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RBAC Permissions for Postgres
If RBAC is enabled in clusters, some PostgreSQL specific RBAC permissions are required. These permissions are required for Leader Election process of PostgreSQL clustering.
Here is the list of additional permissions required by StatefulSet of Postgres:
| Kubernetes Resource | Resource Names | Permission required |
|---|---|---|
| statefulsets | {postgres-name} | get |
| pods | list, patch | |
| pods/exec | create | |
| Postgreses | get | |
| configmaps | {postgres-name} | get, update, create |
Before You Begin
At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.
Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.
To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Note: YAML files used in this tutorial are stored in docs/examples/postgres folder in GitHub repository kubedb/docs.
Create a PostgreSQL database
Below is the Postgres object created in this tutorial.
apiVersion: kubedb.com/v1alpha2
kind: Postgres
metadata:
name: quick-postgres
namespace: demo
spec:
version: "13.2"
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: Delete
Create above Postgres object with following command
$ kubectl create -f https://github.com/kubedb/docs/raw/v2022.05.24/docs/examples/postgres/quickstart/quick-postgres.yaml
postgres.kubedb.com/quick-postgres created
When this Postgres object is created, KubeDB operator creates Role, ServiceAccount and RoleBinding with the matching PostgreSQL name and uses that ServiceAccount name in the corresponding StatefulSet.
Let’s see what KubeDB operator has created for additional RBAC permission
Role
KubeDB operator create a Role object quick-postgres in same namespace as Postgres object.
$ kubectl get role -n demo quick-postgres -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
creationTimestamp: "2022-05-31T05:20:19Z"
labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: quick-postgres
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: postgreses.kubedb.com
name: quick-postgres
namespace: demo
ownerReferences:
- apiVersion: kubedb.com/v1alpha2
blockOwnerDeletion: true
controller: true
kind: Postgres
name: quick-postgres
uid: c118d264-85b7-4140-bc3f-d459c58c0523
resourceVersion: "367334"
uid: e72f25a5-5945-4687-9e8f-8af33c1a6b13
rules:
- apiGroups:
- apps
resourceNames:
- quick-postgres
resources:
- statefulsets
verbs:
- get
- apiGroups:
- kubedb.com
resourceNames:
- quick-postgres
resources:
- postgreses
verbs:
- get
- apiGroups:
- ""
resources:
- pods
verbs:
- get
- list
- patch
- delete
- apiGroups:
- ""
resources:
- pods/exec
verbs:
- create
- apiGroups:
- ""
resources:
- secrets
verbs:
- get
- list
- apiGroups:
- ""
resources:
- configmaps
verbs:
- create
- get
- update
- apiGroups:
- policy
resourceNames:
- postgres-db
resources:
- podsecuritypolicies
verbs:
- use
ServiceAccount
KubeDB operator create a ServiceAccount object quick-postgres in same namespace as Postgres object.
$ kubectl get serviceaccount -n demo quick-postgres -o yaml
apiVersion: v1
kind: ServiceAccount
metadata:
creationTimestamp: "2022-05-31T05:20:19Z"
labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: quick-postgres
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: postgreses.kubedb.com
name: quick-postgres
namespace: demo
ownerReferences:
- apiVersion: kubedb.com/v1alpha2
blockOwnerDeletion: true
controller: true
kind: Postgres
name: quick-postgres
uid: c118d264-85b7-4140-bc3f-d459c58c0523
resourceVersion: "367333"
uid: 1a1db587-d5a6-4cfc-aa82-dc960b7e1f28
This ServiceAccount is used in StatefulSet created for Postgres object.
RoleBinding
KubeDB operator create a RoleBinding object quick-postgres in same namespace as Postgres object.
$ kubectl get rolebinding -n demo quick-postgres -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
creationTimestamp: "2022-05-31T05:20:19Z"
labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: quick-postgres
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: postgreses.kubedb.com
name: quick-postgres
namespace: demo
ownerReferences:
- apiVersion: kubedb.com/v1alpha2
blockOwnerDeletion: true
controller: true
kind: Postgres
name: quick-postgres
uid: c118d264-85b7-4140-bc3f-d459c58c0523
resourceVersion: "367335"
uid: 1fc9f872-8adc-4940-b93d-18f70bec38d5
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: quick-postgres
subjects:
- kind: ServiceAccount
name: quick-postgres
namespace: demo
This object binds Role quick-postgres with ServiceAccount quick-postgres.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl patch -n demo pg/quick-postgres -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo pg/quick-postgres
kubectl delete ns demo