Microsoft Azure Event Grid Webhooks

generated: '2026-09-06'
method: searched
source: >-
  https://learn.microsoft.com/en-us/azure/event-grid/system-topics (HTTP 200),
  https://learn.microsoft.com/en-us/azure/event-grid/event-schema (HTTP 200),
  https://learn.microsoft.com/en-us/azure/event-grid/cloud-event-schema (HTTP 200) and
  https://learn.microsoft.com/en-us/azure/event-grid/webhook-event-delivery (HTTP 200) — all read
  2026-09-06.
provider: Microsoft Azure Cloud
providerId: azure-cloud
asyncapi_spec:
  published: false
  searched:
    - https://github.com/Azure/azure-rest-api-specs (specification/eventgrid/)
    - https://azure.microsoft.com/llms.txt
    - Event Grid documentation
  finding: >-
    Azure publishes NO AsyncAPI document for any of its event surfaces. It publishes event payload
    schemas — as JSON Schema fragments inside the Event Grid data-plane specs in
    Azure/azure-rest-api-specs, and as prose tables per publisher on Learn — but nothing that describes
    the channels, bindings and operations the way AsyncAPI does. Recorded as an honest absence, not
    fabricated.
webhooks:
  mechanism: Azure Event Grid
  docs: https://learn.microsoft.com/en-us/azure/event-grid/
  transport: HTTPS POST to a subscriber-supplied endpoint
  schemas:
    - name: CloudEvents v1.0 (JSON)
      standard: true
      spec: https://github.com/cloudevents/spec/blob/v1.0/json-format.md
      binding: https://github.com/cloudevents/spec/blob/v1.0/http-protocol-binding.md
      docs: https://learn.microsoft.com/en-us/azure/event-grid/cloud-event-schema
      note: >-
        Native support. Microsoft is a listed collaborator on the CNCF CloudEvents specification. This
        is the schema to prefer — it is the interoperable one.
    - name: Event Grid event schema
      standard: false
      docs: https://learn.microsoft.com/en-us/azure/event-grid/event-schema
      note: Azure's own proprietary envelope, predating the CloudEvents support.
  endpoint_validation:
    cloudevents:
      method: HTTP OPTIONS
      mechanism: >-
        CloudEvents v1.0 abuse-protection handshake. Event Grid sends an OPTIONS request carrying
        WebHook-Request-Origin; the subscriber must answer with WebHook-Allowed-Origin. When the
        CloudEvents schema is selected this REPLACES the Event Grid validation event.
      docs: https://learn.microsoft.com/en-us/azure/event-grid/webhook-event-delivery
      caveat: >-
        Microsoft is explicit that the handshake "doesn't aim to establish an authentication or
        authorization context. It only serves to protect the sender from being told to push to a
        destination that isn't expecting the traffic." A subscriber must still authorize the delivery
        itself.
    event_grid_schema:
      method: SubscriptionValidationEvent
      mechanism: >-
        Event Grid POSTs a validation event with a validationCode the subscriber must echo back, or
        alternatively a validationUrl that can be visited once manually.
  delivery:
    retry: Exponential backoff with a configurable retry policy and event time-to-live.
    dead_lettering: Undeliverable events can be routed to a storage account.
    ordering: Not guaranteed.
    delivery_semantics: at-least-once
    note: >-
      At-least-once delivery with no ordering guarantee means a subscriber MUST be idempotent on its own
      side. That obligation sits with the subscriber, and Azure documents it rather than solving it —
      which is consistent with the absence of any idempotency mechanism on the request side (see
      conventions/azure-cloud-conventions.yml#idempotency).
  destinations:
    - Webhook (HTTPS endpoint)
    - Azure Functions
    - Event Hubs
    - Service Bus queue or topic
    - Storage queue
    - Relay hybrid connection
    - Azure Automation runbook
publishers:
  note: >-
    Azure services that emit events to an Event Grid system topic, listed verbatim from
    https://learn.microsoft.com/en-us/azure/event-grid/system-topics on 2026-09-06. Each links to its own
    event-schema page giving the event types and payload shape.
  count: 26
  sources:
    - Azure API Center
    - Azure API Management
    - Azure App Configuration
    - Azure App Service
    - Azure Blob Storage
    - Azure Cache for Redis
    - Azure Communication Services
    - Azure Container Registry
    - Azure Data Box
    - Azure Event Grid
    - Azure Event Hubs
    - Azure Health Data Services
    - Azure IoT Hub
    - Azure Key Vault
    - Azure Kubernetes Service
    - Azure Machine Learning
    - Azure Maintenance Configuration
    - Azure Maps
    - Azure Media Services
    - Azure Policy
    - Azure Resource Notifications
    - Azure resource groups
    - Azure Service Bus
    - Azure SignalR
    - Azure Storage Actions
    - Azure subscriptions
management_contract:
  note: >-
    Event Grid topics, system topics and event subscriptions are themselves ARM resources, so the
    subscription lifecycle is a REST surface. The Event Grid resource provider spec was not harvested in
    this pass; the Service Bus contract in openapi/azure-cloud-service-bus-api-openapi.json is the
    closest messaging contract in this repo.
  reference: https://learn.microsoft.com/en-us/rest/api/eventgrid/
other_event_surfaces:
  - name: Azure Service Bus
    kind: message-broker
    protocol: AMQP 1.0
    contract: openapi/azure-cloud-service-bus-api-openapi.json
    note: Queues, topics and subscriptions as ARM resources; the data plane is AMQP, not HTTP webhooks.
  - name: Azure Event Hubs
    kind: streaming
    protocol: AMQP 1.0 / Kafka protocol
    note: Not harvested in this pass.
  - name: Azure Web PubSub / SignalR
    kind: websocket
    note: Not harvested in this pass.