OPA Gatekeeper

OPA Gatekeeper
Terraform module for Kubernetes platforms

OPA Gatekeeper is a Kubernetes admission controller to meet governance and legal requirements and ensure adherence to best practices and institutional conventions for manifests applied to a cluster.

This Terraform module helps platform engineering teams provision OPA Gatekeeper on Kubernetes. It fully integrates the upstream Kubernetes resources into the Terraform plan/apply lifecycle and allows configuring OPA Gatekeeper using native Terraform syntax.

The OPA Gatekeeper module is continuously updated and tested when new upstream versions are released.

Build status for opa-gatekeeper-v3.16.3-kbst.0


  • Use kbst add service opa-gatekeeper to add OPA Gatekeeper to your platform
  • The kbst CLI scaffolds the Terraform module boilerplate for you
  • Kubestack platform service modules bundle upstream manifests and are fully customizable

Use the module

The kbst CLI helps you scaffold the Terraform code to provision OPA Gatekeeper on your platform. It takes care of calling the module once per cluster, and sets the correct source and latest version for the module. And it also makes sure the module's configuration and configuration_base_key match your platform.

# add OPA Gatekeeper service to all platform clusters
kbst add service opa-gatekeeper
# or optionally only add OPA Gatekeeper to a single cluster
# 1. list existing platform modules
kbst list
# 2. add OPA Gatekeeper to a single cluster
kbst add service opa-gatekeeper --cluster-name aks_gc0_westeurope

Scaffolding the boilerplate is convenient, but platform service modules are fully documented, standard Terraform modules. They can also be used standalone without the Kubestack framework.

Customize resources

All Kubestack platform service modules support the same module attributes and configuration as all Kubestack modules. The module configuration is a Kustomization set in the per environment configuration map following Kubestack's inheritance model.

The example below shows some options to customize the resources provisioned by the OPA Gatekeeper module.

module "example_opa_gatekeeper" {
providers = {
kustomization = kustomization.example
source = "kbst.xyz/catalog/opa-gatekeeper/kustomization"
version = "3.16.3-kbst.0"
configuration = {
apps = {
+ # change the namespace of all resources
+ namespace = var.example_opa_gatekeeper_namespace
+ # or add an annotation
+ common_annotations = {
+ "terraform-workspace" = terraform.workspace
+ }
+ # use images to pull from an internal proxy
+ # and avoid being rate limited
+ images = [{
+ # refers to the 'pod.spec.container.name' to modify the 'image' attribute of
+ name = "container-name"
+ # customize the 'registry/name' part of the image
+ new_name = "reg.example.com/nginx"
+ }]
ops = {
+ # scale down replicas in ops
+ replicas = [{
+ # refers to the 'metadata.name' of the resource to scale
+ name = "example"
+ # sets the desired number of replicas
+ count = 1
+ }]

In addition to the example attributes shown above, modules also support secret_generator, config_map_generator, patches and many other Kustomization attributes.

Full documentation how to customize a module's Kubernetes resources is available in the platform service module configuration section of the framework documentation.