安裝docker的官方步驟，參考docker的官方網站：https://docs.docker.com/engine/install/centos/。
為了保證docker的安裝過程順利，首先要注意部署docker的環境，小編的環境Red Hat Enterprise Linux Server release 7.5，內核：3.10.0-862.el7.x86_64，安裝docker對系統環境要求：centos7.5 64位 內核版本高於3.10，centos6.5 64位 內核版本高於2.6.32，因為內核包含了運行Docker的一些特定修改。
這里簡單描述安裝步驟，詳細步驟請參考官方網站：
- 卸載自帶的包：
1 yum remove docker \
2 docker-client \
3 docker-client-latest \
4 docker-common \
5 docker-latest \
6 docker-latest-logrotate \
7 docker-logrotate \
8 docker-engine
安裝依賴包：
1 yum install -y yum-utils
- 設置鏡像：
1 yum-config-manager \
2 --add-repo \
3 https://download.docker.com/linux/centos/docker-ce.repo
- 執行安裝命令，安裝docker：
1 yum install docker-ce docker-ce-cli containerd.io
- 啟動docker：
1 systemctl start docker
- 輸入docker version來測試docker是否成功安裝：
如果看到上述的client和server，說明兩者均起成功，如果docker只啟動了client，通過輸入service docker start或者systemctl restart docker來開啟server,之后再次輸入docker version來驗證；
完成之后可以用docker測試helloworld，步驟如下：
- 輸入docker pull hello-world來拉取hello-world鏡像
輸入docker run hello-world運行，出現下圖所示內容，說明hello-world運行成功：
小編在安裝的過程中出現版本依賴問題，研究了好久才終於徹底解決。
下面是執行安裝命令的時候出現的問題：
1 [root@localhost ~]# yum install docker-ce docker-ce-cli containerd.io 2 Loaded plugins: langpacks, product-id, search-disabled-repos, subscription-manager 3 This system is not registered with an entitlement server. You can use subscription-manager to register. 4 Resolving Dependencies 5 --> Running transaction check 6 ---> Package containerd.io.x86_64 0:1.4.6-3.1.el7 will be installed 7 --> Processing Dependency: container-selinux >= 2:2.74 for package: containerd.io-1.4.6-3.1.el7.x86_64 8 ---> Package docker-ce.x86_64 3:20.10.7-3.el7 will be installed 9 --> Processing Dependency: container-selinux >= 2:2.74 for package: 3:docker-ce-20.10.7-3.el7.x86_64 10 --> Processing Dependency: docker-ce-rootless-extras for package: 3:docker-ce-20.10.7-3.el7.x86_64 11 ---> Package docker-ce-cli.x86_64 1:20.10.7-3.el7 will be installed 12 --> Processing Dependency: docker-scan-plugin(x86-64) for package: 1:docker-ce-cli-20.10.7-3.el7.x86_64 13 --> Running transaction check 14 ---> Package containerd.io.x86_64 0:1.4.6-3.1.el7 will be installed 15 --> Processing Dependency: container-selinux >= 2:2.74 for package: containerd.io-1.4.6-3.1.el7.x86_64 16 ---> Package docker-ce.x86_64 3:20.10.7-3.el7 will be installed 17 --> Processing Dependency: container-selinux >= 2:2.74 for package: 3:docker-ce-20.10.7-3.el7.x86_64 18 ---> Package docker-ce-rootless-extras.x86_64 0:20.10.7-3.el7 will be installed 19 --> Processing Dependency: fuse-overlayfs >= 0.7 for package: docker-ce-rootless-extras-20.10.7-3.el7.x86_64 20 --> Processing Dependency: slirp4netns >= 0.4 for package: docker-ce-rootless-extras-20.10.7-3.el7.x86_64 21 ---> Package docker-scan-plugin.x86_64 0:0.8.0-3.el7 will be installed 22 --> Finished Dependency Resolution 23 Error: Package: docker-ce-rootless-extras-20.10.7-3.el7.x86_64 (docker-ce-stable) 24 Requires: fuse-overlayfs >= 0.7
25 Error: Package: docker-ce-rootless-extras-20.10.7-3.el7.x86_64 (docker-ce-stable) 26 Requires: slirp4netns >= 0.4
27 Error: Package: 3:docker-ce-20.10.7-3.el7.x86_64 (docker-ce-stable) 28 Requires: container-selinux >= 2:2.74
29 Installed: 2:container-selinux-2.68-1.el7.noarch (@extras) 30 container-selinux = 2:2.68-1.el7 31 Available: 2:container-selinux-2.42-1.gitad8f0f7.el7.noarch (extras) 32 container-selinux = 2:2.42-1.gitad8f0f7.el7 33 Available: 2:container-selinux-2.55-1.el7.noarch (extras) 34 container-selinux = 2:2.55-1.el7 35 Available: 2:container-selinux-2.66-1.el7.noarch (extras) 36 container-selinux = 2:2.66-1.el7 37 Error: Package: containerd.io-1.4.6-3.1.el7.x86_64 (docker-ce-stable) 38 Requires: container-selinux >= 2:2.74
