Run an app in a container, then expose it so traffic could actually reach it. Two resources handle this: a Deployment and a Service .

Step 1: Writing the Deployment

apiVersion : apps/v1 kind : Deployment metadata : name : my-app spec : replicas : 2 selector : matchLabels : app : my-app template : metadata : labels : app : my-app spec : containers : - name : my-app image : echo-server:latest ports : - containerPort : 80

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This tells Kubernetes to run 2 copies of echo-server and label them app: my-app . The label part matters — I'll need it in a second.

Step 2: Writing the Service

apiVersion : v1 kind : Service metadata : name : my-app-service spec : selector : app : my-app ports : - protocol : TCP port : 80 targetPort : 80 type : ClusterIP

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The selector matches the label I set in the Deployment. That's how Kubernetes knows which pods to send traffic to.…