Introduction

When working with Google Cloud AlloyDB for PostgreSQL, you may notice that the instance state remains READY even while undergoing updates. This can lead to confusion, especially when programmatically monitoring instance status. After some investigation, I discovered that the correct way to determine if an update is in progress is by checking the Reconciling property.

The Problem: Always ‘READY’

When querying the instance status using the Google Cloud AlloyDB V1 API or SDK, the state property often returns READY, even if maintenance or updates are occurring. For example:

{
  "name": "projects/my-project/locations/us-central1/clusters/my-cluster/instances/my-instance",
  "state": "READY",
  "databaseVersion": "POSTGRES_14",
  "reconciling": true
}

At first glance, this suggests that the instance is fully operational. However, in reality, an update might still be in progress.

The Solution: Checking the ‘Reconciling’ Property

To accurately determine if an instance is undergoing updates, you should check the reconciling field. When reconciling: true, it means that AlloyDB is in the process of updating, even if the state remains READY.

Example: Correct Monitoring Logic

If you’re writing a script to check whether an AlloyDB instance is updating, use the following logic:

import google.cloud.alloydb_v1 as alloydb

def check_instance_status(project_id, location, cluster_id, instance_id):
    client = alloydb.AlloyDBAdminClient()
    instance_name = f"projects/{project_id}/locations/{location}/clusters/{cluster_id}/instances/{instance_id}"
    instance = client.get_instance(name=instance_name)
    
    if instance.reconciling:
        print(f"Instance {instance_id} is updating.")
    else:
        print(f"Instance {instance_id} is stable.")

This approach ensures that you don’t mistakenly assume an instance is fully available while it’s still undergoing updates.

Conclusion

If you’re using AlloyDB for PostgreSQL and monitoring instance status, don’t rely solely on the state property. Instead, check the reconciling field to determine whether an update is in progress. This will help you avoid unexpected issues when managing database instances in production.

For more details, refer to the Google Cloud AlloyDB documentation.