gke-platform-security

GKE Platform Security

This reference covers platform-level security hardening and cluster

configuration for Google Kubernetes Engine (GKE). For workload-level security

controls (such as Workload Identity Service Account bindings,

SecretProviderClass volume mounts, Network Policies, and Pod Security

Standards), refer to the gke-workload-security skill.

> MCP Tools: gke:get_cluster, k8s:check_k8s_auth,

> k8s:get_k8s_resource, k8s:apply_k8s_manifest, gke:update_cluster

Golden Path Security Defaults

Setting | Golden Path Value | Day-0/1 | Notes

-------------------------------------------------------------- | --------------------------------------- | ------- | -----

workloadIdentityConfig.workloadPool | <PROJECT>.svc.id.goog | Day-0 | Workload Identity Federation for cluster pods

secretManagerConfig.enabled | true | Day-1 | Google Secret Manager cluster add-on integration

secretManagerConfig.rotationConfig | enabled: true, rotationInterval: 120s | Day-1 | Automatic secret rotation at the cluster level

rbacBindingConfig.enableInsecureBindingSystemAuthenticated | false | Day-0 | Blocks legacy system:authenticated bindings

rbacBindingConfig.enableInsecureBindingSystemUnauthenticated | false | Day-0 | Blocks legacy system:unauthenticated bindings

nodeConfig.shieldedInstanceConfig.enableSecureBoot | true | Day-0 | Verifiable boot integrity

nodeConfig.shieldedInstanceConfig.enableIntegrityMonitoring | true | Day-0 | Runtime integrity checks

nodeConfig.workloadMetadataConfig.mode | GKE_METADATA | Day-0 | Blocks legacy metadata API, enforces Workload Identity

Private cluster + Dataplane V2 settings | See the gke-networking skill | Day-0 | Private nodes, private endpoint enforcement, ADVANCED_DATAPATH

Secret Manager Add-on Enablement

The golden path enables Secret Manager at the cluster level with automatic

secret rotation.

# Verify Secret Manager is enabled on cluster
gcloud container clusters describe <CLUSTER_NAME> --region <REGION> \
  --format="value(secretManagerConfig.enabled)" \
  --quiet

# Enable if not already (Day-1 change)
gcloud container clusters update <CLUSTER_NAME> --region <REGION> \
  --enable-secret-manager \
  --secret-manager-rotation-interval=120s \
  --quiet

> Note: For configuring SecretProviderClass manifests and mounting secrets

> as volumes inside application deployments, see the gke-workload-security

> skill.

RBAC Hardening

The golden path disables insecure legacy RBAC bindings that grant broad access

to system:authenticated and system:unauthenticated groups.

# Verify insecure bindings are disabled
gcloud container clusters describe <CLUSTER_NAME> --region <REGION> \
  --format="yaml(rbacBindingConfig)" \
  --quiet

Best practices for RBAC:

• Use namespace-scoped Roles over cluster-wide ClusterRoles.
• Bind to specific Groups or ServiceAccounts, never to system:authenticated

or system:unauthenticated.

• Audit permissions via MCP: `k8s:check_k8s_auth(parent="...", verb="list",

resourceType="pods", namespace="...") (or kubectl auth can-i --list

--as=<user>`).

• Review bindings via MCP: `k8s:get_k8s_resource(parent="...",

resourceType="clusterrolebinding") (or kubectl get

clusterrolebindings,rolebindings --all-namespaces`).

> See the gke-multitenancy skill for enterprise RBAC planning and

> https://docs.cloud.google.com/kubernetes-engine/docs/best-practices/rbac.md.txt

Binary Authorization

Not enabled in golden path by default but recommended for enforcing production

image provenance across the cluster:

# Enable Binary Authorization
gcloud container clusters update <CLUSTER_NAME> --region <REGION> \
  --binauthz-evaluation-mode=PROJECT_SINGLETON_POLICY_ENFORCE \
  --quiet

Shielded Nodes & GKE Sandbox Enablement

Enabling verifiable node boot integrity and kernel isolation features at the

cluster level:

# Enable Shielded Nodes on an existing cluster
gcloud container clusters update <CLUSTER_NAME> --region <REGION> \
  --enable-shielded-nodes \
  --quiet

# Enable GKE Sandbox (gVisor) runtime on an existing cluster
gcloud container clusters update <CLUSTER_NAME> --region <REGION> \
  --enable-gke-sandbox \
  --quiet

> Note: To run workloads inside the gVisor sandbox, specify

> runtimeClassName: gvisor in your Pod specs as detailed in the

> gke-workload-security skill.

