Open Policy Agent (OPA)

#!/bin/bash

kubectl create namespace opa
# create Roles as they may need a second to propagate
kubectl --namespace=opa apply -f - <<EOF
# Grant OPA/kube-mgmt read-only access to resources. This lets kube-mgmt
# replicate resources into OPA so they can be used in policies.
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: opa-viewer
roleRef:
  kind: ClusterRole
  name: view
  apiGroup: rbac.authorization.k8s.io
subjects:
- kind: Group
  name: system:serviceaccounts:opa
  apiGroup: rbac.authorization.k8s.io
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gloo-view
rules:
- apiGroups:
  - gateway.solo.io
  resources:
  - virtualservices
  verbs:
  - get
  - list
  - watch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: opa-gloo-viewer
roleRef:
  kind: ClusterRole
  name: gloo-view
  apiGroup: rbac.authorization.k8s.io
subjects:
- kind: Group
  name: system:serviceaccounts:opa
  apiGroup: rbac.authorization.k8s.io
---
# Define role for OPA/kube-mgmt to update configmaps with policy status.
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: opa
  name: configmap-modifier
rules:
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["update", "patch"]
---
# Grant OPA/kube-mgmt role defined above.
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: opa
  name: opa-configmap-modifier
roleRef:
  kind: Role
  name: configmap-modifier
  apiGroup: rbac.authorization.k8s.io
subjects:
- kind: Group
  name: system:serviceaccounts:opa
  apiGroup: rbac.authorization.k8s.io
EOF

openssl genrsa -out ca.key 2048
openssl req -x509 -new -nodes -key ca.key -days 100000 -out ca.crt -subj "/CN=admission_ca"

cat >server.conf <<EOF
[req]
req_extensions = v3_req
distinguished_name = req_distinguished_name
[req_distinguished_name]
[ v3_req ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = clientAuth, serverAuth
EOF

openssl genrsa -out server.key 2048
openssl req -new -key server.key -out server.csr -subj "/CN=opa.opa.svc" -config server.conf
openssl x509 -req -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt -days 100000 -extensions v3_req -extfile server.conf

kubectl --namespace=opa create secret tls opa-server --cert=server.crt --key=server.key

kubectl --namespace=opa apply -f - <<EOF
kind: Service
apiVersion: v1
metadata:
  name: opa
  namespace: opa
spec:
  selector:
    app: opa
  ports:
  - name: https
    protocol: TCP
    port: 443
    targetPort: 443
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: opa
  namespace: opa
  name: opa
spec:
  replicas: 1
  selector:
    matchLabels:
      app: opa
  template:
    metadata:
      labels:
        app: opa
      name: opa
    spec:
      containers:
        # WARNING: OPA is NOT running with an authorization policy configured. This
        # means that clients can read and write policies in OPA. If you are
        # deploying OPA in an insecure environment, be sure to configure
        # authentication and authorization on the daemon. See the Security page for
        # details: https://www.openpolicyagent.org/docs/security.html.
        - name: opa
          image: openpolicyagent/opa:0.13.2
          args:
            - "run"
            - "--server"
            - "--tls-cert-file=/certs/tls.crt"
            - "--tls-private-key-file=/certs/tls.key"
            - "--addr=0.0.0.0:443"
            - "--addr=http://127.0.0.1:8181"
          volumeMounts:
            - readOnly: true
              mountPath: /certs
              name: opa-server
          readinessProbe:
            httpGet:
              path: /health
              scheme: HTTPS
              port: 443
            initialDelaySeconds: 3
            periodSeconds: 5
          livenessProbe:
            httpGet:
              path: /health
              scheme: HTTPS
              port: 443
            initialDelaySeconds: 3
            periodSeconds: 5
        - name: kube-mgmt
          image: openpolicyagent/kube-mgmt:0.8
          args:
            - "--replicate-cluster=v1/namespaces"
            - "--replicate=gateway.solo.io/v1/virtualservices"
      volumes:
        - name: opa-server
          secret:
            secretName: opa-server
---
kind: ConfigMap
apiVersion: v1
metadata:
  name: opa-default-system-main
  namespace: opa
data:
  main: |
    package system

    import data.kubernetes.admission

    main = {
      "apiVersion": "admission.k8s.io/v1beta1",
      "kind": "AdmissionReview",
      "response": response,
    }

    default response = {"allowed": true}

    response = {
        "allowed": false,
        "status": {
            "reason": reason,
        },
    } {
        reason = concat(", ", admission.deny)
        reason != ""
    }
EOF

kubectl label ns kube-system openpolicyagent.org/webhook=ignore
kubectl label ns opa openpolicyagent.org/webhook=ignore

kubectl apply -f - <<EOF
kind: ValidatingWebhookConfiguration
apiVersion: admissionregistration.k8s.io/v1beta1
metadata:
  name: opa-validating-webhook
webhooks:
  - name: validating-webhook.openpolicyagent.org
    namespaceSelector:
      matchExpressions:
      - key: openpolicyagent.org/webhook
        operator: NotIn
        values:
        - ignore
    rules:
      - operations: ["CREATE", "UPDATE"]
        apiGroups: ["gateway.solo.io"]
        apiVersions: ["v1"]
        resources: ["virtualservices"]
    clientConfig:
      caBundle: $(cat ca.crt | base64 | tr -d '\n')
      service:
        namespace: opa
        name: opa
EOF

apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: default
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - matchers:
       - exact: /sample-route-1
      routeAction:
        single:
          upstream:
            name: default-petstore-8080
            namespace: gloo-system

apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: default
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - matchers:
       - exact: /sample-route-1
      routeAction:
        single:
          upstream:
            name: default-petstore-8080
            namespace: gloo-system
      options:
        prefixRewrite: /api/pets