Challenge, Medium,  on  Kubernetes

Create a Redis StatefulSet with Stable Pod Identities and Persistent Storage

Scenario

You are setting up a distributed caching system in namespace coral. The system requires a StatefulSet so that each cache node gets a stable identity and its own dedicated storage. A Headless Service is required so that each Pod is individually addressable by DNS.

Task

In namespace coral, create a Headless Service named cache-headless with clusterIP: None, selector role: cache, and port 6379.

Then create a StatefulSet named cache-nodes with the following configuration:

  • 4 replicas of redis:alpine
  • container named cache on port 6379
  • volumeClaimTemplate named cache-storage requesting 128Mi storage with storageClassName: local-path
  • serviceName set to cache-headless.

Confirm the Pods come up with sequential names cache-nodes-0 through cache-nodes-3.

Ensure all StatefulSet Pods are running.

Hint 1

A StatefulSet requires a Headless Service (clusterIP: None) to provide stable network identities for its Pods.

The serviceName in the StatefulSet must match this Service, and each Pod receives a predictable DNS name in the form <pod-name>.<service-name>.<namespace>.svc.cluster.local.

Create the Headless Service before the StatefulSet, since the StatefulSet references it by name.

Use volumeClaimTemplates so that each Pod automatically gets its own dedicated PersistentVolumeClaim with persistent storage.

See the official docs: StatefulSets

Test Cases

How to Author Challenges on iximiuz Labs

Instead of providing a subpar online editing experience, iximiuz Labs offers a helper CLI tool called labctl, allowing you to use your favorite text editor (or a full-featured IDE) to write content from the comfort of your local machine.

Install labctl CLI

curl -sf https://labs.iximiuz.com/cli/install.sh | sh

This will download and install the latest version of the labctl CLI. You only need to do this once per workstation.

Authorize labctl

labctl auth login

This will open a browser window asking you to authorize labctl to access your account. You need to do it after a fresh install of labctl and repeat it whenever the auth session expires.

Pull challenge content

labctl content pull challenge create-a-redis-statefulset-with-stable-pod-identities-storage-4dcaf99e

This will create a local copy of the challenge content in a directory named create-a-redis-statefulset-with-stable-pod-identities-storage-4dcaf99e. You only need to do this once per challenge.

Stream your changes

labctl content push -fw challenge create-a-redis-statefulset-with-stable-pod-identities-storage-4dcaf99e

Run this command in a separate terminal to continuously upload your changes to the server while editing the challenge in your favorite text editor or IDE.

You can also use labctl to create, list, and delete your content. Learn more about the available commands: labctl content --help

Start challenge