Common IAM Roles

The five most common predefined IAM roles for GKE platform and cluster access:

| Role | Purpose | When to Use |

| ------------------------------- | ------------------- | -------------------- |

| roles/container.admin | Full control over | Platform team admins |

: : clusters and : managing cluster :

: : Kubernetes : lifecycle :

: : resources : :

| roles/container.clusterAdmin | Manage clusters but | Cluster operators |

: : not project-level : who create/delete :

: : IAM : clusters :

| roles/container.developer | Deploy workloads | Application |

: : (pods, services, : developers deploying :

: : deployments) : to existing clusters :

| roles/container.viewer | Read-only access to | Monitoring, |

: : clusters and : auditing, or :

: : Kubernetes : read-only dashboards :

: : resources : :

| roles/container.clusterViewer | List and get | CI/CD pipelines that |

: : cluster details : need cluster :

: : only : metadata :

> Principle of least privilege: Start with roles/container.viewer or

> roles/container.developer and escalate only as needed. Avoid granting

> roles/container.admin broadly across teams.

Service Accounts & Agents

• GKE Service Agent

(service-<PROJECT_NUMBER>@container-engine-robot.iam.gserviceaccount.com):

Automatically created. Manages nodes, networking, and cluster operations on

your behalf. Do not remove or modify its permissions.

• Node Service Account: By default, nodes use the Compute Engine default

service account. For production platforms, create a dedicated Google Service

Account with minimal required permissions (roles/monitoring.metricWriter,

roles/logging.logWriter) and assign it at node pool creation time.

• Workload Identity: For binding Google Service Accounts to Kubernetes

Service Accounts (roles/iam.workloadIdentityUser), refer to the

gke-workload-security skill.

Cross-Service Authentication Patterns

Common project-level IAM policy binding patterns for granting backend Google

Service Accounts (GSAs) access to external Google Cloud services before linking

via Workload Identity:

# Grant a GSA access to Cloud Storage objects
gcloud projects add-iam-policy-binding <PROJECT_ID> \
  --member "serviceAccount:<GSA_NAME>@<PROJECT_ID>.iam.gserviceaccount.com" \
  --role "roles/storage.objectViewer" \
  --quiet

# Grant a GSA access to Cloud SQL databases
gcloud projects add-iam-policy-binding <PROJECT_ID> \
  --member "serviceAccount:<GSA_NAME>@<PROJECT_ID>.iam.gserviceaccount.com" \
  --role "roles/cloudsql.client" \
  --quiet

# Grant a GSA access to Pub/Sub subscriptions
gcloud projects add-iam-policy-binding <PROJECT_ID> \
  --member "serviceAccount:<GSA_NAME>@<PROJECT_ID>.iam.gserviceaccount.com" \
  --role "roles/pubsub.subscriber" \
  --quiet

## Resources

- [GKE Cluster Hardening Guide](https://cloud.google.com/kubernetes-engine/docs/how-to/hardening-your-cluster)
- [GKE RBAC Best Practices](https://cloud.google.com/kubernetes-engine/docs/best-practices/rbac)
- [Secret Manager Add-on for GKE](https://cloud.google.com/secret-manager/docs/secret-manager-managed-csi-component)
- [Binary Authorization on GKE](https://cloud.google.com/binary-authorization/docs/setting-up)
- [Shielded GKE Nodes](https://cloud.google.com/kubernetes-engine/docs/how-to/shielded-gke-nodes)
- [GKE Sandbox (gVisor)](https://cloud.google.com/kubernetes-engine/docs/how-to/sandbox-pods)