List Lite subscriptions in topic

List Lite subscriptions in a Lite topic.

Explore further

For detailed documentation that includes this code sample, see the following:

• Create and manage Lite subscriptions

Code sample

Go

To authenticate to Pub/Sub Lite, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsublite"
	"google.golang.org/api/iterator"
)

func listSubscriptionsInTopic(w io.Writer, projectID, region, location, topicID string) error {
	// projectID := "my-project-id"
	// region := "us-central1"
	// NOTE: location can be either a region ("us-central1") or a zone ("us-central1-a")
	// For a list of valid locations, see https://cloud.google.com/pubsub/lite/docs/locations.
	// location := "us-central"
	// topicID := "my-topic"
	ctx := context.Background()
	client, err := pubsublite.NewAdminClient(ctx, region)
	if err != nil {
		return fmt.Errorf("pubsublite.NewAdminClient: %w", err)
	}
	defer client.Close()

	topicPath := fmt.Sprintf("projects/%s/locations/%s/topics/%s", projectID, location, topicID)
	subPathIter := client.TopicSubscriptions(ctx, topicPath)
	for {
		subPath, err := subPathIter.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			return fmt.Errorf("subPathIter.Next got err: %w", err)
		}
		fmt.Fprintf(w, "Got subscription: %s\n", subPath)
	}
	return nil
}

Java

To authenticate to Pub/Sub Lite, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import com.google.cloud.pubsublite.AdminClient;
import com.google.cloud.pubsublite.AdminClientSettings;
import com.google.cloud.pubsublite.CloudRegion;
import com.google.cloud.pubsublite.CloudRegionOrZone;
import com.google.cloud.pubsublite.CloudZone;
import com.google.cloud.pubsublite.ProjectNumber;
import com.google.cloud.pubsublite.SubscriptionPath;
import com.google.cloud.pubsublite.TopicName;
import com.google.cloud.pubsublite.TopicPath;
import java.util.List;

public class ListSubscriptionsInTopicExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String cloudRegion = "your-cloud-region";
    char zoneId = 'b';
    long projectNumber = Long.parseLong("123456789");
    String topicId = "your-topic-id";
    // True if using a regional location. False if using a zonal location.
    // https://cloud.google.com/pubsub/lite/docs/topics
    boolean regional = false;

    listSubscriptionsInTopicExample(cloudRegion, zoneId, projectNumber, topicId, regional);
  }

  public static void listSubscriptionsInTopicExample(
      String cloudRegion, char zoneId, long projectNumber, String topicId, boolean regional)
      throws Exception {

    CloudRegionOrZone location;
    if (regional) {
      location = CloudRegionOrZone.of(CloudRegion.of(cloudRegion));
    } else {
      location = CloudRegionOrZone.of(CloudZone.of(CloudRegion.of(cloudRegion), zoneId));
    }

    TopicPath topicPath =
        TopicPath.newBuilder()
            .setProject(ProjectNumber.of(projectNumber))
            .setLocation(location)
            .setName(TopicName.of(topicId))
            .build();

    AdminClientSettings adminClientSettings =
        AdminClientSettings.newBuilder().setRegion(CloudRegion.of(cloudRegion)).build();

    try (AdminClient adminClient = AdminClient.create(adminClientSettings)) {
      List<SubscriptionPath> subscriptionPaths =
          adminClient.listTopicSubscriptions(topicPath).get();
      for (SubscriptionPath subscription : subscriptionPaths) {
        System.out.println(subscription.toString());
      }
      if (regional) {
        System.out.println(
            subscriptionPaths.size()
                + " subscription(s) listed in the regional topic "
                + topicPath);
      } else {
        System.out.println(
            subscriptionPaths.size() + " subscription(s) listed in the zonal topic " + topicPath);
      }
    }
  }
}

Python

To authenticate to Pub/Sub Lite, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

from google.cloud.pubsublite import AdminClient
from google.cloud.pubsublite.types import CloudRegion, CloudZone, TopicPath

# TODO(developer):
# project_number = 1122334455
# cloud_region = "us-central1"
# zone_id = "a"
# topic_id = "your-topic-id"
# regional = True

if regional:
    location = CloudRegion(cloud_region)
else:
    location = CloudZone(CloudRegion(cloud_region), zone_id)

topic_path = TopicPath(project_number, location, topic_id)

client = AdminClient(cloud_region)
response = client.list_topic_subscriptions(topic_path)

for subscription_path in response:
    print(subscription_path)

print(f"{len(response)} subscription(s) listed in your topic.")

What's next

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