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Autoscaling the Compute Resource of a RabbitMQ

This guide will show you how to use KubeDB to autoscaling compute resources i.e. cpu and memory of a RabbitMQ.

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.
Install KubeDB Provisioner, Ops-manager and Autoscaler operator in your cluster following the steps here.
Install Metrics Server from 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/rabbitmq directory of kubedb/docs repository.

Autoscaling of RabbitMQ

In this section, we are going to deploy a RabbitMQ with version 3.13.2 Then, in the next section we will set up autoscaling for this RabbitMQ using RabbitMQAutoscaler CRD. Below is the YAML of the RabbitMQ CR that we are going to create,

apiVersion: kubedb.com/v1alpha2
kind: RabbitMQ
metadata:
  name: rabbitmq-autoscale
  namespace: demo
spec:
  version: "3.13.2"
  replicas: 1
  storage:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
    storageClassName: standard
  storageType: Durable
  deletionPolicy: WipeOut
  podTemplate:
    spec:
      containers:
        - name: rabbitmq
          resources:
            requests:
              cpu: "0.5m"
              memory: "1Gi"
            limits:
              cpu: "1"
              memory: "2Gi"
  serviceTemplates:
    - alias: primary
      spec:
        type: LoadBalancer

Let’s create the RabbitMQ CRO we have shown above,

$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.8.21/docs/examples/rabbitmq/autoscaling/compute/rabbitmq-autoscale.yaml
rabbitmq.kubedb.com/rabbitmq-autoscale created

Now, wait until rabbitmq-autoscale has status Ready. i.e,

$ kubectl get rm -n demo
NAME                 TYPE                  VERSION   STATUS   AGE
rabbitmq-autoscale   kubedb.com/v1alpha2   3.13.2     Ready    22s

Let’s check the Pod containers resources,

$ kubectl get pod -n demo rabbitmq-autoscale-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "1",
    "memory": "2Gi"
  },
  "requests": {
    "cpu": "0.5m",
    "memory": "1Gi"
  }
}

Let’s check the RabbitMQ resources,

$ kubectl get rabbitmq -n demo rabbitmq-autoscale -o json | jq '.spec.podTemplate.spec.containers[0].resources'
{
  "limits": {
    "cpu": "1",
    "memory": "2Gi"
  },
  "requests": {
    "cpu": "0.5m",
    "memory": "1Gi"
  }
}

You can see from the above outputs that the resources are same as the one we have assigned while deploying the rabbitmq.

We are now ready to apply the RabbitMQAutoscaler CRO to set up autoscaling for this database.

Compute Resource Autoscaling

Here, we are going to set up compute (cpu and memory) autoscaling using a RabbitMQAutoscaler Object.

Create RabbitMQAutoscaler Object

In order to set up compute resource autoscaling for this RabbitMQ, we have to create a RabbitMQAutoscaler CRO with our desired configuration. Below is the YAML of the RabbitMQAutoscaler object that we are going to create,

apiVersion: autoscaling.kubedb.com/v1alpha1
kind: RabbitMQAutoscaler
metadata:
  name: rabbitmq-autoscale-ops
  namespace: demo
spec:
  databaseRef:
    name: rabbitmq-autoscale
  compute:
    rabbitmq:
      trigger: "On"
      podLifeTimeThreshold: 5m
      resourceDiffPercentage: 20
      minAllowed:
        cpu: 600m
        memory: 1.2Gi
      maxAllowed:
        cpu: 1
        memory: 2Gi
      controlledResources: ["cpu", "memory"]
      containerControlledValues: "RequestsAndLimits"

Here,

spec.databaseRef.name specifies that we are performing compute resource autoscaling on rabbitmq-autoscale.
spec.compute.rabbitmq.trigger specifies that compute resource autoscaling is enabled for this rabbitmq.
spec.compute.rabbitmq.podLifeTimeThreshold specifies the minimum lifetime for at least one of the pod to initiate a vertical scaling.
spec.compute.rabbitmq.resourceDiffPercentage specifies 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.rabbitmq.minAllowed specifies the minimum allowed resources for this rabbitmq.
spec.compute.rabbitmq.maxAllowed specifies the maximum allowed resources for this rabbitmq.
spec.compute.rabbitmq.controlledResources specifies the resources that are controlled by the autoscaler.
spec.compute.rabbitmq.containerControlledValues specifies which resource values should be controlled. The default is “RequestsAndLimits”.
spec.opsRequestOptions contains the options to pass to the created OpsRequest. It has 2 fields. Know more about them here : timeout, apply.

