Knative Eventing CloudEvents

asyncapi: 2.6.0
info:
  title: Knative Eventing CloudEvents
  description: >-
    Knative Eventing uses HTTP POST requests conforming to the CloudEvents
    specification to deliver events between event sources, Brokers, Triggers,
    Channels, and Subscriptions. Events can carry structured JSON data or
    binary payloads. This AsyncAPI document describes the CloudEvents message
    format and event types emitted by built-in Knative sources including
    ApiServerSource, PingSource, and generic Broker-routed events.
  version: '1.0'
  contact:
    name: Knative Community
    url: https://knative.dev/community/
externalDocs:
  description: Knative Eventing Documentation
  url: https://knative.dev/docs/eventing/
servers:
  broker:
    url: '{brokerURL}'
    protocol: http
    description: >-
      Knative Broker ingress URL. Events are sent via HTTP POST to the Broker
      address. The broker URL is available in the Broker resource's
      status.address.url field.
    variables:
      brokerURL:
        description: The URL of a Knative Broker ingress endpoint.
    security:
      - bearerAuth: []
  channel:
    url: '{channelURL}'
    protocol: http
    description: >-
      Knative Channel ingress URL. Events sent to this URL are fanned out to
      all Channel Subscriptions. The channel URL is available in the Channel
      resource's status.address.url field.
    variables:
      channelURL:
        description: The URL of a Knative Channel ingress endpoint.
    security:
      - bearerAuth: []
channels:
  /broker:
    description: >-
      CloudEvents are sent to Broker ingress via HTTP POST and delivered to
      all matching Triggers. Events must conform to the CloudEvents 1.0
      specification in either structured JSON or binary encoding.
    publish:
      operationId: sendEventToBroker
      summary: Send a CloudEvent to a Broker
      description: >-
        Publishes a CloudEvent to a Knative Broker. The Broker evaluates all
        associated Triggers and delivers the event to each Trigger whose
        attribute filters match the event's CloudEvent attributes.
      message:
        oneOf:
          - $ref: '#/components/messages/KubernetesApiEvent'
          - $ref: '#/components/messages/PingEvent'
          - $ref: '#/components/messages/GenericCloudEvent'
    subscribe:
      operationId: receiveEventFromBroker
      summary: Receive a CloudEvent from a Broker via Trigger
      description: >-
        A subscriber receives CloudEvents forwarded from a Broker via a Trigger.
        Events are delivered as HTTP POST requests to the subscriber's address
        in CloudEvents structured or binary format.
      message:
        oneOf:
          - $ref: '#/components/messages/KubernetesApiEvent'
          - $ref: '#/components/messages/PingEvent'
          - $ref: '#/components/messages/GenericCloudEvent'
  /channel:
    description: >-
      CloudEvents are sent to Channel ingress via HTTP POST and fanned out to
      all Subscriptions. Each Subscription receives the event independently.
    publish:
      operationId: sendEventToChannel
      summary: Send a CloudEvent to a Channel
      description: >-
        Publishes a CloudEvent to a Knative Channel. The Channel delivers the
        event to all associated Subscriptions independently.
      message:
        $ref: '#/components/messages/GenericCloudEvent'
    subscribe:
      operationId: receiveEventFromChannel
      summary: Receive a CloudEvent from a Channel via Subscription
      description: >-
        A subscriber receives CloudEvents forwarded from a Channel via a
        Subscription. Events are delivered as HTTP POST requests.
      message:
        $ref: '#/components/messages/GenericCloudEvent'
  /sink:
    description: >-
      Event sinks receive CloudEvents from sources like ApiServerSource,
      PingSource, and SinkBinding via HTTP POST. The sink URL is injected
      as K_SINK for SinkBinding subjects or specified in source specs.
    subscribe:
      operationId: receiveEventFromSource
      summary: Receive a CloudEvent from an event source
      description: >-
        An event sink receives CloudEvents from Knative event sources. Events
        from ApiServerSource carry Kubernetes API event data; PingSource events
        carry the configured payload; SinkBinding subjects send custom events.
      message:
        oneOf:
          - $ref: '#/components/messages/KubernetesApiEvent'
          - $ref: '#/components/messages/PingEvent'
          - $ref: '#/components/messages/GenericCloudEvent'
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: >-
        Kubernetes service account token for authenticating event delivery.
