Creating custom Helm charts in Kubernetes - Quick Revision & Summary

Recall & Review

beginner

What is a Helm chart?

A Helm chart is a package that contains all the files needed to create a Kubernetes application. It includes templates, configuration files, and metadata.

beginner

What is the purpose of the 'values.yaml' file in a Helm chart?

The 'values.yaml' file holds default configuration values that can be customized when installing the chart. It helps users set parameters without changing templates.

beginner

Which command initializes a new Helm chart named 'myapp'?

The command is: helm create myapp

intermediate

How do Helm templates help in Kubernetes deployments?

Helm templates allow you to write reusable Kubernetes manifests with placeholders. These placeholders get replaced with actual values during deployment, making customization easy.

beginner

What file in a Helm chart contains metadata like chart name, version, and description?

The 'Chart.yaml' file contains metadata such as the chart's name, version, description, and dependencies.

Which Helm command packages a chart into a versioned archive?

A helm upgrade

B helm install

C helm create

D helm package

The 'helm package' command bundles a chart directory into a versioned .tgz archive.

Where do you define default configuration values for a Helm chart?

A templates/deployment.yaml

B values.yaml

C Chart.yaml

D README.md

The 'values.yaml' file holds default values that templates use during rendering.

What does the 'helm install' command do?

A Deploys a Helm chart to Kubernetes

B Creates a new Helm chart

C Deletes a Helm release

D Packages a Helm chart

'helm install' deploys the chart to the Kubernetes cluster as a release.

Which file contains the Kubernetes resource templates in a Helm chart?

A values.yaml

B Chart.yaml

C templates/

D LICENSE

The 'templates/' directory holds Kubernetes manifest templates.

How can you customize a Helm chart during installation?

A By passing custom values with --set or a values file

B By editing Chart.yaml

C By changing the helm binary

D By deleting templates

You customize charts by passing values with --set or using a custom values file.

Explain the main components of a custom Helm chart and their roles.

Think about what files you find inside a Helm chart folder and what each does.

Describe the steps to create and deploy a simple custom Helm chart.

Start from creating the chart, then customizing, then deploying.

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