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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:
  1. Prepare the project structure
  2. Create the Deployment manifest
  3. Apply the Deployment
  4. Verify the rollout and inspect resources

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1. Prepare the directories and files

  1. From your project root, create a folder named deployments.
  2. 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

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

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3. Apply the Deployment

Run: 
kubectl apply -f deployments/deployment.yaml
Or, if you prefer create: 
kubectl create -f deployments/deployment.yaml

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4. Verify the rollout and inspect resources

You can quickly see the status of your Deployment and its Pods:
ActionCommandDescription
List Deploymentskubectl get deploymentsShow READY, UP-TO-DATE, AVAILABLE columns
List all Podskubectl get podsConfirm your Pods are Running
Describe a Deploymentkubectl describe deployment myapp-deploymentView events, strategy, and replica counts
List all resourceskubectl get allGet Pods, Services, Deployments, ReplicaSets
  1. Check the Deployment status 
    kubectl get deployments
    Example output: 
    NAME               READY   UP-TO-DATE   AVAILABLE   AGE
myapp-deployment   3/3     3            3           10s
  2. 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
  3. Describe the Deployment 
    kubectl describe deployment myapp-deployment
    You’ll see details such as desired vs. available replicas, rollout strategy, and recent events:
The image shows a terminal window displaying Kubernetes deployment details for an application named "myapp," including container information, conditions, and events related to scaling the replica set.
  1. 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
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

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