第一步，编写首次部署所需的yaml文件，包括三块：命名空间定义、服务定义、部署定义，nginx的镜像版本为 1.16.1

内容如下：

apiVersion: v1
kind: Namespace
metadata:
  name: load-balance

---

kind: Service
apiVersion: v1
metadata:
  labels:
    app: nginx-1161
  name: nginx-1161
  namespace: load-balance
spec:
  type: NodePort
  ports:
    - port: 80
      targetPort: 80
      nodePort: 30012
  selector:
    app: nginx-1161

---

kind: Deployment
apiVersion: apps/v1
metadata:
  labels:
    app: nginx-1161
  name: nginx-1161
  namespace: load-balance
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx-1161
  template:
    metadata:
      labels:
        app: nginx-1161
    spec:
      containers:
      - name: nginx
        image: nginx:1.16.1
        imagePullPolicy: IfNotPresent
        ports:
        - containerPort: 80
          protocol: TCP

# 执行创建
$ kubectl apply -f ./nginx-deployment.yaml 
namespace/load-balance created
service/nginx-