New to KubeDB? Please start here.
Redis QuickStart
This tutorial will show you how to use KubeDB to run a Redis database.
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 Minikube.
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. Run the following command to prepare your cluster for this tutorial:
$ kubectl create ns demo
namespace "demo" created
$ kubectl get ns
NAME STATUS AGE
default Active 45m
demo Active 10s
kube-public Active 45m
kube-system Active 45m
Note that the yaml files that are used in this tutorial, stored in docs/examples folder in GitHub repository kubedb/cli.
Create a Redis database
KubeDB implements a Redis CRD to define the specification of a Redis database. Below is the Redis object created in this tutorial.
apiVersion: kubedb.com/v1alpha1
kind: Redis
metadata:
name: redis-quickstart
namespace: demo
spec:
version: "4"
doNotPause: true
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Mi
$ kubedb create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-rc.0/docs/examples/redis/quickstart/demo-1.yaml
redis "redis-quickstart" created
Here,
spec.version is the version of Redis database. In this tutorial, a Redis 4 database is going to be created.spec.doNotPause tells KubeDB operator that if this object is deleted, it should be automatically reverted. This should be set to true for production databases to avoid accidental deletion.spec.storage specifies the StorageClass of PVC dynamically allocated to store data for this database. This storage spec will be passed to the StatefulSet created by KubeDB operator to run database pods. You can specify any StorageClass available in your cluster with appropriate resource requests. Since release 0.8.0-rc.0, a storage spec is required for Redis.
KubeDB operator watches for Redis objects using Kubernetes api. When a Redis object is created, KubeDB operator will create a new StatefulSet and a ClusterIP Service with the matching Redis object name. KubeDB operator will also create a governing service for StatefulSets with the name kubedb, if one is not already present. No Redis specific RBAC permission is required in RBAC enabled clusters.
$ kubedb get rd -n demo
NAME STATUS AGE
redis-quickstart Running 1m
$ kubedb describe rd -n demo redis-quickstart
Name: redis-quickstart
Namespace: demo
StartTimestamp: Mon, 12 Feb 2018 16:41:39 +0600
Status: Running
Volume:
StorageClass: standard
Capacity: 50Mi
Access Modes: RWO
StatefulSet:
Name: redis-quickstart
Replicas: 1 current / 1 desired
CreationTimestamp: Mon, 12 Feb 2018 16:41:41 +0600
Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: redis-quickstart
Type: ClusterIP
IP: 10.101.253.6
Port: db 6379/TCP
Events:
FirstSeen LastSeen Count From Type Reason Message
--------- -------- ----- ---- -------- ------ -------
1m 1m 1 Redis operator Normal Successful Successfully created StatefulSet
1m 1m 1 Redis operator Normal Successful Successfully created Redis
1m 1m 1 Redis operator Normal Successful Successfully created Service
$ kubectl get statefulset -n demo
NAME DESIRED CURRENT AGE
redis-quickstart 1 1 2m
$ kubectl get pvc -n demo
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
data-redis-quickstart-0 Bound pvc-4fbc09fb-0fe1-11e8-a2d6-08002751ae8c 50Mi RWO standard 2m
$ kubectl get pv -n demo
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-4fbc09fb-0fe1-11e8-a2d6-08002751ae8c 50Mi RWO Delete Bound demo/data-redis-quickstart-0 standard 3m
$ kubectl get service -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubedb ClusterIP None <none> <none> 3m
redis-quickstart ClusterIP 10.101.253.6 <none> 6379/TCP 3m
KubeDB operator sets the status.phase to Running once the database is successfully created. Run the following command to see the modified Redis object:
$ kubedb get rd -n demo redis-quickstart -o yaml
apiVersion: kubedb.com/v1alpha1
kind: Redis
metadata:
clusterName: ""
creationTimestamp: 2018-02-12T10:41:39Z
finalizers:
- kubedb.com
generation: 0
name: redis-quickstart
namespace: demo
resourceVersion: "46523"
selfLink: /apis/kubedb.com/v1alpha1/namespaces/demo/redises/redis-quickstart
uid: 4ecf9d7c-0fe1-11e8-a2d6-08002751ae8c
spec:
doNotPause: true
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Mi
storageClassName: standard
version: "4"
status:
creationTime: 2018-02-12T10:41:40Z
phase: Running
Now, you can connect to this database through redis-cli. In this tutorial, we are connecting to the Redis server from inside of pod.
