Destinations

​GCP Pub/Sub

Publish events to a Google Cloud Pub/Sub topic.

​Configuration

​Config

Field	Type	Required	Description
config.project_id	string	Yes	GCP project ID
config.topic	string	Yes	Pub/Sub topic name
config.endpoint	string	No	Custom endpoint (for emulator)

​Credentials

Field	Type	Required	Description
credentials.service_account_json	string	Yes*	Service account JSON key

*Not required when using the Pub/Sub emulator.

​Example

curl --location 'https://<OUTPOST_API_URL>/api/v1/<TENANT_ID>/destinations' \
--header 'Content-Type: application/json' \
--header 'Authorization: Bearer <API_KEY>' \
--data '{
  "type": "gcp_pubsub",
  "topics": ["orders"],
  "config": {
    "project_id": "my-project",
    "topic": "my-topic"
  },
  "credentials": {
    "service_account_json": "{\"type\": \"service_account\", ...}"
  }
}'
sh

​Message Format

Events are published as Pub/Sub messages with:

• Data: The event's data field (JSON)
• Attributes: Event metadata

​Example Message

If you publish an event:

{
  "topic": "orders",
  "data": {
    "order_id": "123",
    "status": "created"
  },
  "metadata": {
    "source": "checkout-service"
  }
}
json

Data:

{
  "order_id": "123",
  "status": "created"
}
json

Attributes:

Attributes include system metadata and any event metadata from the published event:

Attribute	Source	Description
event-id	System	The unique event ID
topic	System	The event topic
timestamp	System	Event timestamp (Unix)
*	Event	Any additional metadata from the published event's metadata field

​IAM Permissions

The service account needs the following role:

• roles/pubsub.publisher on the topic

Or the specific permission:

• pubsub.topics.publish

​Creating a Service Account

1. Navigate to IAM & Admin > Service Accounts in the GCP Console
2. Click Create Service Account
3. Grant the Pub/Sub Publisher role
4. Create a JSON key and download it
5. Use the JSON content as service_account_json

​Using with Emulator

For local development with the Pub/Sub emulator, set the config.endpoint field:

{
  "type": "gcp_pubsub",
  "topics": ["orders"],
  "config": {
    "project_id": "test-project",
    "topic": "test-topic",
    "endpoint": "localhost:8085"
  }
}
json

When using the emulator, service_account_json is not required.

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