Overview
KubeDB is the Kubernetes Native Database Management Solution which simplifies and automates routine database tasks such as Provisioning, Monitoring, Upgrading, Patching, Scaling, Volume Expansion, Backup, Recovery, Failure detection, and Repair for various popular databases on private and public clouds. The databases that KubeDB supports are Redis, PostgreSQL, MySQL, MongoDB, MariaDB, Elasticsearch, ProxySQL, Percona XtraDB, Memcached and PgBouncer. You can find the guides to all the supported databases here . In this tutorial we will deploy and manage Redis in Sentinel Mode in Google Kubernetes Engine (GKE). We will cover the following steps:
- Install KubeDB
- Deploy Redis Sentinel
- Deploy Redis Clustered Database
- Horizontal Scaling of Redis Sentinel
Install KubeDB
We will follow the steps to install KubeDB.
Get Cluster ID
We need the cluster ID to get the KubeDB License. To get cluster ID we can run the following command:
$ kubectl get ns kube-system -o jsonpath='{.metadata.uid}'
8e336615-0dbb-4ae8-b72f-2e7ec34c399d
Get License
Go to Appscode License Server to get the license.txt file. For this tutorial, we will use KubeDB Enterprise Edition.
Install KubeDB
We will use helm to install KubeDB. Please install helm here
if it is not already installed.
Now, let’s install KubeDB.
$ helm repo add appscode https://charts.appscode.com/stable/
$ helm repo update
$ helm search repo appscode/kubedb
NAME CHART VERSION APP VERSION DESCRIPTION
appscode/kubedb v2023.01.31 v2023.01.31 KubeDB by AppsCode - Production ready databases...
appscode/kubedb-autoscaler v0.16.0 v0.16.0 KubeDB Autoscaler by AppsCode - Autoscale KubeD...
appscode/kubedb-catalog v2023.01.31 v2023.01.31 KubeDB Catalog by AppsCode - Catalog for databa...
appscode/kubedb-community v0.24.2 v0.24.2 KubeDB Community by AppsCode - Community featur...
appscode/kubedb-crds v2023.01.31 v2023.01.31 KubeDB Custom Resource Definitions
appscode/kubedb-dashboard v0.7.0 v0.7.0 KubeDB Dashboard by AppsCode
appscode/kubedb-enterprise v0.11.2 v0.11.2 KubeDB Enterprise by AppsCode - Enterprise feat...
appscode/kubedb-grafana-dashboards v2023.01.31 v2023.01.31 A Helm chart for kubedb-grafana-dashboards by A...
appscode/kubedb-metrics v2023.01.31 v2023.01.31 KubeDB State Metrics
appscode/kubedb-ops-manager v0.18.0 v0.18.0 KubeDB Ops Manager by AppsCode - Enterprise fea...
appscode/kubedb-opscenter v2023.01.31 v2023.01.31 KubeDB Opscenter by AppsCode
appscode/kubedb-provisioner v0.31.0 v0.31.0 KubeDB Provisioner by AppsCode - Community feat...
appscode/kubedb-schema-manager v0.7.0 v0.7.0 KubeDB Schema Manager by AppsCode
appscode/kubedb-ui v2022.06.14 0.3.26 A Helm chart for Kubernetes
appscode/kubedb-ui-server v2021.12.21 v2021.12.21 A Helm chart for kubedb-ui-server by AppsCode
appscode/kubedb-webhook-server v0.7.0 v0.7.0 KubeDB Webhook Server by AppsCode
# Install KubeDB Enterprise operator chart
$ helm install kubedb appscode/kubedb \
--version v2023.01.31 \
--namespace kubedb --create-namespace \
--set kubedb-provisioner.enabled=true \
--set kubedb-ops-manager.enabled=true \
--set kubedb-autoscaler.enabled=true \
--set kubedb-dashboard.enabled=true \
--set kubedb-schema-manager.enabled=true \
--set-file global.license=/path/to/the/license.txt
Let’s verify the installation:
$ watch kubectl get pods --all-namespaces -l "app.kubernetes.io/instance=kubedb"
