README.md

PullSubscription Example

This sample shows how to configure PullSubscriptions, which is our Kubernetes object to represent Cloud Pub/Sub subscriptions. This resource can be considered an implementation detail of the CloudPubSubSource, and users should rather use the latter if they want to bridge events from Pub/Sub into their clusters. As opposed to the
CloudPubSubSource, which sends events using the Push-compatible format, this does so using a Pull format.

Prerequisites

1. Install Knative-GCP

2. Create a Pub/Sub enabled Service Account

Deployment

1. Create a Cloud Pub/Sub Topic.

   export TOPIC_NAME=testing
   gcloud pubsub topics create $TOPIC_NAME

2. Update googleServiceAccount / secret in the pullsubscription.yaml

   1. If you are in GKE and using Workload Identity, update googleServiceAccount with the Pub/Sub enabled service account you created in Create a Pub/Sub enabled Service Account.

   2. If you are using standard Kubernetes secrets, but want to use a non-default one, update secret with your own secret.

3. Update TOPIC_NAME in the pullsubscription.yaml and apply it.

   If you're in the pullsubscription directory, you can replace TOPIC_NAME and apply in one command:

   sed "s/\TOPIC_NAME/$TOPIC_NAME/g" pullsubscription.yaml | \
       kubectl apply --filename -

   If you are replacing TOPIC_NAME manually, then make sure you apply the resulting YAML:

   kubectl apply --filename pullsubscription.yaml

4. [Optional] If you are not using GKE, or want to use a Pub/Sub topic from another project, uncomment and replace the MY_PROJECT placeholder in pullsubscription.yaml and apply it. Note that the Service Account during the installation step should be able to manage multiple projects.

   If you're in the pullsubscription directory, you can replace MY_PROJECT and TOPIC_NAME and then apply in one command:

   sed "s/\TOPIC_NAME/$TOPIC_NAME/g" pullsubscription.yaml | \
   sed "s/\#project: MY_PROJECT/project: $PROJECT_ID/g" | \
       kubectl apply --filename -

   If you are replacing MY_PROJECT manually, then make sure you apply the resulting YAML:

   kubectl apply --filename pullsubscription.yaml

5. Create a Service that the PullSubscription will sink into:

   kubectl apply --filename event-display.yaml

Publish

Publish messages to your Cloud Pub/Sub Topic:

gcloud pubsub topics publish testing --message='{"Hello": "world"}'

Verify

We will verify that the published message was sent by looking at the logs of the service that this PullSubscription sinks to.

1. We need to wait for the downstream pods to get started and receive our event, wait 60 seconds.

   • You can check the status of the downstream pods with:

     kubectl get pods --selector app=event-display

     You should see at least one.

2. Inspect the logs of the service:

   kubectl logs --selector app=event-display -c user-container

You should see log lines similar to:

☁️ cloudevents.Event
Validation: valid
 Context Attributes,
   specversion: 1.0
   type: com.google.cloud.pubsub.topic.publish
   source: //pubsub.googleapis.com/PROJECT_ID/topics/TOPIC_NAME
   id: 9f9b0968-a15f-4e74-ac58-e8a1c4fa587d
   time: 2019-06-10T17:52:36.73Z
   contenttype: application/octet-stream
 Data,
   {
     "Hello": "world"
   }

For more information about the format of the Data see the data field of PubsubMessage documentation.

What's next

1. For more details on Cloud Pub/Sub formats refer to the Subscriber overview guide.
2. For a higher-level construct to interact with Cloud Pub/Sub that sends Push-compatible format events, see the PubSub example.
3. For integrating with Cloud Storage see the Storage example.
4. For integrating with Cloud Scheduler see the Scheduler example.
5. For integrating with Cloud Audit Logs see the Cloud Audit Logs example.
6. For more information about CloudEvents, see the HTTP transport bindings documentation.

Cleaning Up

1. Delete the PullSubscription

   If you're in the pullsubscription directory, you can replace TOPIC_NAME and delete in one command:

    sed "s/\TOPIC_NAME/$TOPIC_NAME/g" pullsubscription.yaml | \
        kubectl delete --filename -

   If you replaced TOPIC_NAME manually, then make sure you delete the resulting YAML:

   kubectl delete --filename pullsubscription.yaml

2. Delete the Service used as the sink:

   kubectl delete --filename event-display.yaml