1. kubectl-convert作用

将yaml资源清单中废弃的api版本或者旧的api版本转换为指定的版本，默认是转换成最新的版本

2. 安装kubectl-convert

根据官网文件安装即可：https://kubernetes.io/zh-cn/docs/tasks/tools/install-kubectl-linux/#install-kubectl-convert-plugin

curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl-convert"
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl-convert.sha256"
echo "$(cat kubectl-convert.sha256) kubectl-convert" | sha256sum --check
install -o root -g root -m 0755 kubectl-convert /usr/local/bin/kubectl-convert

3. 实验

准备一个旧的api版本的yaml文件

kubectl create namespace test

nginx-deploy.yaml:

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: nginx-deploy
  namespace: test
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

kubectl create -f nginx-deploy.yaml

error: resource mapping not found for name: "nginx-deploy" namespace: "test" from "nginx-deploy.yaml": no matches for kind "Deployment" in version "apps/v1beta1"
ensure CRDs are installed first

如上在"apps/v1beta1"未找到Deployment资源，使用kubectl-convert 将api版本更新到最新：

kubectl convert -f nginx-deploy.yaml  > nginx-deploy-v1.yaml

nginx-deploy-v1.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx-deploy
  namespace: test
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 2
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:latest
        imagePullPolicy: Always
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status: {}

api版本已经被修改成：apps/v1了，如果要指定版本使用：kubectl convert -f nginx-deploy.yaml --output-version=apps/v1 > nginx-deploy-v2.yaml

kubectl apply -f nginx-deploy-v1.yaml
kubectl get deploy -n test

NAME           READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deploy   1/1     1            1           76s