Pubsublite subscription dead letter topic set remediation

Triage and Remediation

Remediation

Using Console

Using CLI

To remediate the misconfiguration of PubSub Lite Subscription not having a Dead Letter Queue in GCP, you can follow the below steps using GCP CLI:

Open the Cloud Shell in the GCP Console.
Set the environment variables for your GCP project ID and the name of the PubSub Lite subscription that you want to remediate. Replace [PROJECT_ID] and [SUBSCRIPTION_NAME] with your actual project ID and subscription name.

export PROJECT_ID=[PROJECT_ID]
export SUBSCRIPTION_NAME=[SUBSCRIPTION_NAME]

Create a Dead Letter Topic for the subscription using the following gcloud command. Replace [DEAD_LETTER_TOPIC_NAME] with the name of the topic that you want to create.

gcloud pubsub topics create [DEAD_LETTER_TOPIC_NAME] --project=$PROJECT_ID

Grant the Pub/Sub service account permission to publish messages to the Dead Letter Topic using the following gcloud command.

gcloud projects add-iam-policy-binding $PROJECT_ID --member=serviceAccount:[email protected] --role=roles/pubsub.publisher

Update the subscription to set the Dead Letter Policy using the following gcloud command. Replace [DEAD_LETTER_TOPIC_NAME] with the name of the topic that you created in step 3.

gcloud pubsub lite-subscriptions update $SUBSCRIPTION_NAME --project=$PROJECT_ID --dead-letter-topic=projects/$PROJECT_ID/topics/[DEAD_LETTER_TOPIC_NAME]

Verify that the Dead Letter Policy has been set for the subscription using the following gcloud command.

gcloud pubsub lite-subscriptions describe $SUBSCRIPTION_NAME --project=$PROJECT_ID

You can also verify that the Dead Letter Topic has been created and that the Pub/Sub service account has been granted permission to publish messages to it using the following gcloud commands.

gcloud pubsub topics describe [DEAD_LETTER_TOPIC_NAME] --project=$PROJECT_ID

gcloud projects get-iam-policy $PROJECT_ID --flatten="bindings[].members" --format='table(bindings.role)' --filter="bindings.members:[email protected]"

After following these steps, the PubSub Lite Subscription would have a Dead Letter Queue configured, and messages that cannot be delivered to the original subscriber will be redirected to the Dead Letter Topic for further analysis and processing.

Using Python

To remediate the misconfiguration of PubSub Lite Subscription should have a Dead Letter Queue in GCP using Python, follow the steps below:

First, you need to create a Dead Letter Topic. You can use the following code to create a Dead Letter Topic:

from google.cloud import pubsub_v1

project_id = "your-project-id"
dead_letter_topic_id = "dead-letter-topic"

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path(project_id, dead_letter_topic_id)

try:
    topic = publisher.create_topic(request={"name": topic_path})
    print(f"Topic created: {topic.name}")
except Exception as e:
    print(f"Error creating topic: {e}")

Once the Dead Letter Topic is created, you can create a subscription with the Dead Letter Topic attached to it. You can use the following code to create a subscription:

from google.cloud import pubsub_v1

project_id = "your-project-id"
subscription_id = "your-subscription-id"
topic_id = "your-topic-id"
dead_letter_topic_id = "dead-letter-topic"

subscriber = pubsub_v1.SubscriberClient()
subscription_path = subscriber.subscription_path(project_id, subscription_id)
topic_path = subscriber.topic_path(project_id, topic_id)
dead_letter_topic_path = subscriber.topic_path(project_id, dead_letter_topic_id)

push_config = pubsub_v1.types.PushConfig(dead_letter_topic=dead_letter_topic_path)

try:
    subscription = subscriber.create_subscription(
        request={"name": subscription_path, "topic": topic_path, "push_config": push_config}
    )
    print(f"Subscription created: {subscription.name}")
except Exception as e:
    print(f"Error creating subscription: {e}")

Now, you can test the subscription by publishing a message to the topic and checking if the message is delivered to the Dead Letter Topic. You can use the following code to publish a message:

from google.cloud import pubsub_v1

project_id = "your-project-id"
topic_id = "your-topic-id"

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path(project_id, topic_id)

message = b"Test message"
try:
    future = publisher.publish(topic_path, message)
    print(f"Message published: {future.result()}")
except Exception as e:
    print(f"Error publishing message: {e}")

Check the Dead Letter Topic to confirm that the message was delivered there. You can use the following code to check the messages in the Dead Letter Topic:

from google.cloud import pubsub_v1

project_id = "your-project-id"
dead_letter_topic_id = "dead-letter-topic"

subscriber = pubsub_v1.SubscriberClient()
dead_letter_topic_path = subscriber.topic_path(project_id, dead_letter_topic_id)

def callback(message):
    print(f"Received message: {message.data}")
    message.ack()

subscription_path = subscriber.subscription_path(project_id, subscription_id)
subscriber.subscribe(subscription_path, callback=callback)

print(f"Listening for messages on {subscription_path}...\n")
while True:
    try:
        subscriber.consume(dead_letter_topic_path, timeout=10)
    except Exception as e:
        print(f"Error consuming messages: {e}")

By following these steps, you can remediate the misconfiguration of PubSub Lite Subscription should have a Dead Letter Queue in GCP using Python.

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Pubsublite subscription dead letter topic set remediation

Triage and Remediation

Remediation

GCP Introduction

GCP Pricing

GCP Threats

GCP Misconfigurations

Resources

GCP Threats

​Triage and Remediation

​Remediation

Triage and Remediation

Remediation