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Using Custom RBAC resources
KubeDB (version 0.13.0 and higher) supports finer user control over role based access permissions provided to a Redis instance. This tutorial will show you how to use KubeDB to run Redis instance with custom RBAC resources.
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/redis folder in GitHub repository kubedb/docs.
Overview
KubeDB allows users to provide custom RBAC resources, namely, ServiceAccount, Role, and RoleBinding for Redis. This is provided via the spec.podTemplate.spec.serviceAccountName field in Redis crd. If this field is left empty, the KubeDB operator will create a service account name matching Redis crd name. Role and RoleBinding that provide necessary access permissions will also be generated automatically for this service account.
If a service account name is given, but there’s no existing service account by that name, the KubeDB operator will create one, and Role and RoleBinding that provide necessary access permissions will also be generated for this service account.
If a service account name is given, and there’s an existing service account by that name, the KubeDB operator will use that existing service account. Since this service account is not managed by KubeDB, users are responsible for providing necessary access permissions manually.
This guide will show you how to create custom Service Account, Role, and RoleBinding for a Redis instance named quick-postges to provide the bare minimum access permissions.
Custom RBAC for Redis
At first, let’s create a Service Acoount in demo namespace.
$ kubectl create serviceaccount -n demo my-custom-serviceaccount
serviceaccount/my-custom-serviceaccount created
It should create a service account.
$ kubectl get serviceaccount -n demo my-custom-serviceaccount -o yaml
apiVersion: v1
kind: ServiceAccount
metadata:
creationTimestamp: "2019-05-30T04:23:39Z"
name: my-custom-serviceaccount
namespace: demo
resourceVersion: "21657"
selfLink: /api/v1/namespaces/demo/serviceaccounts/myserviceaccount
uid: b2ec2b05-8292-11e9-8d10-080027a8b217
secrets:
- name: myserviceaccount-token-t8zxd
Now, we need to create a role that has necessary access permissions for the Redis instance named quick-redis.
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/redis/custom-rbac/rd-custom-role.yaml
role.rbac.authorization.k8s.io/my-custom-role created
Below is the YAML for the Role we just created.
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
name: my-custom-role
namespace: demo
rules:
- apiGroups:
- policy
resourceNames:
- redis-db
resources:
- podsecuritypolicies
verbs:
- use
This permission is required for Redis pods running on PSP enabled clusters.
Now create a RoleBinding to bind this Role with the already created service account.
$ kubectl create rolebinding my-custom-rolebinding --role=my-custom-role --serviceaccount=demo:my-custom-serviceaccount --namespace=demo
rolebinding.rbac.authorization.k8s.io/my-custom-rolebinding created
It should bind my-custom-role and my-custom-serviceaccount successfully.
$ kubectl get rolebinding -n demo my-custom-rolebinding -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
name: my-custom-rolebinding
namespace: demo
resourceVersion: "1405"
selfLink: /apis/rbac.authorization.k8s.io/v1/namespaces/demo/rolebindings/my-custom-rolebinding
uid: 123afc02-8297-11e9-8d10-080027a8b217
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: my-custom-role
subjects:
- kind: ServiceAccount
name: my-custom-serviceaccount
namespace: demo
Now, create a Redis crd specifying spec.podTemplate.spec.serviceAccountName field to my-custom-serviceaccount.
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/redis/custom-rbac/rd-custom-db.yaml
redis.kubedb.com/quick-redis created
Below is the YAML for the Redis crd we just created.
apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
name: quick-redis
namespace: demo
spec:
version: "4.0-v2"
storageType: Durable
storage:
podTemplate:
spec:
serviceAccountName: my-custom-serviceaccount
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: DoNotTerminate
Now, wait a few minutes. the KubeDB operator will create necessary PVC, statefulset, services, secret etc. If everything goes well, we should see that a pod with the name quick-redis-0 has been created.
Check that the statefulset’s pod is running
$ kubectl get pod -n demo quick-redis-0
NAME READY STATUS RESTARTS AGE
quick-redis-0 1/1 Running 0 14m
Check the pod’s log to see if the database is ready
$ kubectl logs -f -n demo quick-redis-0
1:C 10 Jun 04:32:25.537 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1:C 10 Jun 04:32:25.537 # Redis version=4.0.11, bits=64, commit=00000000, modified=0, pid=1, just started
1:C 10 Jun 04:32:25.537 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
1:M 10 Jun 04:32:25.537 * Running mode=standalone, port=6379.
1:M 10 Jun 04:32:25.537 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1:M 10 Jun 04:32:25.537 # Server initialized
1:M 10 Jun 04:32:25.537 * Ready to accept connections
Once we see Ready to accept connections in the log, the database is ready.
Reusing Service Account
An existing service account can be reused in another Redis instance. No new access permission is required to run the new Redis instance.
Now, create Redis crd minute-redis using the existing service account name my-custom-serviceaccount in the spec.podTemplate.spec.serviceAccountName field.
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/redis/custom-rbac/rd-custom-db-two.yaml
redis.kubedb.com/quick-redis created
Below is the YAML for the Redis crd we just created.
apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
name: minute-redis
namespace: demo
spec:
version: "4.0-v2"
storageType: Durable
storage:
podTemplate:
spec:
serviceAccountName: my-custom-serviceaccount
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: DoNotTerminate
Now, wait a few minutes. the KubeDB operator will create necessary PVC, statefulset, services, secret etc. If everything goes well, we should see that a pod with the name minute-redis-0 has been created.
Check that the statefulset’s pod is running
$ kubectl get pod -n demo minute-redis-0
NAME READY STATUS RESTARTS AGE
minute-redis-0 1/1 Running 0 14m
Check the pod’s log to see if the database is ready
$ kubectl logs -f -n demo minute-redis-0
1:C 10 Jun 04:32:25.537 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
1:C 10 Jun 04:32:25.537 # Redis version=4.0.11, bits=64, commit=00000000, modified=0, pid=1, just started
1:C 10 Jun 04:32:25.537 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
1:M 10 Jun 04:32:25.537 * Running mode=standalone, port=6379.
1:M 10 Jun 04:32:25.537 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1:M 10 Jun 04:32:25.537 # Server initialized
1:M 10 Jun 04:32:25.537 * Ready to accept connections
Ready to accept connections in the log signifies that the database is running successfully.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl patch -n demo rd/quick-redis -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo rd/quick-redis
kubectl patch -n demo rd/minute-redis -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo rd/minute-redis
kubectl delete -n demo role my-custom-role
kubectl delete -n demo rolebinding my-custom-rolebinding
kubectl delete sa -n demo my-custom-serviceaccount
kubectl delete ns demo
If you would like to uninstall the KubeDB operator, please follow the steps here.
Next Steps
- Quickstart Redis with KubeDB Operator.
- Monitor your Redis instance with KubeDB using out-of-the-box Prometheus operator.
- Monitor your Redis instance with KubeDB using out-of-the-box builtin-Prometheus.
- Use private Docker registry to deploy Redis with KubeDB.
- Use kubedb cli to manage databases like kubectl for Kubernetes.
- Detail concepts of Redis object.
- Want to hack on KubeDB? Check our contribution guidelines.