今天在对ubuntu18.04服务器进行apt update更新的时候，日志报错了
W: GPG error: https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6Axxxxxxxxxxxx
E: The repository 'https://mirrors.aliyun.com/kubernetes/apt kubernetes-xenial InRelease' is not signed.
解决方案：
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6Axxxxxxxxxx
重新update即可
