Webhook Payload

Payload format

Webhook actions send a POST request in CloudEvents 1.0 format. Each matched change produces a separate request.

{
  "specversion": "1.0",
  "type": "eventcatalog.governance.consumer_added",
  "source": "eventcatalog/governance",
  "id": "uuid",
  "time": "2026-03-04T12:00:00.000Z",
  "datacontenttype": "application/json",
  "data": {
    "schemaVersion": 1,
    "summary": "NotificationService is now consuming the event OrderConfirmed",
    "consumer": {
      "id": "NotificationService",
      "version": "0.0.2"
    },
    "message": {
      "id": "OrderConfirmed",
      "version": "0.0.1",
      "type": "event"
    }
  }
}

CloudEvents envelope

Field	Value
specversion	Always "1.0"
type	eventcatalog.governance.<trigger>, one of consumer_added, consumer_removed, producer_added, producer_removed, message_deprecated, schema_changed
source	eventcatalog/governance
id	Unique UUID per request
time	ISO 8601 timestamp
datacontenttype	application/json

Data object

Field	Description
schemaVersion	Always 1 (reserved for future format changes)
status	Only present when --status is passed to the CLI
summary	Human-readable description of the change
consumer or producer	The service involved. consumer for consumer triggers, producer for producer and message_deprecated triggers
message	The message involved, including its type (event, command, or query)
schema	Only present for schema_changed. Contains beforeHash, afterHash, beforePath, and afterPath
consumers	Only present for schema_changed. Array of services that consume the changed message
producers	Only present for schema_changed. Array of services that produce the changed message
refs	Only present for schema_changed. Contains base and target branch labels

Producer triggers

For producer_added and producer_removed, the consumer field is replaced with producer:

{
  "data": {
    "schemaVersion": 1,
    "summary": "OrdersService is now producing the event OrderCreated",
    "producer": {
      "id": "OrdersService",
      "version": "1.0.0"
    },
    "message": {
      "id": "OrderCreated",
      "version": "1.0.0",
      "type": "event"
    }
  }
}

Deprecation trigger

For message_deprecated, the payload identifies the producing service and the deprecated message. One webhook fires per producing service, so if a message has multiple producers, each producer sends a separate request.

{
  "specversion": "1.0",
  "type": "eventcatalog.governance.message_deprecated",
  "source": "eventcatalog/governance",
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "time": "2026-03-05T14:30:00.000Z",
  "datacontenttype": "application/json",
  "data": {
    "schemaVersion": 1,
    "summary": "OrderCreated (event) has been deprecated by OrdersService",
    "producer": {
      "id": "OrdersService",
      "version": "2.0.0",
      "owners": ["team-orders"]
    },
    "message": {
      "id": "OrderCreated",
      "version": "1.0.0",
      "type": "event"
    }
  }
}

The owners field is only present when the producing service has owners defined. The trigger fires only for newly deprecated messages: existing deprecations and un-deprecations do not fire.

Schema changed trigger

For schema_changed, the payload includes a schema object with hashes and paths for the before and after versions, plus arrays of the affected consumer and producer services. One webhook fires per changed message.

{
  "specversion": "1.0",
  "type": "eventcatalog.governance.schema_changed",
  "source": "eventcatalog/governance",
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "time": "2026-03-05T14:30:00.000Z",
  "datacontenttype": "application/json",
  "data": {
    "schemaVersion": 1,
    "summary": "Schema changed for event OrderCreated",
    "message": {
      "id": "OrderCreated",
      "version": "1.0.0",
      "type": "event"
    },
    "schema": {
      "beforeHash": "abc123",
      "afterHash": "def456",
      "beforePath": "schemas/order-created.v1.json",
      "afterPath": "schemas/order-created.v2.json"
    },
    "refs": {
      "base": "main",
      "target": "feature/update-schema"
    },
    "producers": [
      { "id": "OrdersService", "version": "1.0.0", "owners": ["team-orders"] }
    ],
    "consumers": [
      { "id": "PaymentService", "version": "1.0.0", "owners": ["team-payments"] }
    ]
  }
}

The schema.beforeHash and schema.afterHash are SHA-256 hashes of the schema file content. Either side can be null when a schema is first added or removed. The owners field on each service is only present when owners are defined.

Status field

When you pass --status to the CLI, the value is included in the payload. This is useful for distinguishing between stages in a pull request lifecycle.

eventcatalog governance check --status proposed

{
  "data": {
    "schemaVersion": 1,
    "status": "proposed",
    "summary": "NotificationService is now consuming the event OrderConfirmed",
    "consumer": { "id": "NotificationService", "version": "0.0.2" },
    "message": { "id": "OrderConfirmed", "version": "0.0.1", "type": "event" }
  }
}

Custom headers

Headers support environment variable substitution using $VAR_NAME syntax.

actions:
  - type: webhook
    url: $SLACK_WEBHOOK_URL
    headers:
      Authorization: Bearer $API_TOKEN
      X-Custom-Header: my-value