gke-platform-security

SKILL.md

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)