Docker学习笔记二：安装Docker并管理镜像

安装并运行hello-world

安装Docker（以CentOS 7.x为例）

安装前须知：Docker需要64位操作系统和3.10或更高版本的Linux内核。

使用如下命令检查当前内核版本：

$ uname -r
3.10.0-229.el7.x86_64

推荐将系统更新到最新。

1、确保系统更新到了最新：

$ sudo yum update -y

2、添加yum仓库：

$ sudo tee /etc/yum.repos.d/docker.repo <<-'EOF'
[dockerrepo]
name=Docker Repository
baseurl=https://yum.dockerproject.org/repo/main/centos/7/
enabled=1
gpgcheck=1
gpgkey=https://yum.dockerproject.org/gpg
EOF

3、安装Docker包：

$ sudo yum install docker-engine

4、启用服务：

$ sudo systemctl enable docker.service

5、启动Docker守护进程：

$ sudo systemctl start docker

验证安装

1.在命令行执行

docker version

：

$ docker version
Client:
Version:      1.12.3
API version:  1.24
Go version:   go1.6.3
Git commit:   6b644ec
Built:
OS/Arch:      linux/amd64

Server:
Version:      1.12.3
API version:  1.24
Go version:   go1.6.3
Git commit:   6b644ec
Built:
OS/Arch:      linux/amd64

2.输入

docker run ubuntu /bin/echo 'hello-world'

命令并回车：

$ docker run ubuntu /bin/echo 'hello world'
Unable to find image 'ubuntu:latest' locally
latest: Pulling from library/ubuntu
cad964aed91d: Pull complete
3a80a22fea63: Pull complete
50de990d7957: Pull complete
61e032b8f2cb: Pull complete
9f03ce1741bf: Pull complete
Digest: sha256:28d4c5234db8d5a634d5e621c363d900f8f241240ee0a6a978784c978fe9c737
Status: Downloaded newer image for ubuntu:latest
hello world

查看到这些信息，则证明安装完成。

若刚安装完Docker或者本地没有ubuntu镜像，docker会从Docker hub下载ubuntu image并运行一个容器，执行完

/bin/echo 'hello world'

命令执行完成后容器退出。

镜像管理

列出主机上已有的镜像

$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ubuntu              latest              c73a085dc378        28 hours ago        127.1 MB
composetest_web     latest              b241384399ea        5 days ago          682.4 MB
web                 latest              11dd84ade57e        5 days ago          682.4 MB
<none>              <none>              60803d8976d7        5 days ago          675.3 MB
python              2.7                 4c5f5839b372        3 weeks ago         675.3 MB
redis               latest              0d1cbfaa41da        4 weeks ago         185 MB
mysql               5.7.14              4b3b6b994512        5 weeks ago         384.5 MB
hello-world         latest              c54a2cc56cbb        12 weeks ago        1.848 kB
medicean/vulapps    latest              689d86032c20        3 months ago        360.1 MB
nginx               latest              0d409d33b27e        3 months ago        182.8 MB
training/webapp     latest              6fae60ef3446        16 months ago       348.8 MB

搜索在线Docker image

$ docker search ubuntu
NAME                              DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
ubuntu                            Ubuntu is a Debian-based Linux operating s...   4771      [OK]
ubuntu-upstart                    Upstart is an event-based replacement for ...   66        [OK]
rastasheep/ubuntu-sshd            Dockerized SSH service, built on top of of...   42                   [OK]
ubuntu-debootstrap                debootstrap --variant=minbase --components...   27        [OK]
torusware/speedus-ubuntu          Always updated official Ubuntu docker imag...   27                   [OK]
nickistre/ubuntu-lamp             LAMP server on Ubuntu                           9                    [OK]
nuagebec/ubuntu                   Simple always updated Ubuntu docker images...   8                    [OK]
nickistre/ubuntu-lamp-wordpress   LAMP on Ubuntu with wp-cli installed            6                    [OK]
nimmis/ubuntu                     This is a docker images different LTS vers...   5                    [OK]
maxexcloo/ubuntu                  Base image built on Ubuntu with init, Supe...   2                    [OK]
darksheer/ubuntu                  Base Ubuntu Image -- Updated hourly             1                    [OK]
admiringworm/ubuntu               Base ubuntu images based on the official u...   1                    [OK]
jordi/ubuntu                      Ubuntu Base Image                               1                    [OK]
lynxtp/ubuntu                     https://github.com/lynxtp/docker-ubuntu         0                    [OK]
life360/ubuntu                    Ubuntu is a Debian-based Linux operating s...   0                    [OK]
widerplan/ubuntu                  Our basic Ubuntu images.                        0                    [OK]
esycat/ubuntu                     Ubuntu LTS                                      0                    [OK]
datenbetrieb/ubuntu               custom flavor of the official ubuntu base ...   0                    [OK]
webhippie/ubuntu                  Docker images for ubuntu                        0                    [OK]
teamrock/ubuntu                   TeamRock's Ubuntu image configured with AW...   0                    [OK]
dorapro/ubuntu                    ubuntu image                                    0                    [OK]
uvatbc/ubuntu                     Ubuntu images with unprivileged user            0                    [OK]
konstruktoid/ubuntu               Ubuntu base image                               0                    [OK]
ustclug/ubuntu                    ubuntu image for docker with USTC mirror        0                    [OK]
gopex/ubuntu                      Automatic build of GoPex customization ove...   0                    [OK]

下载image

$ docker pull ubuntu

下载指定版本的image

$ docker pull ubuntu:14:04