下载镜像docker pull时报错：unauthorized: authentication required

下载镜像docker pull时报错：unauthorized: authentication required

具体报错过程：

[root@vl-bg-anaylsis02 ~]# docker pull mysql/mysql-server:5.7
5.7: Pulling from mysql/mysql-server
c7127dfa6d78: Downloading
cb7ddde5230b: Download complete
1528bee07386: Download complete
cca3f8362bb0: Download complete
unauthorized: authentication required

解决方法：

# docker pull 前先登录docker
docker login
然后我在第二天docker pull尽然可以了，估计主要是网络问题

以下是第二天docker pull的结果：

[root@vl-bg-anaylsis02 ~]# docker pull mysql/mysql-server:5.7
5.7: Pulling from mysql/mysql-server
c7127dfa6d78: Pull complete
cb7ddde5230b: Pull complete
1528bee07386: Pull complete
cca3f8362bb0: Pull complete
Digest: sha256:5a5c0841346322ed514a48a7c2ab5409a8106e35718f3195467e7cf52343f25a
Status: Downloaded newer image for mysql/mysql-server:5.7
docker.io/mysql/mysql-server:5.7