workflows-pubsub

Workflows and Eventarc Pub/Sub Integration

In this sample, you will see how to connect Workflows to Eventarc.

More specifically, you will see how Workflows can send a Pub/Sub message to a topic that triggers a Cloud Run service via Eventarc.

Deploy a Cloud Run service to receive events

First, deploy a Cloud Run service to receive events from Eventarc.

Set some vars:

export SERVICE_NAME=hello
export REGION=us-central1
export GOOGLE_CLOUD_PROJECT=$(gcloud config get-value project)
gcloud config set run/region ${REGION}
gcloud config set run/platform managed

Deploy to Cloud Run:

gcloud run deploy ${SERVICE_NAME} \
  --image gcr.io/cloudrun/hello \
  --allow-unauthenticated

Create and connect a Pub/Sub topic to the Cloud Run service

Create a Pub/Sub topic to use between Workflows and Eventarc + Cloud Run:

export TOPIC_ID=workflows-to-eventarc-topic
gcloud pubsub topics create workflows-to-eventarc-topic

Connect the Pub/Sub topic to the Cloud Run service by creating an Eventarc Pub/Sub trigger:

gcloud config set eventarc/location ${REGION}
gcloud eventarc triggers create ${SERVICE_NAME}-trigger \
  --destination-run-service=${SERVICE_NAME} \
  --destination-run-region=${REGION} \
  --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
  --transport-topic=projects/${GOOGLE_CLOUD_PROJECT}/topics/${TOPIC_ID}

Define workflow

Create a workflow.yaml to define the workflow. It simply publishes a Pub/Sub message to the workflows-to-eventarc-topic topic:

- init:
    assign:
      - project: ${sys.get_env("GOOGLE_CLOUD_PROJECT_ID")}
      - topic: "workflows-to-eventarc-topic"
      - message: "Hello world!"
- publish:
    call: googleapis.pubsub.v1.projects.topics.publish
    args:
      topic: ${"projects/" + project + "/topics/" + topic}
      body:
        messages:
          - data: ${base64.encode(text.encode(message))}
    result: publish_result
- last:
    return: ${publish_result}

Deploy and execute workflow

Deploy the workflow:

gcloud workflows deploy workflows-to-eventarc \
    --source=workflow.yaml

Execute workflow:

gcloud workflows execute workflows-to-eventarc

After a few seconds, you should see the Hello World Pub/Sub message received by the Cloud Run service via Eventarc:

gcloud logging read "resource.type=cloud_run_revision AND resource.labels.service_name=${SERVICE_NAME}" \
    | grep "Hello world"