README.md

policy-controller

The Helm chart for Policy Controller

Homepage: https://github.com/sigstore/policy-controller

Maintainers

Name	Email	Url
dlorenc
hectorj2f

Source Code

• https://github.com/sigstore/policy-controller

Values

Key	Type	Default	Description
commonAnnotations	object	{}
commonNodeSelector	object	{}
commonTolerations	list	[]
cosign.cosignPub	string	""
cosign.webhookName	string	"policy.sigstore.dev"
imagePullSecrets	list	[]
installCRDs	bool	true
leasescleanup.image.pullPolicy	string	"IfNotPresent"
leasescleanup.image.repository	string	"cgr.dev/chainguard/kubectl"
leasescleanup.image.version	string	"latest-dev"
loglevel	string	"info"
serviceMonitor.enabled	bool	false
webhook.configData	object	{}
webhook.customLabels	object	{}
webhook.env	object	{}
webhook.extraArgs	object	{}
webhook.failurePolicy	string	"Fail"
webhook.image.pullPolicy	string	"IfNotPresent"
webhook.image.repository	string	"ghcr.io/sigstore/policy-controller/policy-controller"
webhook.image.version	string	"sha256:f291fce5b9c1a69ba54990eda7e0fe4114043b1afefb0f4ee3e6f84ec9ef1605"	"v0.8.2"
webhook.name	string	"webhook"
webhook.namespaceSelector.matchExpressions[0].key	string	"policy.sigstore.dev/include"
webhook.namespaceSelector.matchExpressions[0].operator	string	"In"
webhook.namespaceSelector.matchExpressions[0].values[0]	string	"true"
webhook.podDisruptionBudget.enabled	bool	true
webhook.podDisruptionBudget.minAvailable	int	1
webhook.podSecurityContext.allowPrivilegeEscalation	bool	false
webhook.podSecurityContext.capabilities.drop[0]	string	"ALL"
webhook.podSecurityContext.enabled	bool	true
webhook.podSecurityContext.readOnlyRootFilesystem	bool	true
webhook.podSecurityContext.runAsUser	int	1000
webhook.registryCaBundle	object	{}
webhook.replicaCount	int	1
webhook.resources.limits.cpu	string	"200m"
webhook.resources.limits.memory	string	"512Mi"
webhook.resources.requests.cpu	string	"100m"
webhook.resources.requests.memory	string	"128Mi"
webhook.securityContext.enabled	bool	false
webhook.securityContext.runAsUser	int	65532
webhook.service.annotations	object	{}
webhook.service.port	int	443
webhook.service.type	string	"ClusterIP"
webhook.serviceAccount.annotations	object	{}
webhook.serviceAccount.create	bool	true
webhook.serviceAccount.name	string	""
webhook.volumeMounts	list	[]
webhook.volumes	list	[]
webhook.webhookNames.defaulting	string	"defaulting.clusterimagepolicy.sigstore.dev"
webhook.webhookNames.validating	string	"validating.clusterimagepolicy.sigstore.dev"

Deploy policy-controller Helm Chart

Install policy-controller using Helm:

helm repo add sigstore https://sigstore.github.io/helm-charts
helm repo update
kubectl create namespace cosign-system
helm install policy-controller -n cosign-system sigstore/policy-controller --devel

The policy-controller enforce images matching the defined list of ClusterImagePolicy for the labeled namespaces.

Note that, by default, the policy-controller offers a configurable behavior defining whether to allow, deny or warn whenever an image does not match a policy in a specific namespace. This behavior can be configured using the config-policy-controller ConfigMap created under the release namespace, and by adding an entry with the property no-match-policy and its value warn|allow|deny. By default, any image that does not match a policy is rejected whenever no-match-policy is not configured in the ConfigMap.

As supported in previous versions, you could create your own key pair:

export COSIGN_PASSWORD=<my_cosign_password>
cosign generate-key-pair

This command generates two key files cosign.key and cosign.pub. Next, create a secret to validate the signatures:

kubectl create secret generic mysecret -n \
cosign-system --from-file=cosign.pub=./cosign.pub

IMPORTANT: The cosign.secretKeyRef flag is not supported anymore. Finally, you could reuse your secret mysecret by creating a ClusterImagePolicy that sets it as listed authorities, as shown below.

apiVersion: policy.sigstore.dev/v1alpha1
kind: ClusterImagePolicy
metadata:
  name: cip-key-secret
spec:
  images:
  - glob: "**your-desired-value**"
  authorities:
  - key:
      secretRef:
        name: mysecret

Configuring Custom Certificate Authorities (CA)

The policy-controller can be configured to use custom CAs to communicate to container registries, for example, when you have a private registry with a self-signed TLS certificate.

To configure policy-controller to use custom CAs, follow these steps:

1. Make sure the policy-controller namespace exists:

   kubectl create namespace cosign-system

2. Create a bundle file with all the root and intermediate certificates and name it ca-bundle.crt.

3. Create a ConfigMap from the bundle:

   kubectl -n cosign-system create cm ca-bundle-config \
     --from-file=ca-bundle.crt="ca-bundle.crt"

4. Install the policy-controller:

   helm install -n cosign-system \
     --set webhook.registryCaBundle.name=ca-bundle-config \
     --set webhook.registryCaBundle.key=ca-bundle.crt \
     policy-controller sigstore/policy-controller

Enabling Admission control

To enable the policy admission webhook to check for signed images, you will need to add the following label in each namespace that you would want the webhook triggered:

Label: policy.sigstore.dev/include: "true"

apiVersion: v1
kind: Namespace
metadata:
  labels:
    policy.sigstore.dev/include: "true"
    kubernetes.io/metadata.name: my-namespace
  name: my-namespace
spec:
  finalizers:
  - kubernetes

Testing the webhook

1. Using Unsigned Images: Creating a deployment referencing images that are not signed will yield the following error and no resources will be created:

   kubectl apply -f my-deployment.yaml
   Error from server (BadRequest): error when creating "my-deployment.yaml": admission webhook "policy.sigstore.dev" denied the request: validation failed: invalid image signature: spec.template.spec.containers[0].image

2. Using Signed Images: Assuming a signed nginx image with a tag signed exists on a registry, the resource will be successfully created.

   kubectl run pod1-signed  --image=< REGISTRY_USER >/nginx:signed -n testns
   pod/pod1-signed created

More info

You can find more information about the policy-controller in here.