NAMESPACE NAME READY STATUS RESTARTS AGE
kubedb kubedb-kubedb-autoscaler-5d6cfbbdc6-mn7xn 1/1 Running 0 4m28s
kubedb kubedb-kubedb-dashboard-7f6d5c646b-kzmj4 1/1 Running 0 4m26s
kubedb kubedb-kubedb-ops-manager-57db88cc8-gmpb5 1/1 Running 0 4m28s
kubedb kubedb-kubedb-provisioner-f88f9d4f6-gq8nh 1/1 Running 0 4m28s
kubedb kubedb-kubedb-schema-manager-74447b985c-5qqhp 1/1 Running 0 4m27s
kubedb kubedb-kubedb-webhook-server-75dd594dcf-54lnw 1/1 Running 0 4m28s
We can list the CRD Groups that have been registered by the operator by running the following command:
$ kubectl get crd -l app.kubernetes.io/name=kubedb
NAME CREATED AT
elasticsearchautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
elasticsearchdashboards.dashboard.kubedb.com 2023-02-06T10:23:53Z
elasticsearches.kubedb.com 2023-02-06T10:23:52Z
elasticsearchopsrequests.ops.kubedb.com 2023-02-06T10:24:03Z
elasticsearchversions.catalog.kubedb.com 2023-02-06T10:15:28Z
etcds.kubedb.com 2023-02-06T10:23:53Z
etcdversions.catalog.kubedb.com 2023-02-06T10:15:29Z
mariadbautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
mariadbdatabases.schema.kubedb.com 2023-02-06T10:24:16Z
mariadbopsrequests.ops.kubedb.com 2023-02-06T10:24:49Z
mariadbs.kubedb.com 2023-02-06T10:23:54Z
mariadbversions.catalog.kubedb.com 2023-02-06T10:15:30Z
memcacheds.kubedb.com 2023-02-06T10:23:54Z
memcachedversions.catalog.kubedb.com 2023-02-06T10:15:31Z
mongodbautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
mongodbdatabases.schema.kubedb.com 2023-02-06T10:24:10Z
mongodbopsrequests.ops.kubedb.com 2023-02-06T10:24:07Z
mongodbs.kubedb.com 2023-02-06T10:23:55Z
mongodbversions.catalog.kubedb.com 2023-02-06T10:15:32Z
mysqlautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
mysqldatabases.schema.kubedb.com 2023-02-06T10:23:58Z
mysqlopsrequests.ops.kubedb.com 2023-02-06T10:24:46Z
mysqls.kubedb.com 2023-02-06T10:23:58Z
mysqlversions.catalog.kubedb.com 2023-02-06T10:15:33Z
perconaxtradbautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
perconaxtradbopsrequests.ops.kubedb.com 2023-02-06T10:25:15Z
perconaxtradbs.kubedb.com 2023-02-06T10:23:59Z
perconaxtradbversions.catalog.kubedb.com 2023-02-06T10:15:34Z
pgbouncers.kubedb.com 2023-02-06T10:23:59Z
pgbouncerversions.catalog.kubedb.com 2023-02-06T10:15:35Z
postgresautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
postgresdatabases.schema.kubedb.com 2023-02-06T10:24:14Z
postgreses.kubedb.com 2023-02-06T10:24:00Z
postgresopsrequests.ops.kubedb.com 2023-02-06T10:24:59Z
postgresversions.catalog.kubedb.com 2023-02-06T10:15:36Z
proxysqlopsrequests.ops.kubedb.com 2023-02-06T10:25:05Z
proxysqls.kubedb.com 2023-02-06T10:24:01Z
proxysqlversions.catalog.kubedb.com 2023-02-06T10:15:37Z
publishers.postgres.kubedb.com 2023-02-06T10:25:25Z
redisautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
redises.kubedb.com 2023-02-06T10:24:02Z
redisopsrequests.ops.kubedb.com 2023-02-06T10:24:53Z
redissentinelautoscalers.autoscaling.kubedb.com 2023-02-06T10:23:49Z
redissentinelopsrequests.ops.kubedb.com 2023-02-06T10:25:21Z
redissentinels.kubedb.com 2023-02-06T10:24:03Z
redisversions.catalog.kubedb.com 2023-02-06T10:15:38Z
Deploy Redis Sentinel
Now we are going to deploy Redis sentinel using KubeDB. First, let’s create a Namespace in which we will deploy the database.
