Homework

Complete these tasks before Lesson 03. Focus on customizing charts and understanding the relationship between values, templates, and rendered output.

Task 1: Customize a Chart for a Real Application

Goal: Modify the scaffolded chart to deploy a different application image with custom configuration, demonstrating your understanding of values.yaml and Chart.yaml.

Instructions

Scaffold a new chart:
```
helm create webapp
```
Edit webapp/Chart.yaml:
- Change description to something meaningful (e.g., "A custom web application chart")
- Set appVersion to "latest"
Edit webapp/values.yaml to customize the deployment:
- Change image.repository to httpd (Apache) or another image of your choice
- Set image.tag to "2.4"
- Set replicaCount to 2
- Set service.type to NodePort
- Set service.port to 80
Render the templates locally and verify the output:
```
helm template my-webapp webapp
```

Install the chart, verify the pods are running, then uninstall:

helm install my-webapp webapp
kubectl get pods -l app.kubernetes.io/instance=my-webapp
helm uninstall my-webapp

Self-Check

The rendered Deployment uses your chosen image and tag (not nginx)
The rendered Deployment specifies 2 replicas
The rendered Service is type NodePort
The chart installs successfully and 2 pods reach Running state

Task 2: Write a Custom NOTES.txt

Goal: Replace the default NOTES.txt template with a custom one that displays useful information based on the chart’s configured values.

Instructions

Using the webapp chart from Task 1, open webapp/templates/NOTES.txt.
Replace the contents with a custom template that:
- Displays the release name and namespace
- Shows the image and tag being deployed
- Provides the correct access command based on .Values.service.type (ClusterIP vs. NodePort)
Your NOTES.txt should use at least these template variables:
- {{ .Release.Name }}
- {{ .Release.Namespace }}
- {{ .Values.image.repository }}
- {{ .Values.image.tag }}
- {{ .Values.service.type }}

Test your NOTES.txt output:

# Render locally to preview
helm template my-webapp webapp --show-only templates/NOTES.txt

# Install and verify the notes display correctly
helm install my-webapp webapp
helm status my-webapp

Clean up:
```
helm uninstall my-webapp
```

Self-Check

NOTES.txt renders without errors
Output includes the release name and namespace
Output shows the correct image name and tag
Output adapts based on the service type (test with --set service.type=ClusterIP vs. --set service.type=NodePort)

Task 3: Multi-Revision Lifecycle Report

Goal: Perform multiple upgrades and a rollback, then document the full revision history to demonstrate your understanding of the Helm release lifecycle.

Instructions

Install the chart:
```
helm install my-webapp webapp
```

Perform three upgrades, changing a value each time:

# Upgrade 1: scale to 3 replicas
helm upgrade my-webapp webapp --set replicaCount=3

# Upgrade 2: change image tag
helm upgrade my-webapp webapp --set replicaCount=3 --set image.tag="2.4-alpine"

# Upgrade 3: switch service to ClusterIP
helm upgrade my-webapp webapp --set replicaCount=3 --set image.tag="2.4-alpine" --set service.type=ClusterIP

View the full history:
```
helm history my-webapp
```
Roll back to revision 2:
```
helm rollback my-webapp 2
```
Document your findings:
- How many revisions exist after the rollback?
- What is the status of each revision?
- What values are active after the rollback? (Use helm get values my-webapp)
Clean up:
```
helm uninstall my-webapp
rm -rf webapp
```

Self-Check

helm history shows 5 revisions (1 install + 3 upgrades + 1 rollback)
The rollback created revision 5, not a restoration of revision 2
The active values after rollback match what was set in revision 2 (replicaCount=3, default image tag)
Only revision 5 has status deployed; all others are superseded

Grading Rubric

Criterion	Points	Description
Task 1: Custom values	30	Chart deploys with custom image, replicas, and service type
Task 1: Rendered output	10	`helm template` output matches expected configuration
Task 2: NOTES.txt template	20	Custom template renders correctly with dynamic values
Task 2: Conditional logic	10	Output adapts based on service type
Task 3: Lifecycle commands	15	All install/upgrade/rollback/uninstall commands succeed
Task 3: History analysis	15	Correct understanding of revision numbering and rollback behavior
Total	100

Stretch Goal

Create a production-values.yaml file that overrides multiple values at once (replicas, resources, service type, ingress settings). Install the chart using helm install my-webapp webapp -f production-values.yaml and verify all overrides are applied with helm get values my-webapp -a.