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In this walkthrough, you’ll learn how to convert an existing ReplicaSet into a fully managed Deployment. Deployments offer declarative updates, rollbacks, and scaling capabilities—making them the recommended way to run replicas in production. We’ll:

Prepare the project structure
Create the Deployment manifest
Apply the Deployment
Verify the rollout and inspect resources

1. Prepare the directories and files

From your project root, create a folder named deployments.
Inside deployments, create a file called deployment.yaml.

To see what we’re building on, here’s the reference ReplicaSet we defined earlier:

# replicaset.yaml (for reference)
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: myapp-replicaset
  labels:
    app: myapp
spec:
  selector:
    matchLabels:
      app: myapp
  replicas: 4
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: nginx
        image: nginx

2. Create the Deployment manifest

Copy the spec from the ReplicaSet into deployments/deployment.yaml, then:

Change kind to Deployment
Set metadata.name and labels to match your application
Adjust replicas to 3 (or your desired count)

# deployments/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deployment
  labels:
    tier: frontend
    app: myapp
spec:
  replicas: 3
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: nginx
        image: nginx

Note

The selector.matchLabels field must exactly match the labels on the Pod template. Otherwise, Kubernetes won’t know which Pods belong to this Deployment.

3. Apply the Deployment

Run:

kubectl apply -f deployments/deployment.yaml

Or, if you prefer create:

kubectl create -f deployments/deployment.yaml

4. Verify the rollout and inspect resources

You can quickly see the status of your Deployment and its Pods:

Action	Command	Description
List Deployments	`kubectl get deployments`	Show READY, UP-TO-DATE, AVAILABLE columns
List all Pods	`kubectl get pods`	Confirm your Pods are Running
Describe a Deployment	`kubectl describe deployment myapp-deployment`	View events, strategy, and replica counts
List all resources	`kubectl get all`	Get Pods, Services, Deployments, ReplicaSets

Check the Deployment status

kubectl get deployments

Example output:

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
myapp-deployment   3/3     3            3           10s

List the Pods

kubectl get pods

Example output:

NAME                                    READY   STATUS    RESTARTS   AGE
myapp-deployment-5d8fcb5b6c-abc         1/1     Running   0          30s
myapp-deployment-5d8fcb5b6c-def         1/1     Running   0          30s
myapp-deployment-5d8fcb5b6c-ghi         1/1     Running   0          30s

Describe the Deployment
```
kubectl describe deployment myapp-deployment
```
You’ll see details such as desired vs. available replicas, rollout strategy, and recent events:

View all objects in the namespace

kubectl get all

Example output:

NAME                                   READY   STATUS    RESTARTS   AGE
pod/myapp-deployment-5d8fcb5b6c-abc    1/1     Running   0          1m
pod/myapp-deployment-5d8fcb5b6c-def    1/1     Running   0          1m
pod/myapp-deployment-5d8fcb5b6c-ghi    1/1     Running   0          1m

NAME                     TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/kubernetes       ClusterIP   10.96.0.1      <none>        443/TCP   15m

NAME                               READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/myapp-deployment   3/3     3            3           1m

NAME                                          DESIRED   CURRENT   READY   AGE
replicaset.apps/myapp-deployment-5d8fcb5b6c   3         3         3       1m

Next Steps

To roll out updates, modify spec.template.spec.containers[].image and run:

kubectl apply -f deployments/deployment.yaml

Then track progress with:

kubectl rollout status deployment/myapp-deployment

Links and References

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