GKE Cost Optimization

This reference covers strategies and workflows for reducing Google Kubernetes Engine (GKE) costs while maintaining a secure and reliable posture.

MCP Tools: get_k8s_resource, describe_k8s_resource, apply_k8s_manifest, patch_k8s_resource, get_cluster

Golden Path Cost Features

The golden path already includes cost-optimizing settings:

Workflows & Optimization Strategies

1. Prerequisite: Cost Allocation & Monitoring

To enable GKE cost allocation (--enable-cost-allocation) for billing tracking across namespaces and labels, inspect live cluster utilization (kubectl top), or run historical cost breakdown queries in BigQuery (bq), use the gke-cost-analysis skill. Once tracking is active and waste is diagnosed, apply the optimization workflows below.

2. Configure Resource Quotas

Resource quotas restrict total resource consumption across tenants in multi-tenant clusters, preventing runaway costs.

kubectl apply -f - <<EOF
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-quota
  namespace: {namespace}
spec:
  hard:
    requests.cpu: "4"
    requests.memory: 16Gi
    limits.cpu: "8"
    limits.memory: 32Gi
EOF

3. Pod Rightsizing (VPA & MPA)

Adjust pod resource requests to match actual utilization. Over-provisioned requests are one of the largest sources of waste.

• Use VPA in Recommendation Mode:

# 1. Deploy VPA in recommendation mode
kubectl apply -f - <<EOF
apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: {deployment_name}-vpa
spec:
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: {deployment_name}
  updatePolicy:
    updateMode: "Off"
EOF

# 2. Wait 24+ hours for data collection

# 3. Read recommendations
kubectl get vpa {deployment_name}-vpa -o jsonpath='{.status.recommendation}'

• Optimization Rules:

• Use MPA: Reconcile HPA and VPA recommendations when scaling both horizontally and vertically to avoid conflicting scale events.
• Review Cost Recommendations: Check Google Cloud Console (Cost Management > GKE Cost Optimization) for built-in rightsizing suggestions.

4. Spot VMs via ComputeClasses & NodeSelector

Use Spot VMs for fault-tolerant workloads to achieve 60-90% cost reduction.

4.1 ComputeClass Configuration

apiVersion: cloud.google.com/v1
kind: ComputeClass
metadata:
  name: spot-with-fallback
spec:
  activeMigration:
    optimizeRulePriority: true
  priorities:
  - machineFamily: n4
    spot: true
  - machineFamily: n4
    spot: false

4.2 Direct Workload Spot Selection (nodeSelector)

For stateless or batch workloads in GKE Autopilot, target Spot capacity directly using nodeSelector:

[!WARNING] Preemption Warning: Spot VMs are interruptible and can be preempted at any time with a 30-second notice. Workloads must be fault-tolerant and run with at least 2 replicas for high availability. Always explicitly warn users about this preemption risk when recommending Spot VMs.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: stateless-spot-app
spec:
  replicas: 2
  template:
    spec:
      nodeSelector:
        cloud.google.com/gke-provisioning: Spot
      terminationGracePeriodSeconds: 25  # Must be < 30s for Spot preemption handling
      containers:
      - name: app
        image: {image_name}
        lifecycle:
          preStop:
            exec:
              command: ["/bin/sh", "-c", "sleep 5"]

Spot-Suitable Workloads:

5. Machine Type Selection

When choosing node shapes or configuring ComputeClasses:

6. Committed Use Discounts (CUDs)

For steady-state workloads with predictable baseline usage, purchase 1-year or 3-year CUDs:

• 1-year: ~20-30% discount
• 3-year: ~50-55% discount
• Applied automatically to matching usage across the region.
• Purchase via Google Cloud Console > Billing > Committed use discounts.

7. Cluster Management & Multi-Tenancy

• Stop/start dev clusters: Idle dev clusters cost money even with no workloads due to control plane fees.
• Right-size node pools (Standard): Use Cluster Autoscaler with appropriate min/max limits.
• Multi-tenant consolidation: Share a single cluster across multiple engineering teams instead of maintaining per-team clusters, using Namespaces and ResourceQuotas to isolate workloads.

Cost & Utilization Monitoring

To inspect live node/pod utilization (kubectl top nodes/pods), view cluster cost budgets (gcloud billing budgets list), or query detailed billing reports in BigQuery (bq query), refer to the gke-cost-analysis skill.

Dev/Test Cost Savings

For non-production environments, the following golden path deviations provide cost efficiency without impacting production safety:

| Setting | Production (Golden | Dev/Test |

Best Practices Summary

1. Enable Cost Allocation: Always enable GKE cost allocation (--enable-cost-allocation) to gain billing transparency across namespaces and labels.
2. Enforce Resource Quotas: Restrict namespace CPU/memory limits in multi-tenant environments to prevent runaway costs or noisy neighbors.
3. Rightsize Continuously: Run VPA in recommendation mode (updateMode: Off) and adjust requests to match P95 * 1.2.
4. Leverage Spot VMs: Use Spot VMs with nodeSelector or ComputeClass for stateless, fault-tolerant workloads to save 60-90%.
5. Optimize Autoscaling Profile: Use OPTIMIZE_UTILIZATION for aggressive node scale-down on idle compute.
6. Consolidate & Clean Up: Stop idle development clusters and consolidate multi-team workloads into shared multi-tenant clusters.