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Autoscaling the Compute Resource of a Postgres Cluster Database
This guide will show you how to use KubeDB to auto-scale compute resources i.e. cpu and memory of a Postgres cluster database.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectlcommand-line tool must be configured to communicate with your cluster.Install
KubeDBCommunity, Ops-Manager and Autoscaler operator in your cluster following the steps here.Install
Metrics Serverfrom hereYou should be familiar with the following
KubeDBconcepts:
To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Autoscaling of Cluster Database
Here, we are going to deploy a Postgres Cluster using a supported version by KubeDB operator. Then we are going to apply PostgresAutoscaler to set up autoscaling.
Deploy Postgres Cluster
In this section, we are going to deploy a Postgres Cluster with version 16.1. Then, in the next section we will set up autoscaling for this database using PostgresAutoscaler CRD. Below is the YAML of the Postgres CR that we are going to create,
If you want to autoscale Postgres
Standalone, Just remove thespec.Replicasfrom the below yaml and rest of the steps are same.
apiVersion: kubedb.com/v1
kind: Postgres
metadata:
name: ha-postgres
namespace: demo
spec:
version: "16.1"
replicas: 3
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
podTemplate:
spec:
containers:
- name: postgres
resources:
requests:
cpu: "200m"
memory: "512Mi"
limits:
cpu: "200m"
memory: "512Mi"
deletionPolicy: WipeOut
Let’s create the Postgres CRO we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.11.8-rc.0/docs/examples/postgres/autoscaler/compute/ha-postgres.yaml
postgres.kubedb.com/ha-postgres created
Now, wait until ha-postgres has status Ready. i.e,
$ kubectl get postgres -n demo
NAME VERSION STATUS AGE
ha-postgres 16.1 Ready 14m
Let’s check the Pod containers resources,
$ kubectl get pod -n demo ha-postgres-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "200m",
"memory": "512Mi"
},
"requests": {
"cpu": "200m",
"memory": "512Mi"
}
}
Let’s check the Postgres resources,
$ kubectl get postgres -n demo ha-postgres -o json | jq '.spec.podTemplate.spec.resources'
{
"limits": {
"cpu": "200m",
"memory": "512Mi"
},
"requests": {
"cpu": "200m",
"memory": "512Mi"
}
}
You can see from the above outputs that the resources are same as the one we have assigned while deploying the postgres.
We are now ready to apply the PostgresAutoscaler CRO to set up autoscaling for this database.
Compute Resource Autoscaling
Here, we are going to set up compute resource autoscaling using a PostgresAutoscaler Object.
Create PostgresAutoscaler Object
In order to set up compute resource autoscaling for this database cluster, we have to create a PostgresAutoscaler CRO with our desired configuration. Below is the YAML of the PostgresAutoscaler object that we are going to create,
apiVersion: autoscaling.kubedb.com/v1alpha1
kind: PostgresAutoscaler
metadata:
name: pg-as-compute
namespace: demo
spec:
databaseRef:
name: ha-postgres
opsRequestOptions:
timeout: 3m
apply: IfReady
compute:
postgres:
trigger: "On"
podLifeTimeThreshold: 5m
resourceDiffPercentage: 20
minAllowed:
cpu: 250m
memory: 1Gi
maxAllowed:
cpu: 1
memory: 1Gi
containerControlledValues: "RequestsAndLimits"
controlledResources: ["cpu", "memory"]
Here,
spec.databaseRef.namespecifies that we are performing compute resource scaling operation onha-postgresdatabase.spec.compute.postgres.triggerspecifies that compute autoscaling is enabled for this database.spec.compute.postgres.podLifeTimeThresholdspecifies the minimum lifetime for at least one of the pod to initiate a vertical scaling.spec.compute.postgres.resourceDiffPercentagespecifies the minimum resource difference in percentage. The default is 10%. If the difference between current & recommended resource is less than ResourceDiffPercentage, Autoscaler Operator will ignore the updating.spec.compute.postgres.minAllowedspecifies the minimum allowed resources for the database.spec.compute.postgres.maxAllowedspecifies the maximum allowed resources for the database.spec.compute.postgres.controlledResourcesspecifies the resources that are controlled by the autoscaler.spec.compute.postgres.containerControlledValuesspecifies which resource values should be controlled. The default is “RequestsAndLimits”.spec.opsRequestOptions.applyhas two supported value :IfReady&Always. UseIfReadyif you want to process the opsReq only when the database is Ready. And useAlwaysif you want to process the execution of opsReq irrespective of the Database state.spec.opsRequestOptions.timeoutspecifies the maximum time for each step of the opsRequest(in seconds). If a step doesn’t finish within the specified timeout, the ops request will result in failure.
