一、 环境准备

IP	主机名	操作系统版本	docker版本
192.168.168.128	master01	CentOS Linux release 7.9.2009 (Core)	docker-20.10.15.tgz

二、安装

# 安装包获取
cd /root
wget -c https://download.docker.com/linux/static/stable/x86_64/docker-20.10.15.tgz
[root@master01 ~]# ll  docker-20.10.15.tgz
-rw-r--r--. 1 root root 64928849 Aug  3 06:58 docker-20.10.15.tgz
[root@master01 ~]#
# 解压
tar -zxvf docker-20.10.15.tgz
mkdir  -p /usr/local/bin/
mv /root/docker/* /usr/local/bin/

三、dockerd启动参数详解

配置选项	默认值	描述
–config-file	/etc/docker/daemon.json	dockerd启动的配置文件路径
–containerd	/run/containerd/containerd.sock	dockerd启动的时候会自动启动containerd，containerd会监听此unix sock ，dockerd会通过此sock文件与containerd通信
–containerd-namespace	moby	containerd的命名空间
-H, --host list	/var/run/docker.sock	dockerd监听的unix sock的路径，用于接收客户端的请求
–exec-opt	–exec-opt native.cgroupdriver=cgroupfs	docker所使用的cgroup driver，默认是cgroupfs

dockerd进程（Docker daemon） 能通过三种方式进行监听，unix, tcp, 和 fd。默认方式是通过unix 套接字进行监听，该sock监听文件的默认路径为 /var/run/docker.sock。该sock方式只能本地访问，如果想要远程访问，就需要使用tcp的方式，tcp的监听方式为：-H tcp://ip:2375。dockerd也可以同时使用多种监听方式，示例如下：

dockerd -H unix:///var/run/docker.sock -H tcp://192.168.59.106 -H tcp://10.10.10.2

dockerd 指定配置文件启动

dockerd  --config-file /run/docker/daemon.json

cat << EOF > /etc/docker/daemon.json	
{"exec-opts": ["native.cgroupdriver=systemd"],"registry-mirrors": ["https://registry.hub.docker.com","http://hub-mirror.c.163.com","https://docker.mirrors.ustc.edu.cn","https://registry.docker-cn.com"]}
EOF

四、配置systemd服务

 cat <<EOF > /usr/lib/systemd/system/docker.service
[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
ExecStart=/usr/local/bin/dockerd
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
Restart=on-failure
StartLimitBurst=3
StartLimitInterval=60s[Install]
WantedBy=multi-user.target
EOF

注意
dockerd相关的执行程序请放在/usr/local/bin/ 路径下，因为该路径存在于systemd服务管理中的PATH环境变量中，如果存放于其他路径中，systemctl启动会报错。

启动服务

在使用systemctl启动服务之前，需要先把firewalld服务关闭，否则会无法启动docker服务；如果直接命令行启动dockerd，则不会报错，具体原因还未找到…

systemctl stop firewalld
systemctl  daemon-reload
systemctl start docker