What should you do to ensure a legacy application retrieves its configuration before serving traffic in GKE?

Creating a PersistentVolumeClaim (PVC) to access configuration files is a robust approach for ensuring that a legacy application retrieves its configuration before serving traffic in Google Kubernetes Engine (GKE). The use of PVC allows you to define the storage requirements for your application in a declarative way.

With a PVC, you can effectively use a PersistentVolume (PV) that can hold the configuration files your application needs. This storage system ensures that the configuration data is accessible to your application pods at startup. The configurations can be stored on various backends supported by Kubernetes, such as Google Cloud Storage, NFS, or other supported volumes. When the pod starts, it can mount the volume defined by the PVC and read the configuration files, ensuring that the application has access to the necessary settings prior to being available for traffic.

This method is advantageous because it separates storage management from application management, allows for easier updates to configuration data without needing to update the container image, and can facilitate sharing configuration across multiple pods if needed.

Using gsutil to copy files at startup wouldn't ensure that the configuration is read before the application starts serving traffic, as it could introduce delays or failures if the copy process does not complete in time. The COPY statement in the Dockerfile, although it can