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Horizontal Scale Pgpool
This guide will show you how to use KubeDB
Ops-manager operator to scale the replicaset of a Pgpool.
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.Install
KubeDB
Provisioner and Ops-manager operator in your cluster following the steps here.You should be familiar with the following
KubeDB
concepts:
To keep everything isolated, we are going to use 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/pgpool directory of kubedb/docs repository.
Apply Horizontal Scaling on pgpool
Here, we are going to deploy a Pgpool
using a supported version by KubeDB
operator. Then we are going to apply horizontal scaling on it.
Prepare Postgres
Prepare a KubeDB Postgres cluster using this tutorial, or you can use any externally managed postgres but in that case you need to create an appbinding yourself. In this tutorial we will use 3 node Postgres cluster named ha-postgres
.
Prepare Pgpool
Now, we are going to deploy a Pgpool
with version 4.5.0
.
Deploy Pgpool
In this section, we are going to deploy a Pgpool. Then, in the next section we will scale the pgpool using PgpoolOpsRequest
CRD. Below is the YAML of the Pgpool
CR that we are going to create,
apiVersion: kubedb.com/v1alpha2
kind: Pgpool
metadata:
name: pp-horizontal
namespace: demo
spec:
version: "4.5.0"
replicas: 1
postgresRef:
name: ha-postgres
namespace: demo
initConfig:
pgpoolConfig:
max_pool : 60
deletionPolicy: WipeOut
Here we are creating the pgpool with max_pool=60
, it is necessary because we will up scale the pgpool replicas so for that we need larger max_pool
. Let’s create the Pgpool
CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.11.18/docs/examples/pgpool/scaling/pp-horizontal.yaml
pgpool.kubedb.com/pp-horizontal created
Now, wait until pp-horizontal
has status Ready
. i.e,
$ kubectl get pp -n demo
NAME TYPE VERSION STATUS AGE
pp-horizontal kubedb.com/v1alpha2 4.5.0 Ready 2m
Let’s check the number of replicas this pgpool has from the Pgpool object, number of pods the petset have,
$ kubectl get pgpool -n demo pp-horizontal -o json | jq '.spec.replicas'
1
$ kubectl get petset -n demo pp-horizontal -o json | jq '.spec.replicas'
1
We can see from both command that the pgpool has 3 replicas.
We are now ready to apply the PgpoolOpsRequest
CR to scale this pgpool.
Scale Up Replicas
Here, we are going to scale up the replicas of the pgpool to meet the desired number of replicas after scaling.
Create PgpoolOpsRequest
In order to scale up the replicas of the pgpool, we have to create a PgpoolOpsRequest
CR with our desired replicas. Below is the YAML of the PgpoolOpsRequest
CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: PgpoolOpsRequest
metadata:
name: pgpool-horizontal-scale-up
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: pp-horizontal
horizontalScaling:
node: 3
Here,
spec.databaseRef.name
specifies that we are performing horizontal scaling operation onpp-horizontal
pgpool.spec.type
specifies that we are performingHorizontalScaling
on our pgpool.spec.horizontalScaling.replicas
specifies the desired replicas after scaling.
Let’s create the PgpoolOpsRequest
CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.11.18/docs/examples/pgpool/scaling/horizontal-scaling/ppops-hscale-up-ops.yaml
pgpoolopsrequest.ops.kubedb.com/pgpool-horizontal-scale-up created
Verify replicas scaled up successfully
If everything goes well, KubeDB
Ops-manager operator will update the replicas of Pgpool
object and related PetSet
.
Let’s wait for PgpoolOpsRequest
to be Successful
. Run the following command to watch PgpoolOpsRequest
CR,
$ watch kubectl get pgpoolopsrequest -n demo
Every 2.0s: kubectl get pgpoolopsrequest -n demo
NAME TYPE STATUS AGE
pgpool-horizontal-scale-up HorizontalScaling Successful 2m49s
We can see from the above output that the PgpoolOpsRequest
has succeeded. If we describe the PgpoolOpsRequest
we will get an overview of the steps that were followed to scale the pgpool.