$ kubectl create ns demo
namespace/demo created
Here is the yaml of the Redis sentinel we are going to use:
apiVersion: kubedb.com/v1alpha2
kind: RedisSentinel
metadata:
name: sentinel
namespace: demo
spec:
version: 7.0.5
replicas: 3
storageType: Durable
storage:
resources:
requests:
storage: 1Gi
storageClassName: "standard"
accessModes:
- ReadWriteOnce
terminationPolicy: WipeOut
Let’s save this yaml configuration into sentinel.yaml
Then create the above Redis sentinel
$ kubectl create -f sentinel.yaml
redissentinel.kubedb.com/sentinel created
In this yaml,
- Here, we can see in the
spec.versionfield specifies the version of Redis. Here, we are using Redisversion 7.0.5. You can list the KubeDB supported versions of Redis by running$ kubectl get redisversionscommand. - Another field to notice is the
spec.storageTypefield. This can beDurableorEphemeraldepending on the requirements of the database to be persistent or not. - Lastly, the
spec.terminationPolicyfield is Wipeout means that the database will be deleted without restrictions. It can also be “Halt”, “Delete” and “DoNotTerminate”. Learn More about these HERE .
Let’s check the status of Redis sentinel,
$ kubectl get redissentinel -n demo
NAME VERSION STATUS AGE
redissentinel.kubedb.com/sentinel 7.0.5 Ready 7m9s
Deploy Redis Cluster
Now, we are going to deploy Redis cluster using KubeDB. Here is the yaml we are going to use,
apiVersion: kubedb.com/v1alpha2
kind: Redis
metadata:
name: redis
namespace: demo
spec:
version: 7.0.5
replicas: 3
sentinelRef:
name: sentinel
namespace: demo
mode: Sentinel
storageType: Durable
storage:
resources:
requests:
storage: 1Gi
storageClassName: "standard"
accessModes:
- ReadWriteOnce
terminationPolicy: WipeOut
Let’s save this yaml configuration into redis.yaml
Then create the above Redis CRD
$ kubectl apply -f redis.yaml
redis.kubedb.com/redis created
In this yaml,
- Here, we can see in the
spec.versionfield specifies the version of Redis. Here, we are using Redisversion 7.0.5. You can list the KubeDB supported versions of Redis by running$ kubectl get redisversionscommand. spec.sentinelRef.nameandspec.sentinelRef.namespacespecifies the sentinel instance which will monitor this Redis database.- Another field to notice is the
spec.storageTypefield. This can beDurableorEphemeraldepending on the requirements of the database to be persistent or not. - Lastly, the
spec.terminationPolicyfield is Wipeout means that the database will be deleted without restrictions. It can also be “Halt”, “Delete” and “DoNotTerminate”. Learn More about these HERE .
Once these are handled correctly you will see that the following are created:
$ kubectl get all -n demo
NAME READY STATUS RESTARTS AGE
pod/redis-0 2/2 Running 0 4m20s
pod/redis-1 2/2 Running 0 3m54s
pod/redis-2 2/2 Running 0 92s
pod/sentinel-0 1/1 Running 0 19m
pod/sentinel-1 1/1 Running 0 19m
pod/sentinel-2 1/1 Running 0 14m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/redis ClusterIP 10.8.2.133 <none> 6379/TCP 4m23s
service/redis-pods ClusterIP None <none> 6379/TCP 4m24s
service/redis-standby ClusterIP 10.8.9.240 <none> 6379/TCP 4m23s
service/sentinel ClusterIP 10.8.6.95 <none> 26379/TCP 19m
service/sentinel-pods ClusterIP None <none> 26379/TCP 19m
NAME READY AGE
statefulset.apps/redis 3/3 4m26s
statefulset.apps/sentinel 3/3 19m
NAME TYPE VERSION AGE
appbinding.appcatalog.appscode.com/redis kubedb.com/redis 7.0.5 4m29s
appbinding.appcatalog.appscode.com/sentinel kubedb.com/redissentinel 7.0.5 19m
NAME VERSION STATUS AGE
redissentinel.kubedb.com/sentinel 7.0.5 Ready 20m
NAME VERSION STATUS AGE
redis.kubedb.com/redis 7.0.5 Ready 4m52s
Let’s check if the database is ready to use,
$ kubectl get redis -n demo
NAME VERSION STATUS AGE
redis 7.0.5 Ready 5m49s
We have successfully deployed Redis sentinel in GKE.
