K8s Pod容器中的command和args指令详解

[root@master01 ~]# kubectl explain pod.spec.containers.command
KIND:     Pod
VERSION:  v1
FIELD:    command <[]string>
DESCRIPTION:
     Entrypoint array. Not executed within a shell. The container image's
     ENTRYPOINT is used if this is not provided. Variable references $(VAR_NAME)
     are expanded using the container's environment. If a variable cannot be
     resolved, the reference in the input string will be unchanged. Double $$
     are reduced to a single $, which allows for escaping the $(VAR_NAME)
     syntax: i.e. "$$(VAR_NAME)" will produce the string literal "$(VAR_NAME)".
     Escaped references will never be expanded, regardless of whether the
     variable exists or not. Cannot be updated. More info:
     https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell

[root@master01 ~]# kubectl explain pod.spec.containers.args
KIND:     Pod
VERSION:  v1
FIELD:    args <[]string>
DESCRIPTION:
     Arguments to the entrypoint. The container image's CMD is used if this is
     not provided. Variable references $(VAR_NAME) are expanded using the
     container's environment. If a variable cannot be resolved, the reference in
     the input string will be unchanged. Double $$ are reduced to a single $,
     which allows for escaping the $(VAR_NAME) syntax: i.e. "$$(VAR_NAME)" will
     produce the string literal "$(VAR_NAME)". Escaped references will never be
     expanded, regardless of whether the variable exists or not. Cannot be
     updated. More info:
     https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell

# 定义资源清单
[root@master01 ~/pod]# cat command-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: command-demo
  labels:
    purpose: demonstrate-command
spec:
  containers:
  - name: command-demo-container
    image: debian
    command: ["printenv"]
    args: ["HOSTNAME", "KUBERNETES_PORT"]
  restartPolicy: OnFailure
# 创建pod
[root@master01 ~/pod]# kubectl apply -f command-pod.yaml
pod/command-demo created
# 查看Pod日志打印信息
[root@master01 ~/pod]# kubectl logs command-demo
command-demo
tcp://10.96.0.1:443