Install docker under centos8

Install docker under centos8

1. The kernel of the centos system must be higher than 3.10
   command: uname -r to view the centos kernel

2. Update the yum package to the latest
   command: yum update

3. Uninstall the old version (if you have installed the old version, skip this step if you have not installed it before)
   command: yum remove docker docker-common docker-selinux docker-engine

4. Install the required software packages
   Command: yum install -y yum-utils device-mapper-persistent-data lvm2

5. Set yum source
   a: default warehouse address
   command: yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
   b: aliyun warehouse address
   command: yum-config- manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

6. Install the latest version of Docker
   command: yum install docker-ce docker-ce-cli containerd.io

7. The above step 6 may report an error that the version of containerd.io is lower. This is because we only need to update the version of containerd.io. Here I update the following version: https://mirrors.aliyun.com/ docker-ce/linux/centos/7/x86_64/edge/Packages/containerd.io-1.2.13-3.2.el7.x86_64.rpm (skip this step if no error is reported), you can install containerd.io
   command: yum install -y https://mirrors.aliyun.com/docker-ce/linux/centos/7/x86_64/edge/Packages/containerd.io-1.2.13-3.2.el7.x86_64.rpm
   and repeat step 6 above .

8. Start Docker and set boot start
   command: systemctl start docker
   boot self-start command: systemctl enable docker
   start/stop/status command: systemctl start/stop/status docker

9. Modify the Docker service configuration
   vim /usr/lib/systemd/system/docker.service
   to join in ExecStart without a carriage return

-H unix:///var/run/docker.sock -H 0.0.0.0:2375
如：
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock -H unix:///var/run/docker.sock -H 0.0.0.0:2375
# -H unix:///var/run/docker.sock : 开启一个对外主机服务，使用 docker.sock 文件管理
# -H 0.0.0.0:2375 : 允许什么客户端 IP 访问当前服务，当前服务对外暴露的端口号是什么。2375是自定义的端口

Then reload
systemctl daemon-reload
systemctl restart docker

Abnormal x509

Error response from daemon: Get https://registry-1.docker.io/v2/: x509: certificate has expired or is not yet valid

solution:

1. Synchronize time
   vim /etc/chrony.conf Add server 210.72.145.44 iburst server ntp.aliyun.com iburst
   at the end
   
   
2. Reload configuration
   systemctl restart chronyd.service
3. Time synchronization
   chronyc sources -v
4. get time
   date