Accessing Sentinel Through CLI
In this section, We will exec into the sentinel pod and show you that it is continuously monitoring the Redis database,
kc exec -it -n demo sentinel-0 -- bash
Defaulted container "redissentinel" out of: redissentinel, sentinel-init (init)
root@sentinel-0:/data# redis-cli -p 26379
127.0.0.1:26379>
127.0.0.1:26379> sentinel masters
1) 1) "name"
2) "demo/redis"
3) "ip"
4) "redis-0.redis-pods.demo.svc"
5) "port"
6) "6379"
7) "runid"
8) "d927e06b07b8bf7140cff0ceb82b77d092b82a45"
9) "flags"
10) "master"
11) "link-pending-commands"
12) "0"
13) "link-refcount"
14) "1"
15) "last-ping-sent"
16) "0"
17) "last-ok-ping-reply"
18) "513"
19) "last-ping-reply"
20) "513"
21) "down-after-milliseconds"
22) "5000"
23) "info-refresh"
24) "4395"
25) "role-reported"
26) "master"
27) "role-reported-time"
28) "936584"
29) "config-epoch"
30) "0"
31) "num-slaves"
32) "2"
33) "num-other-sentinels"
34) "2"
35) "quorum"
36) "2"
37) "failover-timeout"
38) "5000"
39) "parallel-syncs"
40) "1"
127.0.0.1:26379> exit
Horizontal Scaling of Redis Sentinel
Scale Up Replicas
Here, we are going to scale up the replicas of the Redis sentinel to meet the desired number of replicas after scaling.
Before applying Horizontal Scaling, let’s check the current number of replicas,
$ kubectl get redissentinel -n demo sentinel -o json | jq '.spec.replicas'
3
Create RedisSentinelOpsRequest
In order to scale up the replicas, we have to create a RedisSentinelOpsRequest CR with our desired replicas. Let’s create it using this following yaml,
apiVersion: ops.kubedb.com/v1alpha1
kind: RedisSentinelOpsRequest
metadata:
name: horizontal-scale-up
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: sentinel
horizontalScaling:
replicas: 5
Here,
spec.databaseRef.namespecifies that we are performing horizontal scaling operation onsentinel.spec.typespecifies that we are performingHorizontalScalingon our database.spec.horizontalScaling.replicasspecifies the desired replicas after scaling.
Let’s save this yaml configuration into horizontal-scale-up.yaml and apply it,
$ kubectl apply -f horizontal-scale-up.yaml
redissentinelopsrequest.ops.kubedb.com/horizontal-scale-up created
Let’s wait for RedisSentinelOpsRequest STATUS to be Successful. Run the following command to watch RedisSentinelOpsRequest CR,
$ watch kubectl get redissentinelopsrequest -n demo
NAME TYPE STATUS AGE
horizontal-scale-up HorizontalScaling Successful 42s
We can see from the above output that the RedisSentinelOpsRequest has succeeded. Now, we are going to verify the number of replicas,
$ kubectl get redissentinel -n demo sentinel -o json | jq '.spec.replicas'
5
From all the above outputs we can see that the replicas of the sentinel is now increased to 5. That means we have successfully scaled up the Redis Sentinel.
Scale Down Replicas
Here, we are going to scale down the replicas of the Redis sentinel to meet the desired number of replicas after scaling.
Create RedisSentinelOpsRequest
In order to scale down the replicas, we need to create a RedisSentinelOpsRequest CR with our desired replicas. Let’s create it using this yaml,
apiVersion: ops.kubedb.com/v1alpha1
kind: RedisSentinelOpsRequest
metadata:
name: horizontal-scale-down
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: sentinel
horizontalScaling:
replicas: 3
Here,
spec.databaseRef.namespecifies that we are performing horizontal scaling operation onsentinel.spec.typespecifies that we are performingHorizontalScalingon our database.spec.horizontalScaling.replicasspecifies the desired replicas after scaling.
Let’s save this yaml configuration into horizontal-scale-down.yaml and apply it,
$ kubectl apply -f horizontal-scale-down.yaml
redissentinelopsrequest.ops.kubedb.com/horizontal-scale-down created
Let’s wait for RedisSentinelOpsRequest STATUS to be Successful. Run the following command to watch RedisSentinelOpsRequest CR,
$ watch kubectl get RedisSentinelOpsRequest -n demo
NAME TYPE STATUS AGE
horizontal-scale-down HorizontalScaling Successful 2m6s
We can see from the above output that the RedisSentinelOpsRequest has succeeded. Now, we are going to verify the number of replicas,
$ kubectl get redissentinel -n demo sentinel -o json | jq '.spec.replicas'
3
From all the above outputs we can see that the replicas of the Redis sentinel is decreased to 3. That means we have successfully scaled down the Redis sentinel.
We have made an in depth video on Redis Sentinel Ops Requests - Day 2 Lifecycle Management for Redis Sentinel Using KubeDB. You can have a look into the video below:
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