Let’s create the PostgresAutoscaler CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.11.8-rc.0/docs/examples/postgres/autoscaler/compute/pgas-compute.yaml
postgresautoscaler.autoscaling.kubedb.com/pg-as-compute created
Verify Autoscaling is set up successfully
Let’s check that the postgresautoscaler resource is created successfully,
$ kubectl get postgresautoscaler -n demo
NAME AGE
pg-as-compute 5m56s
$ kubectl describe postgresautoscaler pg-as-compute -n demo
Name: pg-as-compute
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: autoscaling.kubedb.com/v1alpha1
Kind: PostgresAutoscaler
Metadata:
Creation Timestamp: 2022-09-16T11:26:58Z
Generation: 1
Managed Fields:
API Version: autoscaling.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.:
f:kubectl.kubernetes.io/last-applied-configuration:
f:spec:
.:
f:compute:
.:
f:postgres:
.:
f:containerControlledValues:
f:controlledResources:
f:maxAllowed:
.:
f:cpu:
f:memory:
f:minAllowed:
.:
f:cpu:
f:memory:
f:podLifeTimeThreshold:
f:resourceDiffPercentage:
f:trigger:
f:databaseRef:
.:
f:name:
f:opsRequestOptions:
.:
f:apply:
f:timeout:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2022-09-16T11:26:58Z
API Version: autoscaling.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:status:
.:
f:checkpoints:
f:conditions:
f:vpas:
Manager: kubedb-autoscaler
Operation: Update
Subresource: status
Time: 2022-09-16T11:27:07Z
Resource Version: 846645
UID: 44bd46c3-bbc5-4c4a-aff4-00c7f84c6f58
Spec:
Compute:
Mariadb:
Container Controlled Values: RequestsAndLimits
Controlled Resources:
cpu
memory
Max Allowed:
Cpu: 1
Memory: 1Gi
Min Allowed:
Cpu: 250m
Memory: 1Gi
Pod Life Time Threshold: 5m0s
Resource Diff Percentage: 20
Trigger: On
Database Ref:
Name: ha-postgres
Ops Request Options:
Apply: IfReady
Timeout: 3m0s
Status:
Checkpoints:
Cpu Histogram:
Bucket Weights:
Index: 0
Weight: 10000
Index: 46
Weight: 555
Reference Timestamp: 2022-09-16T00:00:00Z
Total Weight: 2.648440345821337
First Sample Start: 2022-09-16T11:26:48Z
Last Sample Start: 2022-09-16T11:32:52Z
Last Update Time: 2022-09-16T11:33:02Z
Memory Histogram:
Bucket Weights:
Index: 1
Weight: 10000
Reference Timestamp: 2022-09-17T00:00:00Z
Total Weight: 1.391848625060675
Ref:
Container Name: md-coordinator
Vpa Object Name: ha-postgres
Total Samples Count: 19
Version: v3
Cpu Histogram:
Bucket Weights:
Index: 0
Weight: 10000
Index: 3
Weight: 556
Reference Timestamp: 2022-09-16T00:00:00Z
Total Weight: 2.648440345821337
First Sample Start: 2022-09-16T11:26:48Z
Last Sample Start: 2022-09-16T11:32:52Z
Last Update Time: 2022-09-16T11:33:02Z
Memory Histogram:
Reference Timestamp: 2022-09-17T00:00:00Z
Ref:
Container Name: postgres
Vpa Object Name: ha-postgres
Total Samples Count: 19
Version: v3
Conditions:
Last Transition Time: 2022-09-16T11:27:07Z
Message: Successfully created postgresOpsRequest demo/pgops-ha-postgres-6xc1kc
Observed Generation: 1
Reason: CreateOpsRequest
Status: True
Type: CreateOpsRequest
Vpas:
Conditions:
Last Transition Time: 2022-09-16T11:27:02Z
Status: True
Type: RecommendationProvided
Recommendation:
Container Recommendations:
Container Name: postgres
Lower Bound:
Cpu: 250m
Memory: 1Gi
Target:
Cpu: 250m
Memory: 1Gi
Uncapped Target:
Cpu: 25m
Memory: 262144k
Upper Bound:
Cpu: 1
Memory: 1Gi
Vpa Name: ha-postgres
Events: <none>
So, the postgresautoscaler resource is created successfully.
We can verify from the above output that status.vpas contains the RecommendationProvided condition to true. And in the same time, status.vpas.recommendation.containerRecommendations contain the actual generated recommendation.
Our autoscaler operator continuously watches the recommendation generated and creates an postgresopsrequest based on the recommendations, if the database pod resources are needed to scaled up or down.
Let’s watch the postgresopsrequest in the demo namespace to see if any postgresopsrequest object is created. After some time you’ll see that a postgresopsrequest will be created based on the recommendation.
$ kubectl get postgresopsrequest -n demo
NAME TYPE STATUS AGE
pgops-ha-postgres-6xc1kc VerticalScaling Progressing 7s
Let’s wait for the ops request to become successful.
$ kubectl get postgresopsrequest -n demo
NAME TYPE STATUS AGE
pgops-vpa-ha-postgres-z43wc8 VerticalScaling Successful 3m32s
We can see from the above output that the PostgresOpsRequest has succeeded. If we describe the PostgresOpsRequest we will get an overview of the steps that were followed to scale the database.
