Creating custom Helm charts in Kubernetes - Visual Walkthrough

Process Flow - Creating custom Helm charts

Start: Define Chart Structure

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Create Chart.yaml

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Create values.yaml

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Create templates/ directory

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Add Kubernetes YAML templates

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Use placeholders for values

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Package and install chart

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Chart deployed with custom values

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END

This flow shows the step-by-step process of creating a Helm chart: starting with structure, adding metadata, templates, and values, then packaging and deploying.

Execution Sample

Kubernetes

helm create mychart
# Edit mychart/Chart.yaml
# Edit mychart/values.yaml
# Add templates/deployment.yaml with placeholders
helm install myrelease mychart -f custom-values.yaml

This sequence creates a Helm chart, customizes it, and installs it with custom values.

Process Table

Step	Action	File/Command	Effect/Result
1	Create new chart skeleton	helm create mychart	Folder 'mychart' with default files created
2	Edit Chart.yaml	mychart/Chart.yaml	Set chart name, version, description
3	Edit values.yaml	mychart/values.yaml	Define default configuration values
4	Add template with placeholders	mychart/templates/deployment.yaml	Template uses {{ .Values.key }} for dynamic values
5	Package chart (optional)	helm package mychart	Chart packaged as .tgz file
6	Install chart with custom values	helm install myrelease mychart -f custom-values.yaml	Kubernetes resources deployed with custom settings
7	Verify deployment	kubectl get pods	Pods running as per chart configuration
8	Exit	-	Chart deployed successfully, process complete

💡 Chart installed and Kubernetes resources created, no further steps

Status Tracker

Variable/File	Start	After Step 2	After Step 3	After Step 4	After Step 6	Final
Chart.yaml	empty template	name, version set	unchanged	unchanged	unchanged	unchanged
values.yaml	default values	unchanged	custom values added	unchanged	used for deployment	unchanged
templates/deployment.yaml	default template	unchanged	unchanged	placeholders added	rendered with values	unchanged
Kubernetes deployment	none	none	none	none	created with custom values	running pods

Key Moments - 3 Insights

Why do we use placeholders like {{ .Values.key }} in templates?

Placeholders allow templates to use dynamic values from values.yaml or custom files, as shown in step 4 and step 6 of the execution_table.

What happens if we don't provide a custom values file during install?

Helm uses default values from values.yaml, so deployment uses those defaults (see step 6 and variable_tracker for values.yaml).

Why do we need to edit Chart.yaml if it has defaults?

Chart.yaml defines metadata like name and version, important for identifying the chart, as shown in step 2.

Visual Quiz - 3 Questions

Look at the execution_table, at which step are placeholders added to templates?

A Step 2

B Step 4

C Step 6

D Step 1

💡 Hint

Check the 'Action' column for 'Add template with placeholders' in execution_table

According to variable_tracker, what is the state of values.yaml after Step 3?

A Custom values added

B Default values only

C Empty file

D Used for deployment

💡 Hint

Look at values.yaml row under 'After Step 3' in variable_tracker

If you skip editing Chart.yaml, what is the likely effect?

A Chart will fail to install

B Templates won't render

C Chart installs with default metadata

D Values.yaml is ignored

💡 Hint

Refer to step 2 and the key_moments about Chart.yaml importance

Concept Snapshot

Creating custom Helm charts:
1. Use 'helm create <name>' to scaffold.
2. Edit Chart.yaml for metadata.
3. Define default config in values.yaml.
4. Add templates with {{ .Values.key }} placeholders.
5. Install with 'helm install' and optional custom values.
6. Kubernetes resources deploy using these configs.

Full Transcript

Creating custom Helm charts involves starting with a scaffold using 'helm create'. Then, you edit Chart.yaml to set the chart's name and version. Next, you define default configuration values in values.yaml. Templates in the templates directory use placeholders like {{ .Values.key }} to insert these values dynamically. You can package the chart or install it directly with 'helm install', optionally providing a custom values file to override defaults. This process results in Kubernetes resources deployed with your custom settings.

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