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NamespaceConfig Configuration Examples

Here is a list of use cases in which the Namespace Configuration Controller can be useful:

  1. T-Shirt Sized Quotas
  2. Default Network Policy
  3. Defining the Overcommitment Ratio
  4. ServiceAccount with Special Permission
  5. Pod with Special Permissions

This examples are ported from the previous version of the namespace-configuration-operator and can be used also as guidelines on how to perform the CR conversion.

Examples will be deployed in the test-namespace-config (you can pick any other name):

oc new-project test-namespace-config

T-Shirt Sized Quotas

During the provisioning of the projects to dev teams some organizations start with T-shirt sized quotas. Here is an example of how this can be done with the Namespace Configuration Controller

apiVersion: redhatcop.redhat.io/v1alpha1
kind: NamespaceConfig
metadata:
  name: small-size
spec:
  labelSelector:
    matchLabels:
      size: small  
  templates:
  - objectTemplate: |  
      apiVersion: v1
      kind: ResourceQuota
      metadata:
        name: small-size
        namespace: {{ .Name }}  
      spec:
        hard:
          requests.cpu: "4"
          requests.memory: "2Gi"
---
apiVersion: redhatcop.redhat.io/v1alpha1
kind: NamespaceConfig
metadata:
  name: large-size
spec:
  labelSelector:
    matchLabels:
      size: large  
  templates:
  - objectTemplate: |
      apiVersion: v1
      kind: ResourceQuota
      metadata:
        name: large-size
        namespace: {{ .Name }}
      spec:
        hard:
          requests.cpu: "8"
          requests.memory: "4Gi"

We can test the above configuration as follows:

oc apply -f examples/namespace-config/tshirt-quotas.yaml
oc new-project large-project
oc label namespace large-project size=large
oc new-project small-project
oc label namespace small-project size=small

Default Network Policy

Network policy are like firewall rules. There can be some reasonable defaults. In most cases isolating one project from other projects is a good way to start. In OpenShift this is the default behavior of the multitenant SDN plugin. The configuration would be as follows:

apiVersion: redhatcop.redhat.io/v1alpha1
kind: NamespaceConfig
metadata:
  name: multitenant
spec:
  labelSelector:
    matchLabels:
      multitenant: "true"  
  templates:
  - objectTemplate: |
      apiVersion: networking.k8s.io/v1
      kind: NetworkPolicy
      metadata:
        name: allow-from-same-namespace
        namespace: {{ .Name }}
      spec:
        podSelector:
        ingress:
        - from:
          - podSelector: {}
  - objectTemplate:  |
      apiVersion: networking.k8s.io/v1
      kind: NetworkPolicy
      metadata:
        name: allow-from-default-namespace
        namespace: {{ .Name }}
      spec:
        podSelector:
        ingress:
        - from:
          - namespaceSelector:
              matchLabels:
                name: default

We can deploy it with the following commands:

oc apply -f examples/namespace-config/multitenant-networkpolicy.yaml
oc new-project multitenant-project
oc label namespace multitenant-project multitenant=true

Defining the Overcommitment Ratio

I don't personally use limit range much. I prefer to define quotas and let the developers decide if they need a few large pods or many small pods. That said limit range can still be useful to define the ratio between request and limit, which at the node level will determine the node overcommitment ratio. Here is how it can be done:

apiVersion: redhatcop.redhat.io/v1alpha1
kind: NamespaceConfig
metadata:
  name: overcommit-limitrange
spec:
  labelSelector:
    matchLabels:
      overcommit: "limited"  
  templates:
  - objectTemplate: |
      apiVersion: "v1"
      kind: "LimitRange"
      metadata:
        name: "overcommit-limits"
        namespace: {{ .Name }}
      spec:
        limits:
          - type: "Container"
            maxLimitRequestRatio:
              cpu: 100
              memory: 1

We can deploy it with the following commands:

oc apply -f examples/namespace-config/overcommit-limitrange.yaml
oc new-project overcommit-project
oc label namespace overcommit-project overcommit=limited