Let’s create the RabbitMQAutoscaler CR we have shown above,

$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.8.21/docs/examples/rabbitmq/autoscaling/compute/rabbitmq-autoscaler.yaml
rabbitmqautoscaler.autoscaling.kubedb.com/rabbitmq-autoscaler-ops created

Verify Autoscaling is set up successfully

Let’s check that the rabbitmqautoscaler resource is created successfully,

$ kubectl get rabbitmqautoscaler -n demo
NAME                   AGE
rabbitmq-autoscale-ops   6m55s

$ kubectl describe rabbitmqautoscaler rabbitmq-autoscale-ops -n demo
Name:         rabbitmq-autoscale-ops
Namespace:    demo
Labels:       <none>
Annotations:  <none>
API Version:  autoscaling.kubedb.com/v1alpha1
Kind:         RabbitMQAutoscaler
Metadata:
  Creation Timestamp:  2024-07-17T12:09:17Z
  Generation:          1
  Resource Version:    81569
  UID:                 3841c30b-3b19-4740-82f5-bf8e257ddc18
Spec:
  Compute:
    rabbitmq:
      Container Controlled Values:  RequestsAndLimits
      Controlled Resources:
        cpu
        memory
      Max Allowed:
        Cpu:     1
        Memory:  1Gi
      Min Allowed:
        Cpu:                     600m
        Memory:                  1.2Gi
      Pod Life Time Threshold:   5m0s
      Resource Diff Percentage:  20
      Trigger:                   On
  Database Ref:
    Name:  rabbitmq-autoscale
  Ops Request Options:
    Apply:  IfReady
Status:
  Checkpoints:
    Cpu Histogram:
      Bucket Weights:
        Index:              0
        Weight:             10000
      Reference Timestamp:  2024-07-17T12:10:00Z
      Total Weight:         0.8733542386168607
    First Sample Start:     2024-07-17T12:09:14Z
    Last Sample Start:      2024-07-17T12:15:06Z
    Last Update Time:       2024-07-17T12:15:38Z
    Memory Histogram:
      Bucket Weights:
        Index:              11
        Weight:             10000
      Reference Timestamp:  2024-07-17T12:15:00Z
      Total Weight:         0.7827734162991002
    Ref:
      Container Name:     rabbitmq
      Vpa Object Name:    rabbitmq-autoscale
    Total Samples Count:  6
    Version:              v3
  Conditions:
    Last Transition Time:  2024-07-17T12:10:37Z
    Message:               Successfully created RabbitMQOpsRequest demo/rmops-rabbitmq-autoscale-zzell6
    Observed Generation:   1
    Reason:                CreateOpsRequest
    Status:                True
    Type:                  CreateOpsRequest
  Vpas:
    Conditions:
      Last Transition Time:  2024-07-17T12:09:37Z
      Status:                True
      Type:                  RecommendationProvided
    Recommendation:
      Container Recommendations:
        Container Name:  rabbitmq
        Lower Bound:
          Cpu:     600m
          Memory:  1.2Gi
        Target:
          Cpu:     600m
          Memory:  1.2Gi
        Uncapped Target:
          Cpu:     500m
          Memory:  2621445k
        Upper Bound:
          Cpu:     1
          Memory:  2Gi
    Vpa Name:      rabbitmq-autoscale
Events:            <none>

So, the RabbitMQautoscaler resource is created successfully.

you can see in the Status.VPAs.Recommendation section, that recommendation has been generated for our RabbitMQ. Our autoscaler operator continuously watches the recommendation generated and creates an rabbitmqopsrequest based on the recommendations, if the rabbitmq pods are needed to scaled up or down.

