kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: private-image-test-1
spec:
  containers:
    - name: uses-private-image
      image: $PRIVATE_IMAGE_NAME
      imagePullPolicy: Always
      command: [ "echo", "SUCCESS" ]
EOF
pod/private-image-test-1 created

k8s的配置文件中经常看到有imagePullPolicy属性，这个属性是描述镜像的拉取策略

1. Always 总是拉取镜像
2. IfNotPresent 本地有则使用本地镜像,不拉取
3. Never 只使用本地镜像，从不拉取，即使本地没有
4. 如果省略imagePullPolicy 镜像tag为 :latest 策略为always ，否则 策略为 IfNotPresent

参考

https://kubernetes.io/docs/concepts/containers/images/
https://kubernetes.io/zh/docs/concepts/containers/images/