New to KubeDB? Please start here.
Initialize Redis using Script
This tutorial will show you how to use KubeDB to initialize a Redis database with shell or lua script.
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
demothroughout this tutorial.$ kubectl create ns demo namespace/demo created
Note: The yaml files used in this tutorial are stored in docs/examples/redis folder in GitHub repository kubedb/docs.
Prepare Initialization Scripts
Redis supports initialization with .sh and .lua files. In this tutorial, we will use init.sh script to insert data inside kubedb DB.
We will use a ConfigMap as script source. You can use any Kubernetes supported volume as script source.
At first, we will create a ConfigMap from init.sh file. Then, we will provide this ConfigMap as script source in init.script of Redis crd spec.
Let’s create a ConfigMap with initialization script,
$ kubectl create configmap -n demo rd-init-script --from-literal=init.sh="redis-cli set hello world"
configmap/rd-init-script created
Create a Redis database with Init-Script
Below is the Redis object created in this tutorial.
apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
name: rd-init-script
namespace: demo
spec:
version: 7.2.3
disableAuth: false
storageType: Durable
init:
script:
projected:
sources:
- configMap:
name: redis-init-script
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.8.21/docs/examples/redis/initialization/demo-1.yaml
redis.kubedb.com/rd-init-script created
Here,
spec.init.scriptspecifies a script source used to initialize the database before database server starts. Bash script with.shextension and lua script with.luaextension are supported.
KubeDB operator watches for Redis objects using Kubernetes api. When a Redis object is created, KubeDB operator will create a new PetSet and a Service with the matching Redis object name. KubeDB operator will also create a governing service for PetSets with the name <redis-crd-name>-gvr, if one is not already present. No Redis specific RBAC roles are required for RBAC enabled clusters.
$ kubectl describe rd -n demo rd-init-script
Name: rd-init-script
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: kubedb.com/v1alpha2
Kind: Redis
Metadata:
Creation Timestamp: 2024-08-06T05:59:40Z
Finalizers:
kubedb.com
Generation: 3
Resource Version: 133452
UID: ce6268b0-82b8-4ee5-a8fb-a6d2e1550a66
Spec:
Allowed Schemas:
Namespaces:
From: Same
Auth Secret:
Name: rd-init-script-auth
Auto Ops:
Coordinator:
Resources:
Health Checker:
Failure Threshold: 1
Period Seconds: 10
Timeout Seconds: 10
Init:
Initialized: true
Script:
Projected:
Sources:
Config Map:
Name: redis-init-script
Mode: Standalone
Pod Template:
Controller:
Metadata:
Spec:
Affinity:
Pod Anti Affinity:
Preferred During Scheduling Ignored During Execution:
Pod Affinity Term:
Label Selector:
Match Labels:
app.kubernetes.io/instance: rd-init-script
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: redises.kubedb.com
Namespaces:
demo
Topology Key: kubernetes.io/hostname
Weight: 100
Pod Affinity Term:
Label Selector:
Match Labels:
app.kubernetes.io/instance: rd-init-script
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: redises.kubedb.com
Namespaces:
demo
Topology Key: failure-domain.beta.kubernetes.io/zone
Weight: 50
Container Security Context:
Allow Privilege Escalation: false
Capabilities:
Drop:
ALL
Run As Group: 999
Run As Non Root: true
Run As User: 999
Seccomp Profile:
Type: RuntimeDefault
Resources:
Limits:
Memory: 1Gi
Requests:
Cpu: 500m
Memory: 1Gi
Security Context:
Fs Group: 999
Service Account Name: rd-init-script
Replicas: 1
Storage:
Access Modes:
ReadWriteOnce
Resources:
Requests:
Storage: 1Gi
Storage Class Name: standard
Storage Type: Durable
Termination Policy: WipeOut
Version: 7.2.3
Status:
Conditions:
Last Transition Time: 2024-08-06T05:59:40Z
Message: The KubeDB operator has started the provisioning of Redis: demo/rd-init-script
Reason: DatabaseProvisioningStartedSuccessfully
Status: True
Type: ProvisioningStarted
Last Transition Time: 2024-08-06T05:59:49Z
Message: All desired replicas are ready.
Reason: AllReplicasReady
Status: True
Type: ReplicaReady
Last Transition Time: 2024-08-06T06:00:22Z
Message: The Redis: demo/rd-init-script is ready.
Observed Generation: 3
Reason: ReadinessCheckSucceeded
Status: True
Type: Ready
Last Transition Time: 2024-08-06T06:00:32Z
Message: The Redis: demo/rd-init-script is accepting rdClient requests.
Observed Generation: 3
Reason: DatabaseAcceptingConnectionRequest
Status: True
Type: AcceptingConnection
Last Transition Time: 2024-08-06T06:00:15Z
Message: The Redis: demo/rd-init-script is successfully provisioned.
