Chart templates and values.yaml in Kubernetes - Step-by-Step Execution

Process Flow - Chart templates and values.yaml

Start: Helm Chart

↓

Read values.yaml

↓

Load templates

↓

Substitute values into templates

↓

Generate Kubernetes manifests

↓

Deploy manifests to cluster

Helm reads values.yaml, loads templates, replaces placeholders with values, then creates Kubernetes manifests for deployment.

Execution Sample

Kubernetes

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ .Values.name }}-config
  labels:
    app: {{ .Values.app }}

A Helm template for a ConfigMap using values from values.yaml to fill name and app labels.

Process Table

Step	Action	Template Line	Value Used	Resulting Line
1	Read values.yaml	name: myapp	name=myapp	name: myapp
2	Read values.yaml	app: demo	app=demo	app: demo
3	Load template line	metadata.name: {{ .Values.name }}-config	name=myapp	metadata.name: myapp-config
4	Load template line	labels.app: {{ .Values.app }}	app=demo	labels.app: demo
5	Generate final manifest	Full ConfigMap	Values substituted	ConfigMap with name 'myapp-config' and label 'app: demo'

💡 All placeholders replaced with values from values.yaml, manifest ready for deployment

Status Tracker

Variable	Start	After Step 1	After Step 3	Final
name	undefined	myapp	myapp	myapp
app	undefined	demo	demo	demo

Key Moments - 2 Insights

Why does {{ .Values.name }} get replaced with 'myapp'?

Because in the execution_table at Step 1, values.yaml defines name as 'myapp', which Helm uses to substitute in the template at Step 3.

What happens if a value is missing in values.yaml?

Helm will leave the placeholder empty or use a default if defined; this is shown by no substitution in the execution_table rows for that value.

Visual Quiz - 3 Questions

Look at the execution_table at Step 3, what is the resulting line after substitution?

A metadata.name: config-myapp

B metadata.name: {{ .Values.name }}-config

C metadata.name: myapp-config

D metadata.name: myapp

💡 Hint

Check the 'Resulting Line' column at Step 3 in the execution_table.

At which step does Helm read the values.yaml file?

A Step 1

B Step 3

C Step 5

D Step 4

💡 Hint

Look at the 'Action' column in the execution_table for when values.yaml is read.

If the values.yaml had app: 'testapp' instead of 'demo', what would be the label in the final manifest?

A app: demo

B app: testapp

C app: myapp

D app: config

💡 Hint

Refer to the variable_tracker for 'app' value changes and the substitution in Step 4.

Concept Snapshot

Helm charts use templates with placeholders like {{ .Values.key }}.
Values.yaml provides the actual values.
Helm reads values.yaml, substitutes values into templates.
Generates Kubernetes manifests ready for deployment.
Missing values can cause empty fields or use defaults.
This process simplifies app configuration and deployment.

Full Transcript

This visual execution shows how Helm uses values.yaml and templates to create Kubernetes manifests. First, Helm reads values.yaml to get values like 'name' and 'app'. Then it loads the template file which contains placeholders such as {{ .Values.name }}. Helm replaces these placeholders with the actual values from values.yaml. For example, {{ .Values.name }} becomes 'myapp'. This substitution happens line by line, resulting in a complete manifest file. The final manifest can then be deployed to the Kubernetes cluster. If a value is missing in values.yaml, Helm may leave the placeholder empty or use a default if specified. This process helps manage configuration easily and consistently.