$ kubectl describe pgpoolopsrequest -n demo pgpool-horizontal-scale-up
Name: pgpool-horizontal-scale-up
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: PgpoolOpsRequest
Metadata:
Creation Timestamp: 2024-07-17T08:35:13Z
Generation: 1
Resource Version: 62002
UID: ce44f7a1-e78d-4248-a691-62fe1efd11f3
Spec:
Apply: IfReady
Database Ref:
Name: pp-horizontal
Horizontal Scaling:
Node: 3
Type: HorizontalScaling
Status:
Conditions:
Last Transition Time: 2024-07-17T08:35:13Z
Message: Pgpool ops-request has started to horizontally scaling the nodes
Observed Generation: 1
Reason: HorizontalScaling
Status: True
Type: HorizontalScaling
Last Transition Time: 2024-07-17T08:35:16Z
Message: Successfully paused database
Observed Generation: 1
Reason: DatabasePauseSucceeded
Status: True
Type: DatabasePauseSucceeded
Last Transition Time: 2024-07-17T08:35:41Z
Message: Successfully Scaled Up Node
Observed Generation: 1
Reason: HorizontalScaleUp
Status: True
Type: HorizontalScaleUp
Last Transition Time: 2024-07-17T08:35:21Z
Message: patch petset; ConditionStatus:True; PodName:pp-horizontal-1
Observed Generation: 1
Status: True
Type: PatchPetset--pp-horizontal-1
Last Transition Time: 2024-07-17T08:35:26Z
Message: is pod ready; ConditionStatus:True; PodName:pp-horizontal-1
Observed Generation: 1
Status: True
Type: IsPodReady--pp-horizontal-1
Last Transition Time: 2024-07-17T08:35:26Z
Message: client failure; ConditionStatus:True; PodName:pp-horizontal-1
Observed Generation: 1
Status: True
Type: ClientFailure--pp-horizontal-1
Last Transition Time: 2024-07-17T08:35:26Z
Message: is node healthy; ConditionStatus:True; PodName:pp-horizontal-1
Observed Generation: 1
Status: True
Type: IsNodeHealthy--pp-horizontal-1
Last Transition Time: 2024-07-17T08:35:31Z
Message: patch petset; ConditionStatus:True; PodName:pp-horizontal-2
Observed Generation: 1
Status: True
Type: PatchPetset--pp-horizontal-2
Last Transition Time: 2024-07-17T08:35:31Z
Message: pp-horizontal already has desired replicas
Observed Generation: 1
Reason: HorizontalScale
Status: True
Type: HorizontalScale
Last Transition Time: 2024-07-17T08:35:36Z
Message: is pod ready; ConditionStatus:True; PodName:pp-horizontal-2
Observed Generation: 1
Status: True
Type: IsPodReady--pp-horizontal-2
Last Transition Time: 2024-07-17T08:35:36Z
Message: client failure; ConditionStatus:True; PodName:pp-horizontal-2
Observed Generation: 1
Status: True
Type: ClientFailure--pp-horizontal-2
Last Transition Time: 2024-07-17T08:35:36Z
Message: is node healthy; ConditionStatus:True; PodName:pp-horizontal-2
Observed Generation: 1
Status: True
Type: IsNodeHealthy--pp-horizontal-2
Last Transition Time: 2024-07-17T08:35:41Z
Message: Successfully updated Pgpool
Observed Generation: 1
Reason: UpdateDatabase
Status: True
Type: UpdateDatabase
Last Transition Time: 2024-07-17T08:35:41Z
Message: Successfully completed horizontally scale pgpool cluster
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 4m5s KubeDB Ops-manager Operator Start processing for PgpoolOpsRequest: demo/pgpool-horizontal-scale-up
Normal Starting 4m5s KubeDB Ops-manager Operator Pausing Pgpool databse: demo/pp-horizontal
Normal Successful 4m5s KubeDB Ops-manager Operator Successfully paused Pgpool database: demo/pp-horizontal for PgpoolOpsRequest: pgpool-horizontal-scale-up
Normal patch petset; ConditionStatus:True; PodName:pp-horizontal-1 3m57s KubeDB Ops-manager Operator patch petset; ConditionStatus:True; PodName:pp-horizontal-1
