policy-library/policies/templates/gcp_gke_private_cluster_v1.yaml

# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Check to see if the GKE Cluster is a private cluster.
# Part of https://cloud.google.com/kubernetes-engine/docs/how-to/hardening-your-cluster#restrict_cluster_discovery_rbac_permissions

apiVersion: templates.gatekeeper.sh/v1alpha1
kind: ConstraintTemplate
metadata:
  name: gcp-gke-private-cluster-v1
spec:
  crd:
    spec:
      names:
        kind: GCPGKEPrivateClusterConstraintV1
      validation:
        openAPIV3Schema:
          properties: {}
  targets:
    validation.gcp.forsetisecurity.org:
      rego: |
        #
        # Copyright 2021 Google LLC
        #
        # Licensed under the Apache License, Version 2.0 (the "License");
        # you may not use this file except in compliance with the License.
        # You may obtain a copy of the License at
        #
        #     https://www.apache.org/licenses/LICENSE-2.0
        #
        # Unless required by applicable law or agreed to in writing, software
        # distributed under the License is distributed on an "AS IS" BASIS,
        # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        # See the License for the specific language governing permissions and
        # limitations under the License.
        #

        package templates.gcp.GCPGKEPrivateClusterConstraintV1

        import data.validator.gcp.lib as lib

        deny[{
        	"msg": message,
        	"details": metadata,
        }] {
        	constraint := input.constraint
        	asset := input.asset
        	asset.asset_type == "container.googleapis.com/Cluster"

        	cluster := asset.resource.data
        	private_cluster_config := lib.get_default(cluster, "privateClusterConfig", {})
        	private_cluster_config == {}

        	message := sprintf("Cluster %v is not private.", [asset.name])
        	metadata := {"resource": asset.name}
        }
        #ENDINLINE