Chart values and customization in Kubernetes - Commands & Configuration

Introduction

When you install software on Kubernetes using Helm charts, you often want to change how it works. Chart values let you customize settings easily without changing the main files. This helps you adjust the app to your needs.

When you want to change the number of app replicas to handle more users.

When you need to set a custom image version for your app.

When you want to enable or disable features like logging or monitoring.

When you want to add environment variables to your app containers.

When you want to change resource limits like CPU or memory for your app.

Config File - values.yaml

values.yaml

replicaCount: 3
image:
  repository: nginx
  tag: stable
  pullPolicy: IfNotPresent
service:
  type: ClusterIP
  port: 80
resources:
  limits:
    cpu: 500m
    memory: 256Mi
  requests:
    cpu: 250m
    memory: 128Mi

This values.yaml file sets the number of replicas to 3, uses the stable nginx image, and defines resource limits and requests for CPU and memory. It also sets the service type and port. You can change these values to customize your app deployment without editing the main chart files.

Commands

This command installs the nginx chart using the custom settings from the values.yaml file. It applies your changes like replica count and resource limits.

Terminal

helm install my-nginx nginx -f values.yaml

Expected Output

NAME: my-nginx

LAST DEPLOYED: Fri Apr 26 12:00:00 2024

NAMESPACE: default

STATUS: deployed

REVISION: 1

TEST SUITE: None

→

-f - Specifies the custom values file to override default chart settings

This command lists the pods running in your Kubernetes cluster to verify that your app pods are created with the custom settings.

Terminal

kubectl get pods

Expected Output

NAME                           READY   STATUS    RESTARTS   AGE

my-nginx-5d8f9d7f7b-abcde     1/1     Running   0          1m

my-nginx-5d8f9d7f7b-fghij     1/1     Running   0          1m

my-nginx-5d8f9d7f7b-klmno     1/1     Running   0          1m

This command updates the existing nginx release with any changes made in the values.yaml file, allowing you to customize the app after installation.

Terminal

helm upgrade my-nginx nginx -f values.yaml

Expected Output

Release "my-nginx" has been upgraded. Happy Helming!

NAME: my-nginx

LAST DEPLOYED: Fri Apr 26 12:05:00 2024

NAMESPACE: default

STATUS: deployed

REVISION: 2

TEST SUITE: None

→

-f - Uses the custom values file for the upgrade

This command shows the current values used by the installed nginx release, so you can check what customizations are active.

Terminal

helm get values my-nginx

Expected Output

replicaCount: 3

image:

  repository: nginx

  tag: stable

  pullPolicy: IfNotPresent

service:

  type: ClusterIP

  port: 80

resources:

  limits:

    cpu: 500m

    memory: 256Mi

  requests:

    cpu: 250m

    memory: 128Mi

Key Concept

If you remember nothing else from this pattern, remember: customizing Helm chart values lets you change app settings easily without touching the main chart files.

Common Mistakes

Editing the chart's default values.yaml file directly inside the chart folder.

This can cause problems when upgrading the chart because your changes may be overwritten.

Always create and use a separate custom values.yaml file and pass it with the -f flag during install or upgrade.

Not specifying the -f flag when installing or upgrading, so the default values are used.

Your custom settings will be ignored and the app will run with default configurations.

Always include -f values.yaml to apply your custom settings.

Changing values that do not exist or are misspelled in the custom values file.

Helm will ignore unknown keys, so your changes won't take effect and can cause confusion.

Check the chart documentation for valid keys and use correct spelling and indentation.

Summary

Create a custom values.yaml file to set your app's configuration like replicas, image, and resources.

Use helm install or helm upgrade with the -f flag to apply your custom values.

Verify your app pods with kubectl get pods and check active values with helm get values.