GKE集群迁移技术问询：默认VPC转共享/自定义VPC、公集群转私集群

Hey there, let's break down your GKE cluster migration questions one by one, based on GCP's current capabilities:

1. Can a Default VPC GKE cluster be migrated to Shared VPC or Custom VPC? #

• First off, there's no direct way to convert an existing Default VPC cluster to either Shared VPC or Custom VPC—network configurations like VPC type are baked into the cluster at creation time and can't be modified post-deployment.
• To move to a Custom VPC, your only viable path is:
  1. Provision a new GKE cluster that uses your target Custom VPC and its subnets (make sure to align subnet settings like IP ranges, firewall rules, and routing with your workload requirements).
  2. Migrate all your Kubernetes resources (deployments, services, configmaps, secrets, statefulsets, etc.) from the old Default VPC cluster to the new Custom VPC one.

2. How to migrate a Custom VPC GKE cluster to Shared VPC? #

Just like the Default VPC scenario, you can't directly reconfigure an existing Custom VPC cluster to use Shared VPC. The standard approach is:

1. Prepare the Shared VPC environment: Ensure you have the necessary permissions (like compute.networkAdmin on the Shared VPC host project, and container.admin on the service project where you'll deploy the new cluster). You'll also need to create or designate subnets in the Shared VPC for the GKE cluster, and grant the GKE service account access to those subnets.
2. Create a new GKE cluster in Shared VPC: When setting up the cluster, select the Shared VPC host project and target subnet(s) during the network configuration step.
3. Migrate Kubernetes resources: Use tools like kubectl (exporting resources with kubectl get <resource-type> -o yaml and applying them to the new cluster) or a backup/restore tool like Velero for stateful workloads. For managed resources like GKE Ingress, you'll need to recreate them in the new cluster to ensure they bind correctly to the Shared VPC's networking resources.

3. Converting a public GKE cluster to private mode—does this require a new cluster? #

You're spot on: there's no in-place conversion from a public GKE cluster to private mode. Private cluster settings (like restricting control plane access to private IPs only, or limiting node outbound traffic through Cloud NAT) are set at cluster creation and can't be toggled later.

To switch to private mode:

1. Deploy a new GKE cluster configured as private (during setup, enable "Private cluster" options, set up private control plane endpoints, and configure access via VPN, Cloud Interconnect, or Private Service Connect if needed).
2. Migrate your workloads and resources to the new private cluster, using the same methods mentioned in the previous questions (kubectl exports, Velero backups, etc.).
3. Once validation is complete, decommission the old public cluster.

内容的提问来源于stack exchange，提问作者Zama Ques