How to vertically scale

This guide explains how to adjust the CPU and memory resources of your MySQL instance on Hikube, either via a predetermined preset or by defining explicit values.

Prerequisites

• kubectl configured with your Hikube kubeconfig
• A MySQL instance deployed on your tenant
• Knowledge of your workload's resource requirements

Steps

1. Check current resources

Review the current configuration of your MySQL instance:

kubectl get mariadb example -o yaml | grep -A 5 -E "resources:|resourcesPreset"

Expected output (with preset):

  resourcesPreset: nano

Expected output (with explicit resources):

  resources:
    cpu: 1000m
    memory: 1Gi

2. Choose the scaling method

Hikube offers two approaches for defining resources:

Option A: Use a resourcesPreset

Presets offer predefined resource profiles suited to different use cases:

Preset	CPU	Memory	Use case
nano	250m	128Mi	Tests, minimal development
micro	500m	256Mi	Development, small applications
small	1	512Mi	Lightweight applications
medium	1	1Gi	Standard applications
large	2	2Gi	Moderate workloads
xlarge	4	4Gi	Standard production
2xlarge	8	8Gi	Intensive production

Option B: Define explicit resources

For precise control, define resources.cpu and resources.memory values directly.

warning

If the resources field is defined (explicit CPU and memory), the resourcesPreset value is ignored. The two approaches are mutually exclusive.

3. Option A: Modify the resourcesPreset

To switch from one preset to another, use kubectl patch:

kubectl patch mariadb example --type='merge' -p='
spec:
  resourcesPreset: medium
'

Or modify the manifest directly:

mysql-scaled.yaml

apiVersion: apps.cozystack.io/v1alpha1
kind: MariaDB
metadata:
  name: example
spec:
  replicas: 3
  size: 10Gi
  resourcesPreset: medium

kubectl apply -f mysql-scaled.yaml

4. Option B: Define explicit resources

For fine-grained resource control, specify CPU and memory values directly:

kubectl patch mariadb example --type='merge' -p='
spec:
  resources:
    cpu: 2000m
    memory: 4Gi
'

Or via the full manifest:

mysql-custom-resources.yaml

apiVersion: apps.cozystack.io/v1alpha1
kind: MariaDB
metadata:
  name: example
spec:
  replicas: 3
  size: 10Gi
  resources:
    cpu: 2000m
    memory: 4Gi

kubectl apply -f mysql-custom-resources.yaml

tip

To switch back to a preset after using explicit resources, remove the resources field and set resourcesPreset in your manifest.

Verification

Follow the rolling update of MySQL pods:

kubectl get pods -w | grep mysql-example

Expected output:

mysql-example-0   1/1     Running   0   5m
mysql-example-1   1/1     Running   0   3m
mysql-example-2   1/1     Running   0   1m

Verify that the new resources are properly applied:

kubectl get mariadb example -o yaml | grep -A 5 -E "resources:|resourcesPreset"

note

Vertical scaling triggers a rolling update of the pods. Replicas are restarted one by one to minimize the impact on availability. During this process, the cluster remains accessible for reads via already updated replicas.

Going further

• API Reference: complete list of presets and resource parameters