Let’s watch the rabbitmqopsrequest in the demo namespace to see if any rabbitmqopsrequest object is created. After some time you’ll see that a rabbitmqopsrequest will be created based on the recommendation.

$ watch kubectl get rabbitmqopsrequest -n demo
Every 2.0s: kubectl get rabbitmqopsrequest -n demo
NAME                            TYPE              STATUS        AGE
rmops-rabbitmq-autoscale-zzell6   VerticalScaling   Progressing   1m48s

Let’s wait for the ops request to become successful.

$ watch kubectl get rabbitmqopsrequest -n demo
Every 2.0s: kubectl get rabbitmqopsrequest -n demo
NAME                            TYPE              STATUS       AGE
rmops-rabbitmq-autoscale-zzell6   VerticalScaling   Successful   3m40s

We can see from the above output that the RabbitMQOpsRequest has succeeded. If we describe the RabbitMQOpsRequest we will get an overview of the steps that were followed to scale the RabbitMQ.

$ kubectl describe rabbitmqopsrequest -n demo rmops-rabbitmq-autoscale-zzell6
Name:         rmops-rabbitmq-autoscale-zzell6
Namespace:    demo
Labels:       app.kubernetes.io/component=connection-pooler
              app.kubernetes.io/instance=rabbitmq-autoscale
              app.kubernetes.io/managed-by=kubedb.com
              app.kubernetes.io/name=rabbitmqs.kubedb.com
Annotations:  <none>
API Version:  ops.kubedb.com/v1alpha1
Kind:         RabbitMQOpsRequest
Metadata:
  Creation Timestamp:  2024-07-17T12:10:37Z
  Generation:          1
  Owner References:
    API Version:           autoscaling.kubedb.com/v1alpha1
    Block Owner Deletion:  true
    Controller:            true
    Kind:                  RabbitMQAutoscaler
    Name:                  rabbitmq-autoscale-ops
    UID:                   3841c30b-3b19-4740-82f5-bf8e257ddc18
  Resource Version:        81200
  UID:                     57f99d31-af3d-4157-aa61-0f509ec89bbd
Spec:
  Apply:  IfReady
  Database Ref:
    Name:  rabbitmq-autoscale
  Type:    VerticalScaling
  Vertical Scaling:
    Node:
      Resources:
        Limits:
          Cpu:     400m
          Memory:  400Mi
        Requests:
          Cpu:     400m
          Memory:  400Mi
Status:
  Conditions:
    Last Transition Time:  2024-07-17T12:10:37Z
    Message:               RabbitMQ ops-request has started to vertically scaling the RabbitMQ nodes
    Observed Generation:   1
    Reason:                VerticalScaling
    Status:                True
    Type:                  VerticalScaling
    Last Transition Time:  2024-07-17T12:10:40Z
    Message:               Successfully paused database
    Observed Generation:   1
    Reason:                DatabasePauseSucceeded
    Status:                True
    Type:                  DatabasePauseSucceeded
    Last Transition Time:  2024-07-17T12:10:40Z
    Message:               Successfully updated PetSets Resources
    Observed Generation:   1
    Reason:                UpdatePetSets
    Status:                True
    Type:                  UpdatePetSets
    Last Transition Time:  2024-07-17T12:11:25Z
    Message:               Successfully Restarted Pods With Resources
    Observed Generation:   1
    Reason:                RestartPods
    Status:                True
    Type:                  RestartPods
    Last Transition Time:  2024-07-17T12:10:45Z
    Message:               get pod; ConditionStatus:True; PodName:rabbitmq-autoscale-0
    Observed Generation:   1
    Status:                True
    Type:                  GetPod--rabbitmq-autoscale-0
    Last Transition Time:  2024-07-17T12:10:45Z
    Message:               evict pod; ConditionStatus:True; PodName:rabbitmq-autoscale-0
    Observed Generation:   1
    Status:                True
    Type:                  EvictPod--rabbitmq-autoscale-0
    Last Transition Time:  2024-07-17T12:11:20Z
