World K2: Trays & Orders

Deployments: the standing order

You will learn: how a Deployment, its ReplicaSet and its pods fit together.

Checked with Kubernetes 1.37 on 31 Oct 2026

The problem

A ReplicaSet keeps 3 trays of nginx 1.29. The menu moves to 1.30, so you edit its template. What happens to the 3 trays already out?

Watch

You are here: cluster kind-dev namespace default

~/shop $ kubectl apply -f shop.yamldeployment.apps/shop created~/shop $ kubectl rollout status deployment/shop --timeout=120sWaiting for deployment "shop" rollout to finish: 0 of 3 updated replicas are available...deployment "shop" successfully rolled out~/shop $ kubectl get deploy,rs,podsNAME                   READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/shop   3/3     3            3           10sNAME                             DESIRED   CURRENT   READY   AGEreplicaset.apps/shop-747bf9cf8   3         3         3       10sNAME                       READY   STATUS    RESTARTS   AGEpod/shop-747bf9cf8-9wfbg   1/1     Running   0          10spod/shop-747bf9cf8-gqqzd   1/1     Running   0          10spod/shop-747bf9cf8-wxnbw   1/1     Running   0          10s

A is the manager’s standing order: “always 3 trays of this dish”. It makes a ReplicaSet, which makes the pods. Three layers, one file.

Try it

Who makes whom? Put the one you write at the top.

The one you write at the top. Put these in order. Use the arrows, or drag.

ReplicaSet shop-747bf9cf8: the Deployment makes it
Pods shop-747bf9cf8-…: the ReplicaSet makes them
Deployment shop: you write this

Try it

Your turn. Apply shop.yaml. When all 3 trays are up, change the order to 4.

You are here: cluster kind-dev namespace default

Want0written on the order for shop

See00 ready

Do All goodGaps fixed: 0

dev-control-planeOpenManager

No trays here.

dev-workerOpen

No trays here.

dev-worker2Open

No trays here.

Time: +0s (sped up)

Hint

kubectl apply -f shop.yaml, then kubectl scale deployment shop --replicas=4.

Predict

Someone deletes the ReplicaSet shop-747bf9cf8. Its 3 trays go with it. What does the Deployment do?

Check

You are here: cluster kind-dev namespace default

~/shop $ kubectl apply -f shop.yamldeployment.apps/shop created~/shop $ kubectl rollout status deployment/shop --timeout=120sWaiting for deployment "shop" rollout to finish: 0 of 3 updated replicas are available...deployment "shop" successfully rolled out~/shop $ kubectl delete rs -l app=shopreplicaset.apps "shop-747bf9cf8" deleted from default namespace~/shop $ kubectl rollout status deployment/shop --timeout=120sWaiting for deployment "shop" rollout to finish: 0 of 3 updated replicas are available...deployment "shop" successfully rolled out~/shop $ kubectl get rsNAME             DESIRED   CURRENT   READY   AGEshop-747bf9cf8   3         3         3       7s

The ReplicaSet came back with the same name. Its name comes from the template, so same template, same name. The trays inside are new.

You did it!

You can now explain how a Deployment, its ReplicaSet and its pods fit together.

Go deeper (optional)

Read a pod name from the left. shop is the Deployment. 747bf9cf8 comes from the template (the pod-template-hash label). The last part is random. To close the shop for good, delete the Deployment, not its pods.

Real rep (optional): on a throwaway cluster, run kubectl get deploy,rs,pods --show-labels.