$ kubectl exec -it redis-quickstart-0 -n demo sh
> redis-cli
127.0.0.1:6379> ping
PONG
#save data
127.0.0.1:6379> SET mykey "Hello"
OK
# view data
127.0.0.1:6379> GET mykey
"Hello"
127.0.0.1:6379> exit
Pause Database
KubeDB takes advantage of ValidationWebhook feature in Kubernetes 1.9.0 or later clusters to implement doNotPause feature. If admission webhook is enabled, It prevents user from deleting the database as long as the spec.doNotPause is set to true. Since the Redis object created in this tutorial has spec.doNotPause set to true, if you delete the Redis object, KubeDB operator will nullify the delete operation. You can see this below:
$ kubedb delete rd redis-quickstart -n demo
error: Redis "redis-quickstart" can't be paused. To continue delete, unset spec.doNotPause and retry.
Now, run kubedb edit rd redis-quickstart -n demo to set spec.doNotPause to false or remove this field (which default to false). Then if you delete the Redis object, KubeDB operator will delete the StatefulSet and its pods, but leaves the PVCs unchanged. In KubeDB parlance, we say that redis-quickstart Redis database has entered into dormant state. This is represented by KubeDB operator by creating a matching DormantDatabase object.
$ kubedb delete rd redis-quickstart -n demo
redis "redis-quickstart" deleted
$ kubedb get drmn -n demo redis-quickstart
NAME STATUS AGE
redis-quickstart Pausing 6s
$ kubedb get drmn -n demo redis-quickstart
NAME STATUS AGE
redis-quickstart Paused 10s
$ kubedb get drmn -n demo redis-quickstart -o yaml
apiVersion: kubedb.com/v1alpha1
kind: DormantDatabase
metadata:
clusterName: ""
creationTimestamp: 2018-02-12T10:48:07Z
finalizers:
- kubedb.com
generation: 0
labels:
kubedb.com/kind: Redis
name: redis-quickstart
namespace: demo
resourceVersion: "46767"
selfLink: /apis/kubedb.com/v1alpha1/namespaces/demo/dormantdatabases/redis-quickstart
uid: 360017bb-0fe2-11e8-a2d6-08002751ae8c
spec:
origin:
metadata:
creationTimestamp: null
name: redis-quickstart
namespace: demo
spec:
redis:
resources: {}
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 50Mi
storageClassName: standard
version: "4"
status:
creationTime: 2018-02-12T10:48:08Z
pausingTime: 2018-02-12T10:48:15Z
phase: Paused
Here,
spec.origin is the spec of the original spec of the original Redis object.status.phase points to the current database state Paused.
Resume Dormant Database
To resume the database from the dormant state, create same Redis object with same Spec.
In this tutorial, the dormant database can be resumed by creating original Redis object.
The below command will resume the DormantDatabase redis-quickstart.
$ kubedb create -f https://raw.githubusercontent.com/kubedb/cli/0.8.0-rc.0/docs/examples/redis/quickstart/demo-1.yaml
redis "redis-quickstart" created
WipeOut DormantDatabase
You can wipe out a DormantDatabase while deleting the objet by setting spec.wipeOut to true. KubeDB operator will delete any relevant resources of this Redis database (i.e, PVCs, Secrets).
$ kubedb delete rd redis-quickstart -n demo
redis "redis-quickstart" deleted
$ kubedb edit drmn -n demo redis-quickstart
apiVersion: kubedb.com/v1alpha1
kind: DormantDatabase
metadata:
name: redis-quickstart
namespace: demo
...
spec:
wipeOut: true
...
status:
phase: Paused
...
If spec.wipeOut is not set to true while deleting the dormantdatabase object, then only this object will be deleted and kubedb-operator won’t delete related Secrets, PVCs and Snapshots. So, user still can access the PVCs.
Delete DormantDatabase
As it is already discussed above, DormantDatabase can be deleted with or without wiping out the resources. To delete the dormantdatabase,
$ kubedb delete drmn redis-quickstart -n demo
dormantdatabase "redis-quickstart" deleted
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
$ kubectl patch -n demo rd/redis-quickstart -p '{"spec":{"doNotPause":false}}' --type="merge"
$ kubectl delete -n demo rd/redis-quickstart
$ kubectl patch -n demo drmn/redis-quickstart -p '{"spec":{"wipeOut":true}}' --type="merge"
$ kubectl delete -n demo drmn/redis-quickstart
$ kubectl delete ns demo
namespace "demo" deleted
Next Steps
