---
name: gke-cost
description: >-
  Optimizes GKE costs, rightsizes workloads, and configures Spot VMs and CUDs.
  Use when optimizing GKE costs, rightsizing GKE workloads, or configuring GKE
  Spot VMs. Don't use for general compute class provisioning or GPU Selection
  (use gke-compute-classes instead).
metadata:
  category: CloudObservabilityAndMonitoring
---

# GKE Cost Optimization

This reference covers strategies for reducing GKE costs while maintaining the
golden path security and reliability 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:

| Setting                  | Value                  | Impact                  |
| ------------------------ | ---------------------- | ----------------------- |
| `autoscalingProfile`     | `OPTIMIZE_UTILIZATION` | Aggressive node         |
:                          :                        : scale-down reduces idle :
:                          :                        : compute                 :
| `verticalPodAutoscaling` | `enabled`              | VPA recommendations     |
:                          :                        : prevent                 :
:                          :                        : over-provisioning       :
| Autopilot pricing        | Pay per pod request    | No charge for unused    |
:                          :                        : node capacity           :
| Node Auto Provisioning   | enabled                | Right-sized node pools  |
:                          :                        : created automatically   :

## Cost Optimization Strategies

### 1. Spot VMs via ComputeClasses

Use Spot VMs for fault-tolerant workloads (60-90% cost reduction).

```yaml
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
```

**Spot-suitable workloads:**

Workload                          | Spot-Suitable?
--------------------------------- | ---------------
Batch / data processing           | Yes
Dev / test environments           | Yes
Stateless web/API (replicas >= 2) | Yes (with PDBs)
Jobs with checkpointing           | Yes
Stateful workloads (databases)    | No
Single-replica critical services  | No

**Handling eviction:**

```yaml
spec:
  template:
    spec:
      terminationGracePeriodSeconds: 25  # Must be < 30s for Spot
      containers:
      - name: app
        lifecycle:
          preStop:
            exec:
              command: ["/bin/sh", "-c", "sleep 5"]
```

### 1.1 Direct Workload Spot Selection (NodeSelector)

For stateless or batch workloads in GKE Autopilot, you do not need to create a
custom ComputeClass to use Spot VMs. You can target the built-in Spot capacity
directly by adding a `nodeSelector` to your Pod or Deployment spec.

> [!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.

```yaml
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 to allow graceful shutdown before preemption
      containers:
      - name: app
        image: <IMAGE>
```

### 2. Pod Rightsizing

Use VPA recommendations to reduce over-provisioned requests.

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

# 2. Wait 24+ hours for data collection

# 3. Read recommendations
kubectl get vpa <DEPLOYMENT>-vpa -o jsonpath='{.status.recommendation}'
```

**Optimization rules:**

Condition                     | Action                             | Savings
----------------------------- | ---------------------------------- | -------
CPU request >5x P95 actual    | Reduce to `P95 * 1.2`              | High
Memory request >3x P95 actual | Reduce to `P95 * 1.2`              | High
CPU request >2x P95 actual    | Reduce to `P95 * 1.2`              | Medium
No resource requests set      | Add requests (enables bin-packing) | Medium

### 3. Machine Type Selection

| Family        | Use Case                                     | Relative Cost |
| ------------- | -------------------------------------------- | ------------- |
| e2            | General purpose, burstable                   | Lowest        |
| t2a / t2d     | Scale-out (Arm/AMD), price-performance       | Low           |
:               : optimized                                    :               :
| n4a           | Axion Arm-based, general-purpose             | Low           |
:               : price-performance                            :               :
| n4 / n4d      | General purpose (Intel/AMD), flexible shapes | Low-Medium    |
| c4a           | Compute-optimized (Arm), high efficiency     | Medium-High   |
| c3 / c4       | Compute-optimized (Intel)                    | Medium-High   |
| c3d / c4d     | Compute-optimized (AMD), high-performance    | Medium-High   |
:               : throughput                                   :               :
| ek-standard   | Autopilot enhanced (golden path)             | Medium        |
| m3 / x4       | Memory-optimized, SAP HANA, large databases  | High          |
| g2 (L4 GPU)   | AI inference                                 | High          |
| a3 (H100 GPU) | AI training                                  | Highest       |
| a4 / a4x      | Ultra-scale AI (Blackwell GPUs)              | Highest       |

> In Autopilot, machine type is managed. Use ComputeClasses to influence
> selection.

### 4. Committed Use Discounts (CUDs)

For steady-state workloads, purchase 1-year or 3-year CUDs:

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

### 5. Cluster Management

-   **Stop/start dev clusters**: Idle dev clusters cost money even with no
    workloads (control plane fee).
-   **Right-size node pools** (Standard): Use Cluster Autoscaler with
    appropriate min/max.
-   **Multi-tenant clusters**: Share a single cluster across teams instead of
    per-team clusters (see the `gke-multitenancy` skill).

## Cost Monitoring

```bash
# View cluster cost breakdown (requires Cost Management API)
gcloud billing budgets list --billing-account=<BILLING_ACCOUNT> --quiet

# View node utilization
kubectl top nodes

# View pod resource usage vs requests
kubectl top pods --all-namespaces --containers
```

## Dev/Test Cost Savings

For non-production environments, these golden path deviations are acceptable:

| Setting                 | Production (Golden | Dev/Test                      |
:                         : Path)              :                               :
| ----------------------- | ------------------ | ----------------------------- |
| Cluster mode            | Autopilot          | Autopilot (cheaper with fewer |
:                         :                    : pods)                         :
| Release channel         | Regular            | Rapid (get fixes faster)      |
| Private nodes           | Required           | Optional (simpler access)     |
| Monitoring components   | Full suite         | SYSTEM_COMPONENTS only        |
| Secret Manager rotation | 120s               | Disabled                      |
| Maintenance windows     | Configured         | Not needed                    |