CloudEvents - JSON event format

Advanced Standard

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 Google Cloud 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.

Open source repository

The structure of the HTTP body for all events are available on the CloudEvents GitHub repository.

The repository contains the following to help you understand and use CloudEvents data in your programming language:

Google Protocol Buffers for CloudEvents data payloads
Generated JSON schemas
A public JSON schema catalog

Links to client libraries are also included.

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 files	google/events/cloud/audit/v1/events.proto google/events/cloud/audit/v1/data.proto
Envelope message	`google.events.cloud.audit.v1.AuditLogWrittenEvent`
Data message	`google.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` See the list of event types using Cloud Audit Logs.
Examples	Pub/Sub audit log BigQuery audit log
More information	Create an Eventarc trigger for a Cloud Audit Logs event Determine event filters for Cloud Audit Logs Google Cloud services with audit logs

Cloud Storage

Proto files	google/events/cloud/storage/v1/events.proto google/events/cloud/storage/v1/data.proto
Envelope messages	`google.events.cloud.storage.v1.ObjectFinalizedEvent` `google.events.cloud.storage.v1.ObjectArchivedEvent` `google.events.cloud.storage.v1.ObjectDeletedEvent` `google.events.cloud.storage.v1.ObjectMetadataUpdatedEvent`
Data message	`google.events.cloud.storage.v1.StorageObjectData`
Resource	`Objects`
Event types	See the list of direct event types.
Examples	Simple Complex
More information	Create an Eventarc trigger for a Cloud Storage event Receive events from Cloud Storage in a Cloud Run service

Firestore

Proto files	google/events/cloud/firestore/v1/events.proto google/events/cloud/firestore/v1/data.proto
Envelope messages	`google.events.cloud.firestore.v1.DocumentCreatedEvent` `google.events.cloud.firestore.v1.DocumentUpdatedEvent` `google.events.cloud.firestore.v1.DocumentDeletedEvent` `google.events.cloud.firestore.v1.DocumentWrittenEvent`
Data message	`google.events.cloud.firestore.v1.DocumentEventData`
Resource	`Document`
Event types	See the list of direct event types.
Examples	Simple Complex
More information	Create an Eventarc trigger for a Firestore event Create event-driven architectures with Eventarc and Firestore Extend with Cloud Run functions to handle events triggered by changes in Firestore

Pub/Sub

Proto files	google/events/cloud/pubsub/v1/events.proto google/events/cloud/pubsub/v1/data.proto
Envelope message	`google.events.cloud.pubsub.v1.MessagePublishedEvent`
Data message	`google.events.cloud.pubsub.v1.MessagePublishedData`
Resource	`PubsubMessage`
Event type (when a Pub/Sub message is published)	`google.cloud.pubsub.topic.v1.messagePublished`
Example	Text
More information	Receive events in a Cloud Run service using Pub/Sub messages Trigger a workflow using Pub/Sub messages