    Message:               check pod running; ConditionStatus:True; PodName:rabbitmq-autoscale-0
    Observed Generation:   1
    Status:                True
    Type:                  CheckPodRunning--rabbitmq-autoscale-0
    Last Transition Time:  2024-07-17T12:11:26Z
    Message:               Successfully completed the vertical scaling for rabbitmq
    Observed Generation:   1
    Reason:                Successful
    Status:                True
    Type:                  Successful
  Observed Generation:     1
  Phase:                   Successful
Events:
  Type     Reason                                                                Age    From                         Message
  ----     ------                                                                ----   ----                         -------
  Normal   Starting                                                              8m19s  KubeDB Ops-manager Operator  Start processing for rabbitmqOpsRequest: demo/rmops-rabbitmq-autoscale-zzell6
  Normal   Starting                                                              8m19s  KubeDB Ops-manager Operator  Pausing rabbitmq databse: demo/rabbitmq-autoscale
  Normal   Successful                                                            8m19s  KubeDB Ops-manager Operator  Successfully paused rabbitmq database: demo/rabbitmq-autoscale for rabbitmqOpsRequest: rmops-rabbitmq-autoscale-zzell6
  Normal   UpdatePetSets                                                         8m16s  KubeDB Ops-manager Operator  Successfully updated PetSets Resources
  Warning  get pod; ConditionStatus:True; PodName:rabbitmq-autoscale-0             8m11s  KubeDB Ops-manager Operator  get pod; ConditionStatus:True; PodName:rabbitmq-autoscale-0
  Warning  evict pod; ConditionStatus:True; PodName:rabbitmq-autoscale-0           8m11s  KubeDB Ops-manager Operator  evict pod; ConditionStatus:True; PodName:rabbitmq-autoscale-0
  Warning  check pod running; ConditionStatus:False; PodName:rabbitmq-autoscale-0  8m6s   KubeDB Ops-manager Operator  check pod running; ConditionStatus:False; PodName:rabbitmq-autoscale-0
  Warning  check pod running; ConditionStatus:True; PodName:rabbitmq-autoscale-0   7m36s  KubeDB Ops-manager Operator  check pod running; ConditionStatus:True; PodName:rabbitmq-autoscale-0
  Normal   RestartPods                                                           7m31s  KubeDB Ops-manager Operator  Successfully Restarted Pods With Resources
  Normal   Starting                                                              7m31s  KubeDB Ops-manager Operator  Resuming rabbitmq database: demo/rabbitmq-autoscale
  Normal   Successful                                                            7m30s  KubeDB Ops-manager Operator  Successfully resumed RabbitMQ database: demo/rabbitmq-autoscale for RabbitMQOpsRequest: rmops-rabbitmq-autoscale-zzell6

Now, we are going to verify from the Pod, and the RabbitMQ yaml whether the resources of the RabbitMQ has updated to meet up the desired state, Let’s check,

$ kubectl get pod -n demo rabbitmq-autoscale-0 -o json | jq '.spec.containers[].resources'
{
  "limits": {
    "cpu": "1",
    "memory": "2Gi"
  },
  "requests": {
    "cpu": "600m",
    "memory": "1.2Gi"
  }
}

$ kubectl get rabbitmq -n demo rabbitmq-autoscale -o json | jq '.spec.podTemplate.spec.containers[0].resources'
{
  "limits": {
    "cpu": "1",
    "memory": "2Gi"
  },
  "requests": {
    "cpu": "600m",
    "memory": "1.2Gi"
  }
}

The above output verifies that we have successfully auto-scaled the resources of the rabbitmq.

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

kubectl delete rm -n demo rabbitmq-autoscale
kubectl delete rabbitmqautoscaler -n demo rabbitmq-autoscale-ops

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