使用阿里云对docker拉取镜像加速

使用docker的时候，总是需要去search镜像，使用国外的源下载太慢，还有诸多的限制，无意中发现可以使用阿里云进行加速，实测有用，废话少说，操作如下：

1.打开阿里云控制台，没有的可以用淘宝账号或者支付宝账号直接登录

https://cr.console.aliyun.com/cn-hangzhou/instances/mirrors

打开容器镜像服务，镜像加速器，复制加速地址后，按照第二个红框所示，完成配置。

2.重启docker

systemctl daemon-reload

systemctl restart docker

OK!加速完成，嗖嗖嗖！！！

tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["https://c8it25aj.mirror.aliyuncs.com"]
}
EOF
systemctl daemon-reload && systemctl restart docker

发现一个小bug： 修改daemon.json文件导致docker不能启动

网上大部分说是daemon.json的文件配置的有问题，有的说是docker软件包的问题，可实际上是没有问题的，最后通过修改/usr/lib/systemd/system/docker.service文件来解决了

[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target firewalld.service
Wants=network-online.target

[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker

# docker-18.03
ExecStart=/usr/bin/dockerd --data-root=/data/docker 删除掉这里的地址，这里会导致源与ali源冲突

ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
# restart the docker process if it exits prematurely
"/usr/lib/systemd/system/docker.service" 36L, 1183C