Homework
Lesson 07 — Deployments & StatefulSets
Instructions
Complete all three tasks. Use helm template to verify rendered output before installing. Use the grading table at the bottom to self-assess your work.
Task 1 — Blue-Green Deployment Toggle
Extend your Deployment template to support both RollingUpdate and Recreate strategies, selectable from values.yaml. Add a conditional block so that rollingUpdate parameters are only rendered when the strategy type is RollingUpdate.
Requirements
- The strategy type must be configurable via
.Values.strategy.type maxSurgeandmaxUnavailablemust only appear whenstrategy.typeisRollingUpdate- Both values must have sensible defaults (e.g.,
maxSurge: 1,maxUnavailable: 0) - Include an init container that runs only when
.Values.initContainers.migrate.enabledis true. It should execute asleep 5command to simulate a migration
Verification
# Should show rollingUpdate parameters
helm template . --set strategy.type=RollingUpdate | grep -A 3 rollingUpdate
# Should NOT show rollingUpdate parameters
helm template . --set strategy.type=Recreate | grep rollingUpdate
# (expect no output)Task 2 — StatefulSet with Configurable Storage
Create a StatefulSet template for a PostgreSQL workload with the following features:
- A headless Service for stable DNS
volumeClaimTemplateswith configurablestorageClassName,accessModes, andstoragesize- Environment variables sourced from a Secret (
POSTGRES_PASSWORD) and a ConfigMap (POSTGRES_DB) - A startup probe on port 5432 using
tcpSocket - A PodDisruptionBudget that ensures at least 1 replica is always available
Provide a values.yaml snippet
postgresql:
replicas: 3
image: postgres:16-alpine
storageClass: standard
storageSize: 5Gi
pdb:
minAvailable: 1Verification
# Rendered output should contain volumeClaimTemplates
helm template . | grep -A 10 volumeClaimTemplates
# PDB should reference correct selector labels
helm template . | grep -A 8 "kind: PodDisruptionBudget"Task 3 — Multi-Environment Values Override
Create three values files for different environments. Each must configure the Deployment and (optionally) the StatefulSet with appropriate settings:
| File | Replicas | Resources | Strategy | PDB |
|---|---|---|---|---|
values-dev.yaml |
1 | requests: 50m CPU, 64Mi memory; no limits | Recreate | disabled |
values-staging.yaml |
2 | requests: 100m CPU, 128Mi; limits: 250m CPU, 256Mi | RollingUpdate (maxSurge: 1, maxUnavailable: 1) | maxUnavailable: 1 |
values-prod.yaml |
5 | requests: 250m CPU, 256Mi; limits: 1 CPU, 1Gi | RollingUpdate (maxSurge: 2, maxUnavailable: 0) | minAvailable: 4 |
Production must also include:
- Topology spread constraints across zones (
topology.kubernetes.io/zone) withmaxSkew: 1andDoNotSchedule - All three probe types configured
Verification
# Compare rendered output across environments
helm template . -f values-dev.yaml | grep replicas
helm template . -f values-staging.yaml | grep replicas
helm template . -f values-prod.yaml | grep -A 4 topologySpreadConstraintsGrading Rubric
| Criterion | Points | How to Verify |
|---|---|---|
Task 1: Strategy toggle works — rollingUpdate block absent with Recreate |
10 | helm template . --set strategy.type=Recreate has no rollingUpdate key |
| Task 1: Init container conditional renders correctly | 5 | helm template . --set initContainers.migrate.enabled=true shows init container |
| Task 1: Defaults applied for maxSurge/maxUnavailable when not set | 5 | helm template . shows default values in rollingUpdate block |
| Task 2: StatefulSet renders with volumeClaimTemplates | 10 | Rendered YAML contains volumeClaimTemplates with correct storage class and size |
Task 2: Headless Service has clusterIP: None |
5 | helm template . shows headless service |
| Task 2: Env vars sourced from Secret and ConfigMap | 5 | Rendered pod spec contains secretKeyRef and configMapKeyRef |
| Task 2: PDB with minAvailable: 1 | 5 | helm template . shows PDB with minAvailable: 1 |
| Task 2: Startup probe on TCP 5432 | 5 | Rendered StatefulSet contains tcpSocket startup probe |
| Task 3: Three environment files produce correct replica counts | 10 | Template output shows 1, 2, and 5 replicas respectively |
| Task 3: Production includes topology spread with zone constraint | 10 | helm template . -f values-prod.yaml shows topologySpreadConstraints |
| Task 3: Resource differences across environments are correct | 10 | Diff rendered output for each environment |
| Task 3: PDB disabled in dev, configured in staging/prod | 5 | Dev output has no PDB; staging/prod have correct PDB values |
All templates pass helm lint |
10 | helm lint . and helm lint . -f values-prod.yaml report no errors |
| Total | 95 | |
| Bonus: Templates install successfully in a live cluster | +5 | helm install succeeds and pods reach Ready state |
Submission
Ensure all files pass helm lint without errors. Run helm template . -f values-prod.yaml and review the full rendered output to confirm correctness before submitting.