Deployment Strategy
===
The stratgey to ensure uninterrupted service is to use a Strategy and a ReadinessProbe. The readiness probe will ensure the new pod is up and running before removing the old pod. See Kubernetes documentation.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-dep
  namespace: default
spec:
  replicas: 2
  strategy:
  type: RollingUpdate
  rollingUpdate:
    maxSurge: 1
    maxUnavailable: 25%
  selector:
    matchLabels:
      app: hello-dep
  template:
    metadata:
      labels:
        app: hello-dep
    spec:
      containers:
      - image: gcr.io/google-samples/hello-app:2.0
        imagePullPolicy: Always
        name: hello-dep
        ports:
        - containerPort: 8080
        readinessProbe:
          httpGet:
             path: /
             port: 8080
             initialDelaySeconds: 5
             periodSeconds: 5
             successThreshold: 1