Normal is pod ready; ConditionStatus:True; PodName:pp-horizontal-1 3m52s KubeDB Ops-manager Operator is pod ready; ConditionStatus:True; PodName:pp-horizontal-1
Normal is node healthy; ConditionStatus:True; PodName:pp-horizontal-1 3m52s KubeDB Ops-manager Operator is node healthy; ConditionStatus:True; PodName:pp-horizontal-1
Normal patch petset; ConditionStatus:True; PodName:pp-horizontal-2 3m47s KubeDB Ops-manager Operator patch petset; ConditionStatus:True; PodName:pp-horizontal-2
Normal is pod ready; ConditionStatus:True; PodName:pp-horizontal-2 3m42s KubeDB Ops-manager Operator is pod ready; ConditionStatus:True; PodName:pp-horizontal-2
Normal is node healthy; ConditionStatus:True; PodName:pp-horizontal-2 3m42s KubeDB Ops-manager Operator is node healthy; ConditionStatus:True; PodName:pp-horizontal-2
Normal HorizontalScaleUp 3m37s KubeDB Ops-manager Operator Successfully Scaled Up Node
Normal UpdateDatabase 3m37s KubeDB Ops-manager Operator Successfully updated Pgpool
Normal Starting 3m37s KubeDB Ops-manager Operator Resuming Pgpool database: demo/pp-horizontal
Normal Successful 3m37s KubeDB Ops-manager Operator Successfully resumed Pgpool database: demo/pp-horizontal for PgpoolOpsRequest: pgpool-horizontal-scale-up
Now, we are going to verify the number of replicas this pgpool has from the Pgpool object, number of pods the petset have,
$ kubectl get pp -n demo pp-horizontal -o json | jq '.spec.replicas'
3
$ kubectl get petset -n demo pp-horizontal -o json | jq '.spec.replicas'
3
From all the above outputs we can see that the replicas of the pgpool is 3
. That means we have successfully scaled up the replicas of the Pgpool.
Scale Down Replicas
Here, we are going to scale down the replicas of the pgpool to meet the desired number of replicas after scaling.
Create PgpoolOpsRequest
In order to scale down the replicas of the pgpool, we have to create a PgpoolOpsRequest
CR with our desired replicas. Below is the YAML of the PgpoolOpsRequest
CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: PgpoolOpsRequest
metadata:
name: pgpool-horizontal-scale-down
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: pp-horizontal
horizontalScaling:
node: 2
Here,
spec.databaseRef.name
specifies that we are performing horizontal scaling down operation onpp-horizontal
pgpool.spec.type
specifies that we are performingHorizontalScaling
on our pgpool.spec.horizontalScaling.replicas
specifies the desired replicas after scaling.
Let’s create the PgpoolOpsRequest
CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.11.18/docs/examples/pgpool/scaling/horizontal-scaling/ppops-hscale-down-ops.yaml
pgpoolopsrequest.ops.kubedb.com/pgpool-horizontal-scale-down created
Verify replicas scaled down successfully
If everything goes well, KubeDB
Ops-manager operator will update the replicas of Pgpool
object and related PetSet
.
Let’s wait for PgpoolOpsRequest
to be Successful
. Run the following command to watch PgpoolOpsRequest
CR,
$ watch kubectl get pgpoolopsrequest -n demo
Every 2.0s: kubectl get pgpoolopsrequest -n demo
NAME TYPE STATUS AGE
pgpool-horizontal-scale-down HorizontalScaling Successful 75s
We can see from the above output that the PgpoolOpsRequest
has succeeded. If we describe the PgpoolOpsRequest
we will get an overview of the steps that were followed to scale the pgpool.
