Homework

Three tasks that extend the lab exercises into production-grade Service patterns.

Complete all three lab exercises before starting the homework. These tasks build on the chart you created during the lab.

Task 1 — Dual-Service Chart: Public + Internal

Objective

Create a chart that deploys two Services for the same application: a public-facing LoadBalancer and an internal ClusterIP for health checks and metrics.

Instructions

Add a second values block called internalService in values.yaml:

service:
  type: LoadBalancer
  port: 443
  targetPort: 8443
  externalTrafficPolicy: Local
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-scheme: internet-facing

internalService:
  enabled: true
  port: 9090
  targetPort: 9090

Create templates/internal-service.yaml that renders a ClusterIP Service only when internalService.enabled is true
The internal Service must use the same selector labels as the primary Service
Name the internal Service with a -internal suffix
Verify with helm template that both Services render correctly
Install the chart and confirm both Services appear in kubectl get svc
Verify that a test Pod can reach both endpoints

Deliverable

The complete templates/internal-service.yaml and updated values.yaml. Output of helm template showing both Services.

✓ Self-check: Two Services appear. The public Service has type LoadBalancer. The internal Service has type ClusterIP. Setting internalService.enabled=false removes the internal Service entirely.

Task 2 — ExternalName Service for an External Database

Objective

Add a templated ExternalName Service so applications can reference an external database by a stable in-cluster DNS name.

Instructions

Add the following to values.yaml:

externalDB:
  enabled: false
  name: app-database
  host: prod-db.c9abcdef.us-east-1.rds.amazonaws.com

Create templates/external-db-service.yaml:
- Kind: Service with type: ExternalName
- externalName set from .Values.externalDB.host
- No selector, no ports
- Only renders when externalDB.enabled is true

Verify the template renders correctly:

helm template . --set externalDB.enabled=true | grep -A 10 "external"

Install and verify DNS resolution:

kubectl run dns-test --image=busybox:1.36 --rm -it --restart=Never -- \
  nslookup app-database.default.svc.cluster.local

The DNS lookup should return a CNAME pointing to the RDS hostname

Deliverable

The complete templates/external-db-service.yaml template and updated values.yaml. Output of the DNS lookup confirming the CNAME.

✓ Self-check: The ExternalName Service renders only when enabled. nslookup returns the CNAME record. No selector or ports appear in the rendered YAML.

Task 3 — Conditional Headless Service Toggle

Objective

Refactor the headless Service template so it can optionally replace the primary Service (not just supplement it) and expose configurable multi-port definitions.

Instructions

Update values.yaml:

headless:
  enabled: false
  standalone: false    # if true, skip the primary Service
  ports:
    - name: gossip
      port: 7946
      targetPort: 7946
    - name: client
      port: 9042
      targetPort: 9042

Update templates/service.yaml to skip rendering when headless.standalone is true:
```
{{- if not (and .Values.headless.enabled .Values.headless.standalone) }}
```
Update templates/headless-service.yaml to iterate over .Values.headless.ports instead of using the primary Service ports
Verify all four scenarios with helm template:
- headless.enabled=false — only primary Service renders
- headless.enabled=true, standalone=false — both Services render
- headless.enabled=true, standalone=true — only headless Service renders
- Headless Service ports use the headless.ports array, not the primary service.ports

Deliverable

Updated templates/service.yaml, templates/headless-service.yaml, and values.yaml. Output of helm template for all four scenarios.

✓ Self-check: Each scenario produces the correct combination of Services. The headless Service ports match the headless.ports values. No rendering errors occur in any scenario.

Grading Rubric

Criterion	Points	Description
Task 1: Dual-Service	35	Both Services render with correct types, selectors, and conditional logic
Task 2: ExternalName	25	ExternalName Service renders correctly, DNS resolves the CNAME, conditional toggle works
Task 3: Headless toggle	30	All four scenarios produce correct output, ports are independently configurable
Code quality	10	Consistent naming, proper use of helpers, clean YAML output with no extra whitespace

Submission Checklist

✓ Task 1: internal-service.yaml template and dual-Service helm template output
✓ Task 2: external-db-service.yaml template and DNS lookup proof
✓ Task 3: Updated headless template with standalone mode and four-scenario verification
✓ All templates pass helm lint without warnings