$ kubectl describe postgresopsrequest -n demo pgops-vpa-ha-postgres-z43wc8
Name: pgops-ha-postgres-6xc1kc
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: PostgresOpsRequest
Metadata:
Creation Timestamp: 2022-09-16T11:27:07Z
Generation: 1
Managed Fields:
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:ownerReferences:
.:
k:{"uid":"44bd46c3-bbc5-4c4a-aff4-00c7f84c6f58"}:
f:spec:
.:
f:apply:
f:databaseRef:
.:
f:name:
f:timeout:
f:type:
f:verticalScaling:
.:
f:postgres:
.:
f:limits:
.:
f:cpu:
f:memory:
f:requests:
.:
f:cpu:
f:memory:
Manager: kubedb-autoscaler
Operation: Update
Time: 2022-09-16T11:27:07Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-ops-manager
Operation: Update
Subresource: status
Time: 2022-09-16T11:27:07Z
Owner References:
API Version: autoscaling.kubedb.com/v1alpha1
Block Owner Deletion: true
Controller: true
Kind: PostgresAutoscaler
Name: pg-as-compute
UID: 44bd46c3-bbc5-4c4a-aff4-00c7f84c6f58
Resource Version: 846324
UID: c2b30107-c6d3-44bb-adf3-135edc5d615b
Spec:
Apply: IfReady
Database Ref:
Name: ha-postgres
Timeout: 2m0s
Type: VerticalScaling
Vertical Scaling:
Mariadb:
Limits:
Cpu: 250m
Memory: 1Gi
Requests:
Cpu: 250m
Memory: 1Gi
Status:
Conditions:
Last Transition Time: 2022-09-16T11:27:07Z
Message: Controller has started to Progress the PostgresOpsRequest: demo/pgops-ha-postgres-6xc1kc
Observed Generation: 1
Reason: OpsRequestProgressingStarted
Status: True
Type: Progressing
Last Transition Time: 2022-09-16T11:30:42Z
Message: Successfully restarted Postgres pods for PostgresOpsRequest: demo/pgops-ha-postgres-6xc1kc
Observed Generation: 1
Reason: SuccessfullyRestatedPetSet
Status: True
Type: RestartPetSet
Last Transition Time: 2022-09-16T11:30:47Z
Message: Vertical scale successful for PostgresOpsRequest: demo/pgops-ha-postgres-6xc1kc
Observed Generation: 1
Reason: SuccessfullyPerformedVerticalScaling
Status: True
Type: VerticalScaling
Last Transition Time: 2022-09-16T11:30:47Z
Message: Controller has successfully scaled the Postgres demo/pgops-ha-postgres-6xc1kc
Observed Generation: 1
Reason: OpsRequestProcessedSuccessfully
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 8m48s KubeDB Enterprise Operator Start processing for PostgresOpsRequest: demo/pgops-ha-postgres-6xc1kc
Normal Starting 8m48s KubeDB Enterprise Operator Pausing Postgres databse: demo/ha-postgres
Normal Successful 8m48s KubeDB Enterprise Operator Successfully paused Postgres database: demo/ha-postgres for PostgresOpsRequest: pgops-ha-postgres-6xc1kc
Normal Starting 8m43s KubeDB Enterprise Operator Restarting Pod: demo/ha-postgres-0
Normal Starting 7m33s KubeDB Enterprise Operator Restarting Pod: demo/ha-postgres-1
Normal Starting 6m23s KubeDB Enterprise Operator Restarting Pod: demo/ha-postgres-2
Normal Successful 5m13s KubeDB Enterprise Operator Successfully restarted Postgres pods for PostgresOpsRequest: demo/pgops-ha-postgres-6xc1kc
Normal Successful 5m8s KubeDB Enterprise Operator Vertical scale successful for PostgresOpsRequest: demo/pgops-ha-postgres-6xc1kc
Normal Starting 5m8s KubeDB Enterprise Operator Resuming Postgres database: demo/ha-postgres
Normal Successful 5m8s KubeDB Enterprise Operator Successfully resumed Postgres database: demo/ha-postgres
Normal Successful 5m8s KubeDB Enterprise Operator Controller has Successfully scaled the Postgres database: demo/ha-postgres
Now, we are going to verify from the Pod, and the Postgres yaml whether the resources of the cluster database has updated to meet up the desired state, Let’s check,
$ kubectl get pod -n demo ha-postgres-0 -o json | jq '.spec.containers[].resources'
{
"limits": {
"cpu": "250m",
"memory": "1Gi"
},
"requests": {
"cpu": "250m",
"memory": "1Gi"
}
}
$ kubectl get postgres -n demo ha-postgres -o json | jq '.spec.podTemplate.spec.resources'
{
"limits": {
"cpu": "250m",
"memory": "1Gi"
},
"requests": {
"cpu": "250m",
"memory": "1Gi"
}
}
The above output verifies that we have successfully autoscaled the resources of the Postgres cluster database.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete postgres -n demo ha-postgres
kubectl delete postgresautoscaler -n demo pg-as-compute
kubectl delete ns demo