Docker

Docker简介

一、简介

1、官方网站：https://www.docker.com/

2、简单介绍：

 Docker 是一个开源的应用容器引擎（基于go语言开发），让开发者可以打包他们的应用以及依赖包到一个可移植的容器中,然后发布到任何流行的Linux机器上,也可以实现虚拟化,容器是完全使用沙箱机制,相互之间不会有任何接口。

3、Docker安装

• 3.1、Centos安装：
   （1）Docker支持的CentOS版本：CentOS 6.5 (64-bit),要求系统内核版本为 2.6.32-431 或者以上
                CentOS 7 (64-bit)，要求系统的内核版本高于 3.10
    （2）查看系统版本
  
   （3) 查看内核版本
  
   （4）yum安装Docker

yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
yum makecache 
yum -y install docker-ce

• 3.2docker-compose安装
  （1） curl -L https://github.com/docker/compose/releases/download/1.17.1/docker-compose-uname -s-uname -m > /usr/local/bin/docker-compose
  （2）chmod +x /usr/local/bin/docker-compose

4、Docker三要素

• 4.1镜像（images）：其本质一个只读的模板，镜像可以用来创建Docker容器，一个镜像可以创建诸多容器。
• 4.2容器Container：基于镜像运行的实例
• 4.3仓库（Repository）：仓库是集中存放镜像文件的场所，分为公开仓库（Public）和私有仓库（Private），最大的公开仓库是官方提供的https://hub.docker.com，存放着官方构建的镜像，用户也可自己构建私有仓库。

二、Docker之Hello-World

1、Hello-World例子

（1）启动Docker

systemctl start docker

（2）从官方仓库拉取HelloWorld镜像

docker pull hello-world
Using default tag: latest
latest: Pulling from library/hello-world
1b930d010525: Pull complete 
Digest: sha256:6540fc08ee6e6b7b63468dc3317e3303aae178cb8a45ed3123180328bcc1d20f
Status: Downloaded newer image for hello-world:latest
[root@www ~]# docker run hello-world

（3）运行hello-world

docker run hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/get-started/

输出Hello from Docker! 这是Docker官方制作的一个Demo例子

三、镜像使用以及基本操作

1、从仓库拉取镜像，name代表镜像名字，tag代表镜像版本，不写默认拉取最新

docker pull name:tag

2、列出本地所有镜像

[root@openstack ~]# docker images
REPOSITORY                   TAG                 IMAGE ID            CREATED             SIZE
192.168.220.3:5000/member2   latest              e63d1e552172        3 weeks ago         506MB
centos-nginx                 latest              d6095daea42e        3 weeks ago         626MB
luoyuan323/cent-nginx        1.0                 d6095daea42e        3 weeks ago         626MB
cent-nginx                   latest              de0c63ea1f5d        3 weeks ago         626MB
cmd                          latest              5e21f03ced39        3 weeks ago         202MB
cent-ng                      v1                  72e8f1d0353b        3 weeks ago         314MB
centos                       latest              9f38484d220f        4 months ago        202MB
192.168.220.3:5000/reg       1.0                 f32a97de94e1        5 months ago        25.8MB
registry                     latest              f32a97de94e1        5 months ago        25.8MB
luoyuan323/luoyuan           2.0                 f32a97de94e1        5 months ago        25.8MB
luoyuan323/reg               3.0                 f32a97de94e1        5 months ago        25.8MB
nginx                        1.13                ae513a47849c        15 months ago       109MB

• REPOSITORY：表示镜像的仓库源

• TAG：镜像的版本

• IMAGE ID：镜像ID

• CREATED：镜像创建时间

• SIZE：镜像大小

3.运行一个镜像，name为镜像名字

docker run name

 其中run后面可以跟很多参数

4、删除镜像

docker rmi name/id

四、容器

1、容器是基于镜像运行的实例

2、查看所有容器

[root@openstack ~]# docker ps -a
CONTAINER ID        IMAGE                        COMMAND                  CREATED             STATUS                     PORTS                    NAMES
543084dcd379        192.168.220.3:5000/member2   "java -jar /web.jar"     2 weeks ago         Exited (143) 2 weeks ago                            mem
45b9332a4217        registry                     "/entrypoint.sh /etc…"   2 weeks ago         Up 2 weeks                 0.0.0.0:5000->5000/tcp   reg
11690df43cf4        192.168.220.3:5000/member2   "java -jar /web.jar"     3 weeks ago         Up 2 weeks                 8090/tcp                 compose_member-2_1
5b68e7525537        192.168.220.3:5000/member2   "java -jar /web.jar"     3 weeks ago         Up 2 weeks                 8090/tcp                 compose_member-1_1
ce3497370f61        nginx:1.13                   "nginx -g 'daemon of…"   3 weeks ago         Up 2 weeks                 0.0.0.0:80->80/tcp       member-nginx
43ab7cebdeaf        cmd                          "/bin/bash -c 'echo …"   3 weeks ago         Exited (0) 3 weeks ago                              inspiring_robinson
5009f3ced8f4        cmd                          "/bin/bash -c 'echo …"   3 weeks ago         Exited (0) 3 weeks ago                              dazzling_mcclintock
f5ad8d19741d        cmd                          "/bin/bash -c 'echo …"   3 weeks ago         Exited (0) 3 weeks ago                              blissful_ganguly
38e78ea2a1fb        cent-ng:v1                   "/bin/bash"              3 weeks ago         Exited (255) 2 weeks ago                            ng
af023cf90997        centos                       "/bin/bash"              3 weeks ago         Exited (255) 2 weeks ago                            cent3
a91696b17abf        centos                       "/bin/bash"              3 weeks ago         Exited (137) 3 weeks ago                            ce
a2ad495b9e58        centos                       "/bin/bash"              3 weeks ago         Exited (137) 3 weeks ago                            cent

3、查看运行中的容器

[root@openstack ~]# docker ps 
CONTAINER ID        IMAGE                        COMMAND                  CREATED             STATUS              PORTS                    NAMES
45b9332a4217        registry                     "/entrypoint.sh /etc…"   2 weeks ago         Up 2 weeks          0.0.0.0:5000->5000/tcp   reg
11690df43cf4        192.168.220.3:5000/member2   "java -jar /web.jar"     3 weeks ago         Up 2 weeks          8090/tcp                 compose_member-2_1
5b68e7525537        192.168.220.3:5000/member2   "java -jar /web.jar"     3 weeks ago         Up 2 weeks          8090/tcp                 compose_member-1_1
ce3497370f61        nginx:1.13                   "nginx -g 'daemon of…"   3 weeks ago         Up 2 weeks          0.0.0.0:80->80/tcp       member-nginx

4、删除容器(运行中的容器不能删除，删除会报错，到时可以强制删除docker rm -f name/id)

docker  rm  name/id

5、进入已经运行的容器

docker exec -it name/id bash