ServiceAccount with Special Permission

Another scenario is an application that needs to talk to the master API and needs specific permissions to do that. As an example, we are creating a service account with the registry-viewer and registry-editor accounts. Here is what we can do:

apiVersion: redhatcop.redhat.io/v1alpha1
kind: NamespaceConfig
metadata:
  name: special-sa
spec:
  labelSelector:
    matchLabels:
      special-sa: "true"
  templates:
  - objectTemplate: |
      apiVersion: v1
      kind: ServiceAccount
      metadata:
        name: special-sa
        namespace: {{ .Name }}
  - objectTemplate:  |
      apiVersion: rbac.authorization.k8s.io/v1
      kind: RoleBinding
      metadata:
        name: special-sa-registry-editor
        namespace: {{ .Name }}
      roleRef:
        apiGroup: rbac.authorization.k8s.io
        kind: ClusterRole
        name: registry-editor
      subjects:
      - kind: ServiceAccount
        name: special-sa
  - objectTemplate:  |
      apiVersion: rbac.authorization.k8s.io/v1
      kind: RoleBinding
      metadata:
        name: special-sa-registry-viewer
        namespace: {{ .Name }}
      roleRef:
        apiGroup: rbac.authorization.k8s.io
        kind: ClusterRole
        name: registry-viewer
      subjects:
      - kind: ServiceAccount
        name: special-sa

Here is how it can be deployed:

oc apply -f examples/namespace-config/serviceaccount-permissions.yaml
oc new-project special-sa
oc label namespace special-sa special-sa=true

Pod with Special Permissions

Another scenario is a pod that needs to run with special permissions, i.e. a custom PodSecurityPolicy, and we don't want to give permission to the dev team to grant PodSecurityPolicy permissions. In OpenShift SCCs have represented the PodSecurityPolicy since the beginning of the product. SCCs are not compatible with namespace-configuration-operator because of the way SCC profiles are granted to serviceaccounts. With PodSecurityPolicy, this grant is done simply with a RoleBinding object. Here is how this might work:

apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
  name: forbid-privileged-pods
spec:
  privileged: false
  seLinux:
    rule: RunAsAny
  supplementalGroups:
    rule: RunAsAny
  runAsUser:
    rule: RunAsAny
  fsGroup:
    rule: RunAsAny
  volumes:
  - '*'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: forbid-privileged-pods
rules:
- apiGroups: ['policy']
  resources: ['podsecuritypolicies']
  verbs:     ['use']
  resourceNames:
  - forbid-privileged-pods
---  
apiVersion: redhatcop.redhat.io/v1alpha1
kind: NamespaceConfig
metadata:
  name: unprivileged-pods
spec:
  labelSelector:
    matchLabels:
      unprivileged-pods: "true"
  templates:
  - objectTemplate: |
      apiVersion: v1
      kind: ServiceAccount
      metadata:
        name: unprivileged-pods
        namespace: {{ .Name }}
  - objectTemplate: |
      apiVersion: rbac.authorization.k8s.io/v1
      kind: RoleBinding
      metadata:
        name: unprivileged-pods-rb
        namespace: {{ .Name }}
      roleRef:
        apiGroup: rbac.authorization.k8s.io
        kind: ClusterRole
        name: forbid-privileged-pods
      subjects:
      - kind: ServiceAccount
        name: unprivileged-pods

Here is how this example can be run:

oc apply -f examples/namespace-config/special-pod.yaml
oc new-project special-pod
oc label namespace special-pod unprivileged-pods=true

Cleaning up

To clean up the previous example you can run the following:

oc delete -f examples/namespace-config/special-pod.yaml
oc delete -f examples/namespace-config/serviceaccount-permissions.yaml
oc delete -f examples/namespace-config/overcommit-limitrange.yaml
oc delete -f examples/namespace-config/multitenant-networkpolicy.yaml
oc delete -f examples/namespace-config/tshirt-quotas.yaml
oc delete project special-pod special-sa overcommit-project multitenant-project small-project large-project test-namespace-config