niccoloraspa/talk-kcd-italy-2021-opa-gatekeeper

Repository for the talk "Tu non puoi passare! Policy compliance con OPA Gatekeeper" presented at KCD Italy 2021

KCD Italy 2021 Demo 🍕 ☸️🇮🇹

Repository for the talk "Tu non puoi passare! Policy compliance con OPA Gatekeeper" presented at KCD Italy 2021 🇮🇹.

Slides are available under ./slides/

☸️ Setup Minikube Cluster

1. Create minikube cluster

make minikube

🔨 Deploy OPA Gatekeeper and Gatekeeper Policy Manager

1. Deploy OPA Gatekeeper 3.5:

kubectl apply -f https://raw.githubusercontent.com/open-policy-agent/gatekeeper/release-3.5/deploy/gatekeeper.yaml
# Local version available at ./manifests/gatekeeper.yaml

2. Deploy Gatekeeper Policy Manager v0.5.0:

kubectl apply -k https://github.com/sighupio/gatekeeper-policy-manager/
# Local version available at ./manifests/gatekeeper-policy-manager.yaml

3. Port forward Gatekeeper Policy Manager UI on localhost:8080:

kubectl port-forward svc/gatekeeper-policy-manager -n gatekeeper-system 8080:80 2>&1 >/dev/null &

🚔 Deploy OPA Policies

⛔ Policy #1 - Mandatory label in namespaces

1. Create our first ContraintTemplate:

kubectl apply -f manifests/rules/0-ns-require-labels/template.yaml

A ConstraintTemplate describes both the Rego that enforces the constraint and the schema of the constraint.

2. Check the creation of the related resources:

kubectl get constrainttemplates.templates.gatekeeper.sh

Expected Output:

NAME                     AGE
namespacerequirelabels   6m48s

3. Check the new CRD that gets created:

kubectl get crd | grep constraints

Expected Output:

namespacerequirelabels.constraints.gatekeeper.sh     2021-11-15T13:52:53Z

4. Instantiate the template with a Constraint:

kubectl apply -f manifests/rules/0-ns-require-labels/require-kcd-italy-label/constraint.yaml

Constraints are used to actually enforce a ConstraintTemplate

5. Inspect new resources:

kubectl get constraints

Expected output:

NAME                           AGE
ns-must-have-kcd-italy-label   9s

6. Test creation of a namespace bad without the kcd-italy label:

kubectl create ns bad
# kubectl apply -f manifests/rules/0-ns-require-labels/require-kcd-italy-label/example_disallowed.yaml                                  

Expected output:

Error from server ([ns-must-have-kcd-italy-label] you must provide labels: {"kcd-italy"}): admission webhook "validation.gatekeeper.sh" denied the request: [ns-must-have-kcd-italy-label] you must provide labels: {"kcd-italy"}

7. Test creation of a namespace good with the kcd-italy label:

kubectl apply -f manifests/rules/0-ns-require-labels/require-kcd-italy-label/example_allowed.yaml

Expected output:

namespace/good created

⛔ Policy #2 - Pod from trusted registries

1. Create the ContraintTemplate and the Constraint:

kubectl apply -f manifests/rules/1-pod-from-trusted-registry/template.yaml
kubectl apply -f manifests/rules/1-pod-from-trusted-registry/trust-sighup-registry/constraint.yaml

2. Check the creation of the related resources:

kubectl get constrainttemplates.templates.gatekeeper.sh,constraints

Expected Output:

NAME                                                              AGE
constrainttemplate.templates.gatekeeper.sh/trustedimageregistry   18s
# ... hiding other constrainttemplates for brevity

NAME                                                                           AGE
trustedimageregistry.constraints.gatekeeper.sh/all-pods-from-sighup-registry   9s

# ... hiding other constraints for brevity

3. Test that the Constraint allows a registry.sighup.io/workshop/nginx image:

kubectl apply -f manifests/rules/1-pod-from-trusted-registry/trust-sighup-registry/example_allowed.yaml

Expected Output:

pod/good-pod created

4. Test that the Constraint does not allow a nginx image:

kubectl apply -f manifests/rules/1-pod-from-trusted-registry/trust-sighup-registry/example_disallowed.yaml

Expected Output:

Error from server ([all-pods-from-sighup-registry] image 'nginx' comes from untrusted registry): error when creating "manifests/rules/1-pod-from-trusted-registry/trust-sighup-registry/example_disallowed.yaml": admission webhook "validation.gatekeeper.sh" denied the request: [all-pods-from-sighup-registry] image 'nginx' comes from untrusted registry

5. Try to create a deployment with an untrusted registry. What happens?

kubectl create deployment nginx-deploy --image nginx --replicas 10

Expected Output:

deployment.apps/nginx-deploy created

Are the pods running?

kubectl get deployments.apps nginx-deploy  

Expected Output:

NAME           READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deploy   0/10    0            0           6s

Try to inspect the related ReplicaSet:

kubectl describe rs $(kubectl get rs -o jsonpath='{.items[*].metadata.name}' | grep nginx-deploy)

⛔ Policy #3 - Unique ingress names

1. Create the ContraintTemplate and the Constraint:

kubectl apply -f manifests/rules/2-unique-ingress-host/template.yaml
kubectl apply -f manifests/rules/2-unique-ingress-host/unique-ingress/constraint.yaml

2. Check the creation of the related resources:

kubectl get constrainttemplates.templates.gatekeeper.sh,constraints

Expected Output:

NAME                                                              AGE
constrainttemplate.templates.gatekeeper.sh/k8suniqueingresshost   6m3s
# ... hiding other constrainttemplates for brevity

NAME                                                                 AGE
k8suniqueingresshost.constraints.gatekeeper.sh/unique-ingress-host   5m13s

# ... hiding other constraints for brevity

3. Test the Constraint:

kubectl apply -f manifests/rules/2-unique-ingress-host/unique-ingress/example_disallowed.yaml

Expected Output:

ingress.networking.k8s.io/ingress-host-1 created
ingress.networking.k8s.io/ingress-host-2 created

The Constraint is correct, but it's not working as we have not replicated any data to Gatekeeper.

4. Deploy necessary config:

kubectl apply -f manifests/rules/2-unique-ingress-host/config.yaml

3. Test the Constraint again:

kubectl delete -f manifests/rules/2-unique-ingress-host/unique-ingress/example_disallowed.yaml
kubectl apply -f manifests/rules/2-unique-ingress-host/unique-ingress/example_disallowed.yaml 

Expected Output:

ingress.networking.k8s.io/ingress-host-1 created

Error from server ([unique-ingress-host] Ingress host conflicts with an existing Ingress <example-host.example.com>
[unique-ingress-host] Ingress host conflicts with an existing Ingress <example-host.example.com>): error when creating "manifests/rules/2-unique-ingress-host/unique-ingress/example_disallowed.yaml": admission webhook "validation.gatekeeper.sh" denied the request: [unique-ingress-host] Ingress host conflicts with an existing Ingress <example-host.example.com>
[unique-ingress-host] Ingress host conflicts with an existing Ingress <example-host.example.com>

🧹 Cleanup

1. Delete minikube cluster:

make delete

📖 Additional Resources

• OPA Gatekeeper documentation
• OPA Gatekeeper Library
• OPA documentation