2.1 在ubuntu中安装
在linux系统中安装Docker非常简单，官方为我们提供了一键安装脚本。这个方法也适用于Debian或CentOS等发行版。
curl -sSL https://get.daocloud.io/docker | sh
安装过程如果出现超时，不要灰心，多试几次，总会成功的。安装完成后，Docker只能被root用户使用，可以使用下面的命令取消权限限制：
sudo gpasswd -a <你的用户名> docker
然后，重启docker服务：
sudo service docker restart
最后，关闭当前的命令行，重新打开新的命令行就可以了。
顺便提一下，如果在CentOS下安装，可能会出现一堆类似于下面的错误：
问题 1: problem with installed package podman-2.0.5-5.module_el8.3.0+512+b3b58dca.x86_64 - package podman-2.0.5-5.module_el8.3.0+512+b3b58dca.x86_64 requires runc >= 1.0.0-57, but none of the providers can be installed - package podman-3.0.1-6.module_el8.4.0+781+acf4c33b.x86_64 requires runc >= 1.0.0-57, but none of the providers can be installed - package podman-3.0.1-7.module_el8.4.0+830+8027e1c4.x86_64 requires runc >= 1.0.0-57, but none of the providers can be installed - package containerd.io-1.4.6-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - cannot install the best candidate for the job - package runc-1.0.0-64.rc10.module_el8.4.0+522+66908d0c.x86_64 is filtered out by modular filtering - package runc-1.0.0-65.rc10.module_el8.4.0+819+4afbd1d6.x86_64 is filtered out by modular filtering - package runc-1.0.0-70.rc92.module_el8.4.0+786+4668b267.x86_64 is filtered out by modular filtering - package runc-1.0.0-71.rc92.module_el8.4.0+833+9763146c.x86_64 is filtered out by modular filtering 问题 2: package podman-3.0.1-6.module_el8.4.0+781+acf4c33b.x86_64 requires runc >= 1.0.0-57, but none of the providers can be installed - package containerd.io-1.4.3-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.3-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.3-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package containerd.io-1.4.3-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package docker-ce-3:20.10.7-3.el8.x86_64 requires containerd.io >= 1.4.1, but none of the providers can be installed - package containerd.io-1.4.3-3.2.el8.x86_64 conflicts with runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.3-3.2.el8.x86_64 obsoletes runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.3-3.2.el8.x86_64 conflicts with runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package containerd.io-1.4.3-3.2.el8.x86_64 obsoletes runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package podman-catatonit-3.0.1-6.module_el8.4.0+781+acf4c33b.x86_64 requires podman = 3.0.1-6.module_el8.4.0+781+acf4c33b, but none of the providers can be installed - problem with installed package podman-catatonit-2.0.5-5.module_el8.3.0+512+b3b58dca.x86_64 - package podman-catatonit-3.0.1-7.module_el8.4.0+830+8027e1c4.x86_64 requires podman = 3.0.1-7.module_el8.4.0+830+8027e1c4, but none of the providers can be installed - package podman-3.0.1-7.module_el8.4.0+830+8027e1c4.x86_64 requires runc >= 1.0.0-57, but none of the providers can be installed - package containerd.io-1.4.3-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.3-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.3-3.2.el8.x86_64 conflicts with runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.3-3.2.el8.x86_64 obsoletes runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.4-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.4-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-68.rc92.module_el8.3.0+475+c50ce30b.x86_64 - cannot install the best candidate for the job - package runc-1.0.0-64.rc10.module_el8.4.0+522+66908d0c.x86_64 is filtered out by modular filtering - package runc-1.0.0-65.rc10.module_el8.4.0+819+4afbd1d6.x86_64 is filtered out by modular filtering - package runc-1.0.0-70.rc92.module_el8.4.0+786+4668b267.x86_64 is filtered out by modular filtering - package runc-1.0.0-71.rc92.module_el8.4.0+833+9763146c.x86_64 is filtered out by modular filtering - package containerd.io-1.4.4-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.4-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.4-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package containerd.io-1.4.4-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-70.rc92.module_el8.4.0+673+eabfc99d.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 conflicts with runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package containerd.io-1.4.6-3.1.el8.x86_64 obsoletes runc provided by runc-1.0.0-73.rc93.module_el8.4.0+830+8027e1c4.x86_64 - package podman-catatonit-2.0.5-5.module_el8.3.0+512+b3b58dca.x86_64 requires podman = 2.0.5-5.module_el8.3.0+512+b3b58dca, but none of the providers can be installed - package podman-2.0.5-5.module_el8.3.0+512+b3b58dca.x86_64 requires runc >= 1.0.0-57, but none of the providers can be installed
这是由于docker和Podman冲突造成的，需要先卸载Podman：
yum erase podman buildah
2.2 在Win10中安装
Docker的运行，依赖linux的环境，官方提供了Docker Desktop for Windows，但是它需要安装Hyper-V，Hyper-V是微软开发的虚拟机，类似于 VMWare 或 VirtualBox，仅适用于 Windows 10。这个虚拟机一旦启用，QEMU、VirtualBox 或 VMWare Workstation 15 及以下版本将无法使用！如果你必须在电脑上使用其他虚拟机（例如开发 Android 应用必须使用的模拟器），请不要使用 Hyper-V！
我的电脑是win10家庭版，不能直接安装hyper-v，需要将下面的命令保存到cmd文件中：
pushd "%~dp0" dir /b %SystemRoot%\servicing\Packages\*Hyper-V*.mum >hyper-v.txt for /f %%i in ('findstr /i . hyper-v.txt 2^>nul') do dism /online /norestart /add-package:"%SystemRoot%\servicing\Packages\%%i" del hyper-v.txt Dism /online /enable-feature /featurename:Microsoft-Hyper-V-All /LimitAccess /ALL
然后在cmd文件上点击右键，选择使用管理员运行。执行完毕后会重启，在重启的过程中进行安装。
2.3 Hello world
docker服务启动的情况下，运行下面的命令：
docker run ubuntu:20.04 /bin/echo "Hello world"
此命令的含义是：
- docker run：运行docker镜像命令
- ubuntu:20.04：镜像名称为ubuntu版本号为20.04
- /bin/echo “Hello world”：运行参数，此镜像的参数含义为运行镜像的echo命令显示hello world
第一次运行时，因为本地没有ubuntu:20.04镜像，docker会自动从镜像服务器下载。下载过程可能需要多试几次，只要成功一次，以后执行就不再需要下载了。
docker官方还提供了一个hello-world镜像，可以直接运行：
docker run hello-world
此命令省略了镜像版本和运行参数，docker使用latest作为版本，即最新版本。
从hello world的例子中，也可以体验到，docker实例的运行是非常快的。
