CloudEvents - JSON event format

CloudEvents (cloudevents.io) is a specification for describing event data in a common way. The specification is under the Cloud Native Computing Foundation (CNCF) and is organized by the CNCF's Serverless Working Group.

Eventarc delivers events to the event receiver in the CloudEvents format through an HTTP request. The destination target—for example, the Workflows service—converts the event to a JSON object (following the CloudEvents specification) and passes the event into the workflow execution as a workflow runtime argument.

JSON payload format

The destination service receives events from event routers and formats the events to the JSON Event Format for CloudEvents version 1.0.1 with the following CloudEvents attributes:

Attribute Description Example
data The payload of the event data.
{
  "subscription": "projects/my-project/subscriptions/my-sub",
  "message": {
    "attributes": {
      "attr1":"attr1-value"
    },
    "data": "aGVsbG8gd29ybGQ=",
    "messageId": "2070443601311540",
    "publishTime":"2021-02-26T19:13:55.749Z"
  }
}
datacontenttype The type of data that has been passed application/json
id The unique identifier for the event 2070443601311540
source The source of the event //pubsub.googleapis.com/projects/my-project/topics/my-topic
specversion The CloudEvents specification version used for this event 1.0
type The type of event data google.cloud.pubsub.topic.v1.messagePublished
time Event generation time, in RFC 3339 format (optional) 2020-12-20T13:37:33.647Z

Depending on the event type, the payload format is as follows:

Cloud Audit Logs

The runtime argument is a JSON object detailing the Cloud Audit Logs event. In this document, see the Common events example. In the JSON object, you can find the resourceName, serviceName, and methodName values. For more information, see Determine event filters for Cloud Audit Logs.

Events of type google.cloud.audit.log.v1.written have the following format:

{
  "data":{ EVENT_DATA }
  "datacontenttype": "application/json; charset=utf-8",
  "id": "MESSAGE_ID",
  "source": "//cloudaudit.googleapis.com/projects/PROJECT_ID/logs/data_access",
  "specversion": "1.0",
  "type": "google.cloud.audit.log.v1.written",
  "time": "EVENT_GENERATION_TIME",
  "dataschema": "https://googleapis.github.io/google-cloudevents/jsonschema/google/events/cloud/audit/v1/LogEntryData.json",
  "methodName": "jobservice.jobcompleted",
  "resourceName": "projects/my-project/jobs/bqjob_r3ac45813612fa2d6_0000017d591922c9_1",
  "serviceName": "bigquery.googleapis.com",
  "subject": "bigquery.googleapis.com/projects/my-project/jobs/bqjob_r3ac45813612fa2d6_0000017d591922c9_1",
}
  • EVENT_DATA: the decoded message content in JSON format. For more information, in this document, see Common events.
  • MESSAGE_ID, EVENT_GENERATION_TIME: system-generated.
  • PROJECT_ID: your GCP project ID.
  • dataschema, methodName, resourceName, serviceName, subject: attributes specific to the event type.

Cloud Storage

The runtime arguments are changes to Cloud Storage. In the data field you can find the change in the Cloud Storage bucket. In this document, see the Common events example.

Events of type google.cloud.storage.object.v1.finalized have the following format:

{
  "data":{ EVENT_DATA },
  "datacontenttype": "application/json",
  "id": "MESSAGE_ID",
  "source": "//storage.googleapis.com/projects/_/buckets/BUCKET_NAME",
  "specversion": "1.0",
  "type": "google.cloud.storage.object.v1.finalized",
  "time": "EVENT_GENERATION_TIME",
  "subject": "objects/my-file.txt",
}
  • EVENT_DATA: the decoded message content in JSON format. For more information, in this document, see Common events.
  • MESSAGE_ID, EVENT_GENERATION_TIME: system-generated.
  • BUCKET_NAME: the name of the Cloud Storage bucket that gets updated.
  • subject: attribute specific to the event type.

Pub/Sub

The runtime argument is a Pub/Sub push message. In the data field you can find the message as a Base64-encoded string. In this document, see the Common events example.

Events of type google.cloud.pubsub.topic.v1.messagePublished have the following format:

{
  "data":{ EVENT_DATA },
  "datacontenttype": "application/json; charset=utf-8",
  "id": "MESSAGE_ID",
  "source": "//pubsub.googleapis.com/TOPIC_NAME",
  "specversion": "1.0",
  "type": "google.cloud.pubsub.topic.v1.messagePublished",
  "time": "EVENT_GENERATION_TIME",
}
  • EVENT_DATA: the decoded message content in JSON format. For more information, in this document, see Common events.
  • MESSAGE_ID, EVENT_GENERATION_TIME: system-generated.
  • TOPIC_NAME: the Pub/Sub topic name to which the event was published to.

Common events

Protocol Buffers (or protobufs) represent the data within events that are generated by Eventarc. Protocol Buffers for CloudEvents are provided as machine-readable schemas, allowing libraries of data types to be created and making it easier to consume events.

There are two protobuf messages that are relevant for any given CloudEvent type:

  • The envelope message that represents the complete CloudEvent, including any extension attributes; for example, AuditLogWrittenEvent.
  • The data message; for example, LogEntryData or StorageObjectData.
Many CloudEvent types can use the same data message. For example, every event associated with a Cloud Storage object uses StorageObjectData as the data message. Each envelope message specifies the CloudEvent type that it is associated with through a proto annotation. For more information, see Relationship between protobuf messages and CloudEvent types.

The following tables detail the components of some common events:

Cloud Audit Logs

Proto filesgoogle/events/cloud/audit/v1/events.proto
google/events/cloud/audit/v1/data.proto
Envelope messagegoogle.events.cloud.audit.v1.AuditLogWrittenEvent
Data messagegoogle.events.cloud.audit.v1.LogEntryData
Event type
(when an audit log entry is written)
google.cloud.audit.log.v1.written
Event extensions
  • serviceName
  • methodName
  • resourceName
Example Pub/Sub audit log
BigQuery audit log

Cloud Storage

Proto files google/events/cloud/storage/v1/events.proto
google/events/cloud/storage/v1/data.proto
Envelope messagesgoogle.events.cloud.storage.v1.ObjectFinalizedEvent
google.events.cloud.storage.v1.ObjectArchivedEvent
google.events.cloud.storage.v1.ObjectDeletedEvent
google.events.cloud.storage.v1.ObjectMetadataUpdatedEvent
Data messagegoogle.events.cloud.storage.v1.StorageObjectData
Resource Objects
Event types
(when a Cloud Storage job is finalized, archived, deleted, updated)
google.cloud.storage.object.v1.finalized
google.cloud.storage.object.v1.archived
google.cloud.storage.object.v1.deleted
google.cloud.storage.object.v1.metadataUpdated
Examples Simple
Complex

Pub/Sub

Proto files google/events/cloud/pubsub/v1/events.proto
google/events/cloud/pubsub/v1/data.proto
Envelope messagegoogle.events.cloud.pubsub.v1.MessagePublishedEvent
Data messagegoogle.events.cloud.pubusb.v1.MessagePublishedData
Resource PubsubMessage
Event type
(when a Pub/Sub message is published)
google.cloud.pubsub.topic.v1.messagePublished
Examples Text