script to discover the dead pubsub subscriptions

[anaskhandevops]

Hi there, I am currently facing an issue while attempting to discover dead subscriptions in Google Cloud Pub/Sub using Node.js scripts.

Background: I recently set up an alert system on a Pub/Sub topic to send a notification to Slack if the backlog ever exceeds 50 messages. However, I encountered a situation where the message backlog reached over 200K messages. To address this, I am now trying to create a script that can identify and clean up dead Pub/Sub subscriptions.

Issue: While I am not very familiar with Node.js, I attempted to create a scripts using the @google-cloud/pubsub library. Unfortunately, neither of these scripts seems to be working as expected.

script:

const { PubSub } = require('@google-cloud/pubsub'); 

// Replace 'your-project-id' with your actual Google Cloud Project ID 
const projectId = 'your-project-id'; 

// Creates a PubSub client 
const pubsub = new PubSub({ projectId }); 

async function discoverDeadSubscriptions() { 
 try { 
   // List all subscriptions in the project 
   const [subscriptions] = await pubsub.getSubscriptions(); 

   // Check each subscription for activity 
   for (const subscription of subscriptions) { 
     const [messages] = await pubsub 
       .topic(subscription.metadata.topic) 
       .subscription(subscription.name) 
       .seekToTime('2023-01-01T00:00:00Z') // Seek to the beginning of time 
       .get(); 

     if (messages.length === 0) { 
       console.log(`Subscription ${subscription.name} is empty (no messages). It may be a candidate for cleanup.`); 
       // You can add code here to perform cleanup actions for dead subscriptions 
     } else { 
       console.log(`Subscription ${subscription.name} has messages and is active.`); 
     } 
   } 
 } catch (error) { 
    console.error(`Error discovering dead subscriptions: ${error.message}`); 
 } 
} 

// Run the function to discover dead subscriptions 
discoverDeadSubscriptions();

another:

const { PubSub } = require('@google-cloud/pubsub'); 
const pubsub = new PubSub(); 
const projectName = 'YOUR_PROJECT_ID'; 

const checkDeadSubscriptions = async () => { 
  const subscriptions = await pubsub.getSubscriptions(); 

  for (const subscription of subscriptions) { 
    const subscriptionName = subscription.name; 
    const subscriptionData = await pubsub.subscriptionMetadata(subscriptionName); 
    const lastAcknowledged = subscriptionData.ackId; 
    const lastPublished = subscriptionData.pubsubMessage.publishTime; 
    const timeSinceLastMessage = Date.now() - lastPublished; 

    // Check if it has been more than one month since the last message was published 
    if (timeSinceLastMessage > 2592000000) { // 1 month in milliseconds 
      console.log(`Potentially dead subscription: ${subscriptionName}`); 
    } 
  } 
}; 
checkDeadSubscriptions(); 

I'd greatly appreciate your help in resolving the issues with these scripts. Thanks a bunch for your time and assistance.

Best regards,

[feywind]

I can't really help with code writing but I do think it's worth asking, why do those subscriptions go dark? Is it something you expect in your app, or do messages just quit being delivered, or what?

[anaskhandevops]

Hello, thank you for your response. I would like to delete a message backlog that has accumulated to over 200K messages. To achieve this, I need to identify and remove old, inactive subscriptions among the 130 pubsub subscriptions I have.