How to upgrade a GKE cluster created by pltf.

Overview

pltf configures the GKE release channel via gke_channel (RAPID, REGULAR, STABLE). Upgrades happen according to Google’s channel policy. You can also trigger manual upgrades with gcloud.

Option 1: Change release channel (recommended)

Update your spec:

modules:
  - id: gke
    type: gcp_gke
    inputs:
      gke_channel: "REGULAR"

pltf terraform plan -f env.yaml -e prod
pltf terraform apply -f env.yaml -e prod

Option 2: Manual upgrade with gcloud

1. Inspect available versions:

   gcloud container get-server-config --region <region>
   

2. Upgrade control plane:

   gcloud container clusters upgrade <cluster> \
     --region <region> \
     --project <project-id>
   

3. Upgrade node pools:

   gcloud container node-pools upgrade <node-pool> \
     --cluster <cluster> \
     --region <region> \
     --project <project-id>
   

Notes

• Upgrade one minor version at a time.
• Check add-on compatibility (CNI, ingress, metrics).
• For private clusters, ensure your admin network can reach the control plane before upgrading.

References

• GKE upgrades: https://cloud.google.com/kubernetes-engine/docs/how-to/upgrading-a-cluster
• Release channels: https://cloud.google.com/kubernetes-engine/docs/concepts/release-channels