Observed Generation: 2
Reason: DatabaseSuccessfullyProvisioned
Status: True
Type: Provisioned
Observed Generation: 2
Phase: Ready
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Successful 82s KubeDB Operator Successfully created governing service
Normal Successful 82s KubeDB Operator Successfully created Service
Normal Successful 79s KubeDB Operator Successfully created appbinding
$ kubectl get petset -n demo
NAME READY AGE
rd-init-script 1/1 30s
$ kubectl get pvc -n demo
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
data-rd-init-script-0 Bound pvc-31dbab22-09af-4eeb-b032-1df287d9e579 1Gi RWO standard 2m17s
$ kubectl get pv -n demo
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
pvc-31dbab22-09af-4eeb-b032-1df287d9e579 1Gi RWO Delete Bound demo/data-rd-init-script-0 standard 2m37s
$ kubectl get service -n demo
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
rd-init-script ClusterIP 10.96.3.28 <none> 6379/TCP 3m11s
rd-init-script-pods ClusterIP None <none> 6379/TCP 3m11s
KubeDB operator sets the status.phase to Ready once the database is successfully created. Run the following command to see the modified Redis object:
$ kubectl get rd -n demo rd-init-script -o yaml
apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"kubedb.com/v1alpha2","kind":"Redis","metadata":{"annotations":{},"name":"rd-init-script","namespace":"demo"},"spec":{"disableAuth":false,"init":{"script":{"projected":{"sources":[{"configMap":{"name":"redis-init-script"}}]}}},"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","terminationPolicy":"WipeOut","version":"7.2.3"}}
creationTimestamp: "2024-08-06T05:59:40Z"
finalizers:
- kubedb.com
generation: 3
name: rd-init-script
namespace: demo
resourceVersion: "133452"
uid: ce6268b0-82b8-4ee5-a8fb-a6d2e1550a66
spec:
allowedSchemas:
namespaces:
from: Same
authSecret:
name: rd-init-script-auth
autoOps: {}
coordinator:
resources: {}
healthChecker:
failureThreshold: 1
periodSeconds: 10
timeoutSeconds: 10
init:
initialized: true
script:
projected:
sources:
- configMap:
name: redis-init-script
mode: Standalone
podTemplate:
controller: {}
metadata: {}
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: rd-init-script
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: redises.kubedb.com
namespaces:
- demo
topologyKey: kubernetes.io/hostname
weight: 100
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: rd-init-script
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: redises.kubedb.com
namespaces:
- demo
topologyKey: failure-domain.beta.kubernetes.io/zone
weight: 50
containerSecurityContext:
allowPrivilegeEscalation: false
capabilities:
drop:
- ALL
runAsGroup: 999
runAsNonRoot: true
runAsUser: 999
seccompProfile:
type: RuntimeDefault
resources:
limits:
memory: 1Gi
requests:
cpu: 500m
memory: 1Gi
securityContext:
fsGroup: 999
serviceAccountName: rd-init-script
replicas: 1
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: standard
storageType: Durable
terminationPolicy: WipeOut
version: 7.2.3
status:
conditions:
- lastTransitionTime: "2024-08-06T05:59:40Z"
message: 'The KubeDB operator has started the provisioning of Redis: demo/rd-init-script'
reason: DatabaseProvisioningStartedSuccessfully
status: "True"
type: ProvisioningStarted
- lastTransitionTime: "2024-08-06T05:59:49Z"
message: All desired replicas are ready.
reason: AllReplicasReady
status: "True"
type: ReplicaReady
- lastTransitionTime: "2024-08-06T06:00:22Z"
message: 'The Redis: demo/rd-init-script is ready.'
observedGeneration: 3
reason: ReadinessCheckSucceeded
status: "True"
type: Ready
- lastTransitionTime: "2024-08-06T06:00:32Z"
message: 'The Redis: demo/rd-init-script is accepting rdClient requests.'
observedGeneration: 3
reason: DatabaseAcceptingConnectionRequest
status: "True"
type: AcceptingConnection
- lastTransitionTime: "2024-08-06T06:00:15Z"
message: 'The Redis: demo/rd-init-script is successfully provisioned.'
observedGeneration: 2
reason: DatabaseSuccessfullyProvisioned
status: "True"
type: Provisioned
observedGeneration: 2
phase: Ready
Please note that KubeDB operator has created a new Secret called rd-init-script-auth (format: {redis-object-name}-auth) for storing the password for Redis superuser. This secret contains a username key which contains the username for Redis superuser and a password key which contains the password for Redis superuser.
If you want to use an existing secret please specify that when creating the Redis object using spec.authSecret.name. While creating this secret manually, make sure the secret contains these two keys containing data username and password.
$ kubectl get secrets -n demo rd-init-script-auth -o yaml
apiVersion: v1
data:
password: STRMTl9fVjJuaDlsdndhcg==
username: ZGVmYXVsdA==
kind: Secret
metadata:
creationTimestamp: "2024-08-06T05:59:40Z"
labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: rd-init-script
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: redises.kubedb.com
name: rd-init-script-auth
namespace: demo
resourceVersion: "133291"
uid: ece22594-6c5f-4428-ac0f-5f2d2690785f
type: kubernetes.io/basic-auth
Now, you can connect to this database through redis cli. In this tutorial, we are connecting to the Redis server from inside the pod.
$ kubectl get secrets -n demo rd-init-script-auth -o jsonpath='{.data.\username}' | base64 -d
default
$ kubectl get secrets -n demo rd-init-script-auth -o jsonpath='{.data.\password}' | base64 -d
I4LN__V2nh9lvwar
$ kubectl exec -it rd-init-script-0 -n demo -- bash
Defaulted container "redis" out of: redis, redis-init (init)
redis@rd-init-script-0:/data$
redis@rd-init-script-0:/data$ redis-cli get hello
"world"
redis@rd-init-script-0:/data$ exit
exit
As you can see here, the initial script has successfully created a database named kubedb and inserted data into that database successfully.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl patch -n demo rd/rd-init-script -p '{"spec":{"deletionPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo rd/rd-init-script
kubectl delete ns demo
Next Steps
- Backup and Restore Redis databases using Stash.
- Initialize Redis with Script.
- Monitor your Redis database with KubeDB using out-of-the-box Prometheus operator.
- Monitor your Redis database with KubeDB using out-of-the-box builtin-Prometheus.
- Use private Docker registry to deploy Redis with KubeDB.
- Detail concepts of Redis object.
- Detail concepts of redisVersion object.
- Want to hack on KubeDB? Check our contribution guidelines.