        Used when OIDC token-based authentication is enabled on Knative Eventing.
  messages:
    KubernetesApiEvent:
      name: KubernetesApiEvent
      title: Kubernetes API Server Event
      summary: >-
        A CloudEvent emitted by ApiServerSource when a Kubernetes resource
        event occurs (Added, Modified, or Deleted).
      contentType: application/json
      headers:
        type: object
        properties:
          ce-specversion:
            type: string
            const: '1.0'
            description: CloudEvents specification version.
          ce-type:
            type: string
            enum:
              - dev.knative.apiserver.resource.add
              - dev.knative.apiserver.resource.update
              - dev.knative.apiserver.resource.delete
              - dev.knative.apiserver.ref.add
              - dev.knative.apiserver.ref.update
              - dev.knative.apiserver.ref.delete
            description: >-
              CloudEvents type indicating the Kubernetes API event type.
              Resource modes include the full resource body; ref modes include
              only the resource reference.
          ce-source:
            type: string
            description: >-
              URI identifying the ApiServerSource that emitted this event,
              typically the Kubernetes API server URL.
          ce-id:
            type: string
            description: Unique identifier for this CloudEvent.
          ce-time:
            type: string
            format: date-time
            description: Timestamp when the event was created.
          ce-subject:
            type: string
            description: >-
              Subject identifying the Kubernetes resource that triggered the event,
              typically in the format namespace/name.
      payload:
        $ref: '#/components/schemas/KubernetesApiEventPayload'
    PingEvent:
      name: PingEvent
      title: PingSource Scheduled Event
      summary: >-
        A CloudEvent emitted by PingSource on a cron schedule with a
        configurable payload.
      contentType: application/json
      headers:
        type: object
        properties:
          ce-specversion:
            type: string
            const: '1.0'
            description: CloudEvents specification version.
          ce-type:
            type: string
            const: dev.knative.sources.ping
            description: CloudEvents type for PingSource events.
          ce-source:
            type: string
            description: >-
              URI identifying the PingSource, typically in the form
              /apis/v1/namespaces/{namespace}/pingsources/{name}.
          ce-id:
            type: string
            description: Unique identifier for this CloudEvent.
          ce-time:
            type: string
            format: date-time
            description: Timestamp when the ping event was fired.
      payload:
        $ref: '#/components/schemas/PingEventPayload'
    GenericCloudEvent:
      name: GenericCloudEvent
      title: Generic CloudEvent
      summary: >-
        A generic CloudEvent conforming to the CloudEvents 1.0 specification,
        used for custom event producers including SinkBinding subjects and
        custom event sources sending events through Brokers or Channels.
      contentType: application/json
      headers:
        type: object
        required:
          - ce-specversion
          - ce-type
          - ce-source
          - ce-id
        properties:
          ce-specversion:
            type: string
            const: '1.0'
            description: CloudEvents specification version. Must be 1.0.
          ce-type:
            type: string
            description: >-
              CloudEvents type attribute identifying the kind of event. Should
              be reverse-DNS formatted, for example com.example.order.created.
          ce-source:
            type: string
            description: >-
              URI identifying the context in which this event occurred,
              such as the system or service that produced the event.
          ce-id:
            type: string
            description: >-
              Unique identifier for this event within the scope of the source.
              Combined with source, must be globally unique.
          ce-time:
            type: string
            format: date-time
            description: Timestamp when the event occurred.
          ce-subject:
            type: string
            description: Subject of the event within the context of the source.
          ce-datacontenttype:
            type: string
            description: Content type of the data payload, typically application/json.
          ce-schemaurl:
            type: string
            format: uri
            description: URI identifying the schema for the event data.
      payload:
        type: object
        description: Arbitrary event payload. Structure depends on the event type.
  schemas:
    KubernetesApiEventPayload:
      type: object
      description: >-
        Payload of a Kubernetes API server event emitted by ApiServerSource.
        In Resource mode, contains the full Kubernetes resource object.
        In Reference mode, contains a reference to the affected resource.
      properties:
        apiVersion:
          type: string
          description: API version of the Kubernetes resource that triggered the event.
        kind:
          type: string
          description: Kind of the Kubernetes resource.
        metadata:
          type: object
          description: Kubernetes object metadata for the affected resource.
          properties:
            name:
              type: string
              description: Name of the resource.
            namespace:
              type: string
              description: Namespace of the resource.
            uid:
              type: string
              description: Unique identifier of the resource.
            resourceVersion:
              type: string
              description: Resource version at the time of the event.
            creationTimestamp:
              type: string
              format: date-time
              description: Time the resource was created.
        spec:
          type: object
          description: Spec of the Kubernetes resource (Resource mode only).
        status:
          type: object
          description: Status of the Kubernetes resource (Resource mode only).
    PingEventPayload:
      type: object
      description: >-
        Payload of a PingSource event. The content is the configured data
        field of the PingSource spec. Can be any valid JSON value.
      additionalProperties: true