$ kubectl describe pgpoolopsrequest -n demo pgpool-horizontal-scale-down
Name: pgpool-horizontal-scale-down
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: PgpoolOpsRequest
Metadata:
Creation Timestamp: 2024-07-17T08:52:28Z
Generation: 1
Resource Version: 63600
UID: 019f9d8f-c2b0-4154-b3d3-b715b8805fd7
Spec:
Apply: IfReady
Database Ref:
Name: pp-horizontal
Horizontal Scaling:
Node: 2
Type: HorizontalScaling
Status:
Conditions:
Last Transition Time: 2024-07-17T08:52:28Z
Message: Pgpool ops-request has started to horizontally scaling the nodes
Observed Generation: 1
Reason: HorizontalScaling
Status: True
Type: HorizontalScaling
Last Transition Time: 2024-07-17T08:52:31Z
Message: Successfully paused database
Observed Generation: 1
Reason: DatabasePauseSucceeded
Status: True
Type: DatabasePauseSucceeded
Last Transition Time: 2024-07-17T08:53:16Z
Message: Successfully Scaled Down Node
Observed Generation: 1
Reason: HorizontalScaleDown
Status: True
Type: HorizontalScaleDown
Last Transition Time: 2024-07-17T08:52:36Z
Message: patch petset; ConditionStatus:True; PodName:pp-horizontal-2
Observed Generation: 1
Status: True
Type: PatchPetset--pp-horizontal-2
Last Transition Time: 2024-07-17T08:52:36Z
Message: pp-horizontal already has desired replicas
Observed Generation: 1
Reason: HorizontalScale
Status: True
Type: HorizontalScale
Last Transition Time: 2024-07-17T08:52:41Z
Message: get pod; ConditionStatus:False
Observed Generation: 1
Status: False
Type: GetPod
Last Transition Time: 2024-07-17T08:53:11Z
Message: get pod; ConditionStatus:True; PodName:pp-horizontal-2
Observed Generation: 1
Status: True
Type: GetPod--pp-horizontal-2
Last Transition Time: 2024-07-17T08:53:16Z
Message: Successfully updated Pgpool
Observed Generation: 1
Reason: UpdateDatabase
Status: True
Type: UpdateDatabase
Last Transition Time: 2024-07-17T08:53:16Z
Message: Successfully completed horizontally scale pgpool cluster
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 96s KubeDB Ops-manager Operator Start processing for PgpoolOpsRequest: demo/pgpool-horizontal-scale-down
Normal Starting 96s KubeDB Ops-manager Operator Pausing Pgpool databse: demo/pp-horizontal
Normal Successful 96s KubeDB Ops-manager Operator Successfully paused Pgpool database: demo/pp-horizontal for PgpoolOpsRequest: pgpool-horizontal-scale-down
Normal patch petset; ConditionStatus:True; PodName:pp-horizontal-2 88s KubeDB Ops-manager Operator patch petset; ConditionStatus:True; PodName:pp-horizontal-2
Normal get pod; ConditionStatus:False 83s KubeDB Ops-manager Operator get pod; ConditionStatus:False
Normal get pod; ConditionStatus:True; PodName:pp-horizontal-2 53s KubeDB Ops-manager Operator get pod; ConditionStatus:True; PodName:pp-horizontal-2
Normal HorizontalScaleDown 48s KubeDB Ops-manager Operator Successfully Scaled Down Node
Normal UpdateDatabase 48s KubeDB Ops-manager Operator Successfully updated Pgpool
Normal Starting 48s KubeDB Ops-manager Operator Resuming Pgpool database: demo/pp-horizontal
Normal Successful 48s KubeDB Ops-manager Operator Successfully resumed Pgpool database: demo/pp-horizontal for PgpoolOpsRequest: pgpool-horizontal-scale-down
Now, we are going to verify the number of replicas this pgpool has from the Pgpool object, number of pods the petset have,
$ kubectl get pp -n demo pp-horizontal -o json | jq '.spec.replicas'
2
$ kubectl get petset -n demo pp-horizontal -o json | jq '.spec.replicas'
2
From all the above outputs we can see that the replicas of the pgpool is 2
. That means we have successfully scaled up the replicas of the Pgpool.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete mg -n pp-horizontal
kubectl delete pgpoolopsrequest -n demo pgpool-horizontal-scale-down