalSeconds`	No	Max seconds between writes (default: 60)

Object format

Events are written as newline-delimited JSON (NDJSON). Each line is a complete event:

{"id":"evt_abc","eventType":"order.created","payload":{"orderId":"ord_123"},"createdAt":"2026-04-14T10:30:00Z"}
{"id":"evt_def","eventType":"order.updated","payload":{"orderId":"ord_123","status":"shipped"},"createdAt":"2026-04-14T10:31:00Z"}

Object key pattern

Objects are named with the flush timestamp and a batch counter:

{prefix}{date}/{timestamp}-{batch}.ndjson

Example: events/production/2026-04-14/1713091800-001.ndjson

Batching behavior

Mittr batches events before writing to reduce API calls:

Events accumulate in memory up to batchSize
A flush occurs when either:
- The batch reaches batchSize events
- flushIntervalSeconds has elapsed since the last flush
Each flush writes one object to storage

S3-compatible example (MinIO)

curl -X POST https://app.mittr.io/api/v1/endpoints \
  -H "X-API-Key: mtr_your_key" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "s3://local-archive/webhooks/",
    "deliveryMode": "storage",
    "eventTypes": ["*"],
    "storageConfig": {
      "provider": "s3",
      "bucket": "local-archive",
      "prefix": "webhooks/",
      "region": "us-east-1",
      "endpoint": "http://minio:9000",
      "accessKeyId": "minioadmin",
      "secretAccessKey": "minioadmin",
      "batchSize": 50,
      "flushIntervalSeconds": 30
    }
  }'

Security

Storage credentials are encrypted at rest in the database. They are never returned in API responses; only a masked indicator shows whether credentials are configured.