Backstage Events System

asyncapi: 3.0.0
info:
  title: Backstage Events System
  version: 1.0.0
  description: >-
    The Backstage Events system provides a publish-subscribe mechanism for
    broadcasting and consuming events within a Backstage instance. It enables
    plugins to emit events when significant actions occur (such as catalog
    entity changes, scaffolder task completions, or permission policy updates)
    and allows other plugins or external systems to subscribe to those events
    via HTTP webhooks or the internal event bus.
  contact:
    name: Backstage
    url: https://backstage.io
  license:
    name: Apache-2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
  externalDocs:
    description: Backstage Events Plugin Documentation
    url: https://backstage.io/docs/plugins/backends-and-plugins/
defaultContentType: application/json
channels:
  catalogEntityChange:
    address: backstage/catalog/entity
    description: >-
      Events emitted when catalog entities are created, updated, or deleted.
      These events are triggered by catalog processors and entity providers
      when the state of the software catalog changes.
    messages:
      catalogEntityChangeMessage:
        $ref: '#/components/messages/CatalogEntityChangeEvent'
  catalogLocationChange:
    address: backstage/catalog/location
    description: >-
      Events emitted when catalog locations are added, updated, or removed.
    messages:
      catalogLocationChangeMessage:
        $ref: '#/components/messages/CatalogLocationChangeEvent'
  scaffolderTaskComplete:
    address: backstage/scaffolder/task
    description: >-
      Events emitted when a scaffolder task changes status, including
      creation, completion, or failure.
    messages:
      scaffolderTaskCompleteMessage:
        $ref: '#/components/messages/ScaffolderTaskEvent'
  techdocsBuild:
    address: backstage/techdocs/build
    description: >-
      Events emitted when TechDocs documentation is built or updated.
    messages:
      techdocsBuildMessage:
        $ref: '#/components/messages/TechDocsBuildEvent'
operations:
  onCatalogEntityChange:
    action: receive
    channel:
      $ref: '#/channels/catalogEntityChange'
    summary: Receive catalog entity change events.
    description: >-
      Subscribe to notifications when catalog entities are created, updated,
      or deleted from the software catalog.
  onCatalogLocationChange:
    action: receive
    channel:
      $ref: '#/channels/catalogLocationChange'
    summary: Receive catalog location change events.
  onScaffolderTaskComplete:
    action: receive
    channel:
      $ref: '#/channels/scaffolderTaskComplete'
    summary: Receive scaffolder task lifecycle events.
  onTechDocsBuild:
    action: receive
    channel:
      $ref: '#/channels/techdocsBuild'
    summary: Receive TechDocs build events.
components:
  messages:
    CatalogEntityChangeEvent:
      name: CatalogEntityChangeEvent
      title: Catalog Entity Change Event
      contentType: application/json
      payload:
        type: object
        required:
          - topic
          - eventPayload
          - metadata
        properties:
          topic:
            type: string
            const: catalog
            description: The event topic.
          eventPayload:
            type: object
            required:
              - action
              - entity
            properties:
              action:
                type: string
                enum:
                  - created
                  - updated
                  - deleted
                description: The action that occurred.
              entity:
                type: object
                properties:
                  apiVersion:
                    type: string
                  kind:
                    type: string
                  metadata:
                    type: object
                    properties:
                      name:
                        type: string
                      namespace:
                        type: string
                      uid:
                        type: string
                description: The affected catalog entity.
          metadata:
            $ref: '#/components/schemas/EventMetadata'
    CatalogLocationChangeEvent:
      name: CatalogLocationChangeEvent
      title: Catalog Location Change Event
      contentType: application/json
      payload:
        type: object
        required:
          - topic
          - eventPayload
          - metadata
        properties:
          topic:
            type: string
            const: catalog
          eventPayload:
            type: object
            properties:
              action:
                type: string
                enum:
                  - added
                  - updated
                  - removed
              location:
                type: object
                properties:
                  type:
                    type: string
                  target:
                    type: string
          metadata:
            $ref: '#/components/schemas/EventMetadata'
    ScaffolderTaskEvent:
      name: ScaffolderTaskEvent
      title: Scaffolder Task Event
      contentType: application/json
      payload:
        type: object
        required:
          - topic
          - eventPayload
          - metadata
        properties:
          topic:
            type: string
            const: scaffolder
          eventPayload:
            type: object
            properties:
              action:
                type: string
                enum:
                  - created
                  - processing
                  - completed
                  - failed
                  - cancelled
              taskId:
                type: string
              templateRef:
                type: string
                description: >-
                  Entity reference of the template used
                  (e.g., template:default/create-react-app).
              createdBy:
                type: string
                description: Entity reference of the user who created the task.
          metadata:
            $ref: '#/components/schemas/EventMetadata'
    TechDocsBuildEvent:
      name: TechDocsBuildEvent
      title: TechDocs Build Event
      contentType: application/json
      payload:
        type: object
        required:
          - topic
          - eventPayload
          - metadata
        properties:
          topic:
            type: string
            const: techdocs
          eventPayload:
            type: object
            properties:
              action:
                type: string
                enum:
                  - build_started
                  - build_completed
                  - build_failed
              entityRef:
                type: string
                description: >-
                  Entity reference for the documented entity
                  (e.g., component:default/my-service).
              buildTimestamp:
                type: string
                format: date-time
          metadata:
            $ref: '#/components/schemas/EventMetadata'
  schemas:
    EventMetadata:
      type: object
      properties:
        source:
          type: string
          description: The source plugin or system that emitted the event.
        eventId:
          type: string
          format: uuid
          description: Unique identifier for this event.
        timestamp:
          type: string
          format: date-time
          description: ISO 8601 timestamp of when the event was emitted.
        correlationId:
          type: string
          description: Correlation ID for tracing related events.