Eventarc

Eventarc is Google Cloud's unified eventing platform. It provides a standardised way to receive, route, and deliver events from Google Cloud services, custom applications, and third-party SaaS products to event consumers such as Cloud Run, Cloud Functions (Gen 2), GKE, and Workflows.

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What Is Eventarc?

Eventarc allows you to build event-driven architectures without managing messaging infrastructure. You create triggers that define which events to listen for and where to deliver them. Eventarc handles the routing, delivery, retry logic, and dead-lettering.

Key Concepts

Concept	Description
Event	A structured notification that something has happened (e.g., a file uploaded, a VM created)
Event provider	The source that produces events (Cloud Storage, BigQuery, custom app)
Trigger	A rule that matches events and routes them to a destination
Destination	The target that receives the event (Cloud Run, Cloud Functions, GKE, Workflows)
Channel	A resource that transports events (used for custom and third-party events)

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Event Formats: CloudEvents

Eventarc uses the CloudEvents specification (CNCF standard) for all events. CloudEvents provides a consistent, vendor-neutral envelope for event data, making events portable across platforms.

CloudEvents Attributes

Attribute	Description	Example
id	Unique event identifier	"abc123"
source	Event origin	"//storage.googleapis.com/projects/my-project/buckets/my-bucket"
type	Event type	"google.cloud.storage.object.v1.finalized"
time	Timestamp	"2025-01-15T10:30:00Z"
subject	Event subject	"objects/my-file.pdf"
data	Event payload	(JSON object with event details)

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Event Sources

Eventarc supports three categories of event sources:

1. Direct Events

Direct events come from Google Cloud services that natively integrate with Eventarc. These are delivered with low latency and high reliability.

Service	Event Types
Cloud Storage	Object finalized, deleted, archived, metadata updated
BigQuery	Job completed, table created, dataset updated
Pub/Sub	Messages published to a topic
Firestore	Document created, updated, deleted
Firebase	User created, deleted

2. Audit Log Events

Any Google Cloud API call that generates a Cloud Audit Log entry can trigger an Eventarc event. This provides coverage of over 130 Google Cloud services without requiring those services to natively integrate with Eventarc.