39 Installed: 2:container-selinux-2.68-1.el7.noarch (@extras) 40 container-selinux = 2:2.68-1.el7 41 Available: 2:container-selinux-2.42-1.gitad8f0f7.el7.noarch (extras) 42 container-selinux = 2:2.42-1.gitad8f0f7.el7 43 Available: 2:container-selinux-2.55-1.el7.noarch (extras) 44 container-selinux = 2:2.55-1.el7 45 Available: 2:container-selinux-2.66-1.el7.noarch (extras) 46 container-selinux = 2:2.66-1.el7 47 You could try using --skip-broken to work around the problem 48 You could try running: rpm -Va --nofiles --nodigest
即便是重新安裝 yum reinstall container-selinux ，還是會出現上面的那種提示，其實真正的原因是所配置的yum倉庫的軟件包不是最新的，所以解決辦法就是更換/etc/yum.repos.d/CentOS7-Base-163.repo。小編這里提供下面兩種：
1、中科大(參考地址：http://mirrors.ustc.edu.cn/help/centos.html#)
1 # CentOS-Base.repo 2 # 3 # The mirror system uses the connecting IP address of the client and the 4 # update status of each mirror to pick mirrors that are updated to and 5 # geographically close to the client. You should use this for CentOS updates 6 # unless you are manually picking other mirrors. 7 # 8 # If the mirrorlist= does not work for you, as a fall back you can try the 9 # remarked out baseurl= line instead. 10 # 11 # 12 [base] 13 name=CentOS-$releasever - Base 14 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
15 baseurl=https://mirrors.ustc.edu.cn/centos/$releasever/os/$basearch/
16 gpgcheck=1
17 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
18 #released updates 19 [updates] 20 name=CentOS-$releasever - Updates 21 # mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
22 baseurl=https://mirrors.ustc.edu.cn/centos/$releasever/updates/$basearch/
23 gpgcheck=1
24 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
25 #additional packages that may be useful 26 [extras] 27 name=CentOS-$releasever - Extras 28 # mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
29 baseurl=https://mirrors.ustc.edu.cn/centos/$releasever/extras/$basearch/
30 gpgcheck=1
31 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
32 #additional packages that extend functionality of existing packages 33 [centosplus] 34 name=CentOS-$releasever - Plus 35 # mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
36 baseurl=https://mirrors.ustc.edu.cn/centos/$releasever/centosplus/$basearch/
37 gpgcheck=1
38 enabled=0
39 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
2、清華源
1 # CentOS-Base.repo 2 # 3 # The mirror system uses the connecting IP address of the client and the 4 # update status of each mirror to pick mirrors that are updated to and 5 # geographically close to the client. You should use this for CentOS updates 6 # unless you are manually picking other mirrors. 7 # 8 # If the mirrorlist= does not work for you, as a fall back you can try the 9 # remarked out baseurl= line instead. 10 # 11 # 12 [base] 13 name=CentOS-$releasever - Base 14 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/
15 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
16 gpgcheck=1
17 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
18 #released updates 19 [updates] 20 name=CentOS-$releasever - Updates 21 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/
22 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
23 gpgcheck=1
24 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
25 #additional packages that may be useful 26 [extras] 27 name=CentOS-$releasever - Extras 28 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/
29 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
30 gpgcheck=1
31 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
32 #additional packages that extend functionality of existing packages 33 [centosplus] 34 name=CentOS-$releasever - Plus 35 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/
36 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
37 gpgcheck=1
38 enabled=0
39 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
修改完成后更新yum源：
1 yum clean all 2 rm -rf /var/cache/yum/ 3 yum makecache
這時候，再次執行安裝docker的命令，終於安裝成功了！