Private Namespace and Restricted RBAC¶

A non-admin type user typically does not have permissions for any cluster-scoped resources and only has read and/or write permissions to resources in one or more namespaces.

About this task

Note

All of the RBAC resources for managing non-admin type users, although they may apply to private namespaces, are created in kube-system such that only admin level users can manager non-admin type users, roles, and rolebindings.

The following example creates a non-admin service account called dave-user with read/write type access to a single private namespace (billing-dept-ns).

Note

The following example creates and uses ServiceAccounts as the user mechanism and subject for the rolebindings, however the procedure equally applies to user accounts defined in an external Windows Active Directory as the subject of the rolebindings.

Procedure

If it does not already exist, create a general user role defining restricted permissions for general users.

This is of the type ClusterRole so that it can be used in the context of any namespace when binding to a user.

Create the user role definition file.

% cat <<EOF > general-user-clusterrole.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  # "namespace" omitted since ClusterRoles are not namespaced
  name: general-user

rules:

# For the core API group (""), allow full access to all resource types
# EXCEPT for resource policies (limitranges and resourcequotas) only allow read access
- apiGroups: [""]
  resources: ["bindings", "configmaps", "endpoints", "events", "persistentvolumeclaims", "pods", "podtemplates", "replicationcontrollers", "secrets", "serviceaccounts", "services"]
  verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]
- apiGroups: [""]
  resources: [ "limitranges", "resourcequotas" ]
  verbs: ["get", "list"]

# Allow full access to all resource types of the following explicit list of apiGroups.
# Notable exceptions here are:
#     ApiGroup                      ResourceTypes
#     -------                       -------------
#     policy                        podsecuritypolicies, poddisruptionbudgets
#     networking.k8s.io             networkpolicies
#     admissionregistration.k8s.io  mutatingwebhookconfigurations, validatingwebhookconfigurations
#
- apiGroups: ["apps", "batch", "extensions", "autoscaling", "apiextensions.k8s.io", "rbac.authorization.k8s.io"]
  resources: ["*"]
  verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]

# Cert Manager API access
- apiGroups: ["cert-manager.io", "acme.cert-manager.io"]
  resources: ["*"]
  verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]

EOF

Apply the definition.

~(keystone_admin)$ kubectl apply -f general-user-cluster-role.yaml

Create the billing-dept-ns namespace, if it does not already exist.
```
~(keystone_admin)$ kubectl create namespace billing-dept-ns
```

Create both the dave-user service account and the namespace-scoped RoleBinding.

The RoleBinding binds the general-user role to the dave-user ServiceAccount for the billing-dept-ns namespace.

Create the account definition file.

% cat <<EOF > dave-user.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: dave-user
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: dave-user
  namespace: billing-dept-ns
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: general-user
subjects:
- kind: ServiceAccount
  name: dave-user
  namespace: kube-system
EOF

Apply the definition.
```
% kubectl apply -f dave-user.yaml
```

If the user requires use of the local docker registry, create an openstack user account for authenticating with the local docker registry.
1. If a project does not already exist for this user, create one.
```
% openstack project create billing-dept-ns
```
2. Create an openstack user in this project.
```
% openstack user create --password P@ssw0rd \
--project billing-dept-ns dave-user
```
  Note
  
  Substitute a password conforming to your password formatting rules for P@ssw0rd.
3. Create a secret containing these userid/password credentials for use as an ImagePullSecret
```
% kubectl create secret docker-registry registry-local-dave-user --docker-server=registry.local:9001 --docker-username=dave-user  --docker-password=P@ssw0rd --docker-email=noreply@windriver.com -n billing-dept-ns
```
dave-user can now push images to registry.local:9001/dave-user/ and use these images for pods by adding the secret above as an ImagePullSecret in the pod spec.

If the user requires the ability to create persistentVolumeClaims in his namespace, then execute the following commands to enable the rbd-provisioner in the user’s namespace.

Create an RBD namespaces configuration file.

% cat <<EOF > rbd-namespaces.yaml
classes:
- additionalNamespaces: [default, kube-public, billing-dept-ns]
  chunk_size: 64
  crush_rule_name: storage_tier_ruleset
  name: general
  pool_name: kube-rbdkube-system
  replication: 1
  userId: ceph-pool-kube-rbd
  userSecretName: ceph-pool-kube-rbd
EOF

Update the helm overrides.

~(keystone_admin)$ system helm-override-update --reuse-values --values rbd-namespaces.yaml \
platform-integ-apps rbd-provisioner kube-system

Apply the application.

~(keystone_admin)$ system application-apply platform-integ-apps

Monitor the system for the application-apply to finish
```
~(keystone_admin)$ system application-list
```

If this user requires the ability to use helm, do the following.

Create a ClusterRole for reading namespaces, if one does not already exist.

% cat <<EOF > namespace-reader-clusterrole.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: namespace-reader
rules:
- apiGroups: [""]
  resources: ["namespaces"]
  verbs: ["get", "watch", "list"]
EOF

Apply the configuration.

% kubectl apply -f namespace-reader-clusterrole.yaml

Create a RoleBinding for the tiller account of the user’s namespace.

Note

The tiller account of the user’s namespace must be named ‘tiller’. See StarlingX System Configuration: Configure Remote Helm Client for Non-Admin Users.

% cat <<EOF > read-namespaces-billing-dept-ns-tiller.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: read-namespaces-billing-dept-ns-tiller
subjects:
- kind: ServiceAccount
  name: tiller
  namespace: billing-dept-ns
roleRef:
  kind: ClusterRole
  name: namespace-reader
  apiGroup: rbac.authorization.k8s.io
EOF

Apply the configuration.

% kubectl apply -f read-namespaces-billing-dept-ns-tiller.yaml