Creating custom Helm charts in Kubernetes - Try It Yourself

Creating custom Helm charts

📖 Scenario: You are working as a DevOps engineer for a small company. You need to package a simple web application into a Helm chart so it can be easily deployed and managed on Kubernetes clusters.

🎯 Goal: Build a custom Helm chart for a basic web application with configurable image and replica count.

📋 What You'll Learn

Create the Helm chart directory structure with Chart.yaml and values.yaml

Add a configuration variable for the number of replicas

Write the deployment template using Helm template syntax

Output the rendered Kubernetes deployment manifest

💡 Why This Matters

🌍 Real World

Helm charts help package and deploy applications on Kubernetes clusters easily and consistently.

💼 Career

Knowing how to create custom Helm charts is a key skill for DevOps engineers managing Kubernetes deployments.

1

Create Helm chart metadata

Create a file named Chart.yaml with the following content exactly:
apiVersion: v2
name: simple-webapp
version: 0.1.0

Kubernetes

# Create Chart.yaml file with apiVersion, name, and version
# Your code here

Hint

The Chart.yaml file defines the chart's metadata. Use exact keys and values as shown.

2

Add default values configuration

Create a file named values.yaml with these exact entries:
replicaCount: 2
image:
repository: nginx
tag: stable

Kubernetes

apiVersion: v2
name: simple-webapp
version: 0.1.0

# Create values.yaml with replicaCount and image repository and tag
# Your code here

Hint

The values.yaml file holds default settings for your chart. Indentation matters in YAML.

3

Write deployment template using Helm syntax

Create a file named templates/deployment.yaml with a Kubernetes Deployment manifest that uses Helm template syntax to:
- Set replicas to {{ .Values.replicaCount }}
- Set container image to {{ .Values.image.repository }}:{{ .Values.image.tag }}
- Name the deployment {{ .Chart.Name }}

Kubernetes

apiVersion: v2
name: simple-webapp
version: 0.1.0

replicaCount: 2
image:
  repository: nginx
  tag: stable

# Create templates/deployment.yaml with Helm template syntax
# Your code here

Hint

Use double curly braces {{ }} to insert values from values.yaml and chart metadata.

4

Render and output the Helm template

Run the Helm template command to render the deployment manifest and print the output exactly:
helm template simple-webapp .

Kubernetes

apiVersion: v2
name: simple-webapp
version: 0.1.0

replicaCount: 2
image:
  repository: nginx
  tag: stable

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Chart.Name }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Chart.Name }}
  template:
    metadata:
      labels:
        app: {{ .Chart.Name }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          ports:
            - containerPort: 80

# Run the command 'helm template simple-webapp .' in your terminal to see the rendered output
# Your code here

Hint

Use the helm template command in your terminal inside the chart directory to see the rendered Kubernetes manifest.

Practice

1. What is the primary purpose of a Helm chart in Kubernetes?

easy

A. To package and deploy Kubernetes applications easily

B. To monitor Kubernetes cluster health

C. To replace kubectl commands

D. To create virtual machines in Kubernetes

Solution

1. Step 1: Understand Helm chart role

   A Helm chart bundles Kubernetes resources and configurations for an app.

2. Step 2: Identify main use

   It simplifies sharing and deploying apps by packaging them.

3. Final Answer:

   To package and deploy Kubernetes applications easily -> Option A

4. Quick Check:

   Helm charts = package & deploy apps [OK]

Hint: Helm charts bundle apps for easy deployment [OK]

Common Mistakes:

• Confusing Helm with monitoring tools
• Thinking Helm replaces kubectl commands
• Assuming Helm creates virtual machines

2. Which command initializes a new Helm chart with default files?

easy

A. helm init

B. helm start

C. helm create

D. helm new

Solution

1. Step 1: Recall Helm commands

   The command to create a new chart with default files is helm create.

2. Step 2: Eliminate incorrect options

   helm init is deprecated, helm start and helm new do not exist.

3. Final Answer:

   helm create -> Option C

4. Quick Check:

   New chart command = helm create [OK]

Hint: Use 'helm create' to start a new chart fast [OK]

Common Mistakes:

• Using 'helm init' which is deprecated
• Trying 'helm start' or 'helm new' which are invalid
• Confusing 'helm create' with 'helm install'

3. Given this snippet in a Helm template file:

{{ .Values.replicaCount }}

If values.yaml sets replicaCount: 3, what will this render in the deployed manifest?

medium

A. {{ .Values.replicaCount }}

B. 3

C. replicaCount

D. null

Solution

1. Step 1: Understand Helm template variables

   {{ .Values.replicaCount }} inserts the value of replicaCount from values.yaml.

2. Step 2: Check the value in values.yaml

   Since replicaCount is set to 3, the template renders the number 3.

3. Final Answer:

   3 -> Option B

4. Quick Check:

   Template variable renders value = 3 [OK]

Hint: Template {{ .Values.key }} outputs the key's value [OK]

Common Mistakes:

• Thinking the template syntax prints literally
• Confusing key name with value
• Assuming missing values render as null

4. You created a Helm chart but get an error: template: deployment.yaml:10: unexpected EOF. What is the most likely cause?

medium

A. Cluster is not reachable

B. Incorrect image name in values.yaml

C. Helm version is outdated

D. Missing closing bracket in template syntax

Solution

1. Step 1: Analyze error message

   "unexpected EOF" means the template ended unexpectedly, often due to missing closing brackets.

2. Step 2: Identify common template syntax errors

   Missing a closing }} or {% causes this error.

3. Final Answer:

   Missing closing bracket in template syntax -> Option D

4. Quick Check:

   Unexpected EOF = missing closing bracket [OK]

Hint: Check all {{ }} pairs are closed properly [OK]

Common Mistakes:

• Blaming image name for syntax errors
• Assuming cluster issues cause template parse errors
• Ignoring template syntax mistakes

5. You want to create a Helm chart that allows users to set a custom container port via values.yaml. Which snippet correctly uses this value in the deployment.yaml template?

hard

A. ports:
- containerPort: {{ .Values.containerPort }}

B. ports:
- containerPort: $containerPort

C. ports:
- containerPort: {{ containerPort }}

D. ports:
- containerPort: .Values.containerPort

Solution

1. Step 1: Recall Helm template syntax for values

   Use {{ .Values.key }} to insert values from values.yaml.

2. Step 2: Check each option

   ports: - containerPort: {{ .Values.containerPort }} uses correct Helm syntax. The other options use invalid or incomplete syntax.

3. Final Answer:

   ports: - containerPort: {{ .Values.containerPort }} -> Option A

4. Quick Check:

   Use {{ .Values.key }} for values in templates [OK]

Hint: Use {{ .Values.key }} to access values.yaml keys [OK]

Common Mistakes:

• Using shell variable syntax like $containerPort
• Omitting the dot before Values
• Not using handlebars {{ }} for templating