Challenge, Medium,  on  Kubernetes

Schedule Pods Using Required Pod Affinity

Scenario

You have an existing Deployment named db-app running in the db namespace with 3 replicas using the mysql image. The pods are labeled with app=db.

Create a new Deployment named web-app in the web namespace using the image httpd:trixie with 2 replicas, and ensure that the pods are labeled with app=web-app.

Configure the Deployment so that its pods are scheduled only on nodes where pods with the label app=db are already running by using required pod affinity with the topologyKey set to kubernetes.io/hostname.

Do not modify the existing db-app Deployment. Ensure the web-app pods remain in the Running state and verify that they are scheduled on the same nodes as the db-app pods.

Do not use taints, tolerations, or node selectors. Use only Pod Affinity to control pod scheduling.

Hint

You need to add affinity.podAffinity.requiredDuringSchedulingIgnoredDuringExecution to the web-app Deployment spec. Use topologyKey: kubernetes.io/hostname and match the label app=db to co-locate with db-app pods.

💡Test Cases

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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 schedule-pods-using-required-pod-affinity-d0ede94e

This will create a local copy of the challenge content in a directory named schedule-pods-using-required-pod-affinity-d0ede94e. You only need to do this once per challenge.

Stream your changes

labctl content push -fw challenge schedule-pods-using-required-pod-affinity-d0ede94e

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

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