一、docker介绍:
docker是一种容器，什么是容器：
A container is a standard unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another. A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings.
容器和虚拟机的区别：
Containers and virtual machines have similar resource isolation and allocation benefits, but function differently because containers virtualize the operating system instead of hardware. Containers are more portable and efficient.
Reference：https://www.docker.com/resources/what-container
镜像，容器，仓库是docker中经常出现的三个对象。
镜像：类似于.ios文件
容器：类似于已经安装在硬件上的操作系统
仓库：类似于集中存放.ios文件的地方，可以在本地，也可以在网上。
二、docker安装：
对于使用 systemd 的系统，请在 /etc/docker/daemon.json 中写入如下内容（如果文件不存在请新建该文件）：
{"registry-mirrors":["https://registry.docker-cn.com"]}之后重新启动服务：
$ sudo systemctl daemon-reload
$ sudo systemctl restart docker
docker安装
[root@192 ~]# yum install -y docker
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
base | 3.6 kB 00:00
extras | 2.9 kB 00:00
updates | 2.9 kB 00:00
updates/7/x86_64/primary_d 31% [====- ] 1.2 MB/s | 2.3 MB 00:04
三、镜像使用
查询镜像
#docker search
[root@192 ~]# docker search centos
INDEX NAME DESCRIPTION STARS OFFICIAL AUTOMATED
docker.io docker.io/centos The official build of CentOS. 5890 [OK]
docker.io docker.io/ansible/centos7-ansible Ansible on Centos7 128 [OK]
docker.io docker.io/jdeathe/centos-ssh OpenSSH / Supervisor / EPEL/IUS/SCL Repos ... 114 [OK]
docker.io docker.io/consol/centos-xfce-vnc Centos container with "headless" VNC sessi... 111 [OK]获取镜像
#docker pull centos
Using default tag: latest
Trying to pull repository docker.io/library/centos ...
latest: Pulling from docker.io/library/centos
8a29a15cefae: Pull complete
Digest: sha256:fe8d824220415eed5477b63addf40fb06c3b049404242b31982106ac204f6700
Status: Downloaded newer image for docker.io/centos:latest
[root@192 ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/centos latest 470671670cac 2 months ago 237 MB创建容器
[root@192 ~]# docker run -t -i centos:latest /bin/bash
[root@07bc957293e7 /]# exit
exit导出容器
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
07bc957293e7 centos "/bin/bash" 13 minutes ago Up 4 minutes ecstatic_curie
[root@192 ~]# docker export ecstatic_curie -o centos.tar
[root@192 ~]# ll
total 239300
-rw-------. 1 root root 1405 Mar 17 15:38 anaconda-ks.cfg
-rw-------. 1 root root 245035008 Mar 20 14:50 centos.tar
-rwxr-xr-x. 1 root root 169 Mar 20 13:30 docker_in.sh将导出的容器导入为镜像
[root@192 ~]# docker import - centos:load < centos.tar
sha256:74393833eb5496ae02d5d363515fd94c1026dd7d041870cf2521d63db3229170
[root@192 ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
centos load 74393833eb54 16 seconds ago 237 MB
docker.io/centos latest 470671670cac 2 months ago 237 MB
[root@192 ~]#进入正在运行的docker
docker attach 退出容器终端，会导致容器的停止
Usage: docker attach [OPTIONS] CONTAINER
Attach to a running container
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
07bc957293e7 centos "/bin/bash" 4 minutes ago Exited (0) 43 seconds ago ecstatic_curie
[root@192 ~]# docker start ecstatic_curie
ecstatic_curie
[root@192 ~]# docker attach ecstatic_curie
[root@07bc957293e7 /]# exit
exit
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
07bc957293e7 centos "/bin/bash" 5 minutes ago Exited (0) 9 seconds ago ecstatic_curiedocker exec 退出容器终端，不会导致容器的停止
Usage: docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
Run a command in a running container
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
07bc957293e7 centos "/bin/bash" 5 minutes ago Exited (0) 9 seconds ago ecstatic_curie
[root@192 ~]# docker start ecstatic_curie
ecstatic_curie
[root@192 ~]# docker exec -it ecstatic_curie /bin/bash
[root@07bc957293e7 /]# exit
exit
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
07bc957293e7 centos "/bin/bash" 9 minutes ago Up 43 seconds ecstatic_curie编写脚本，使容器在输入exit命令时，仍可以运行
[root@192 ~]# vim login.sh
#!/bin/bash
login(){
docker exec -it $1 /bin/bash
}
login $1授予运行权限
[root@192 ~]# chmod +x docker_in.sh运行容器
[root@192 ~]# ./login.sh blissful_euler
[root@ed414d4603bf /]# exit
logout
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ed414d4603bf centos "/bin/bash" 54 minutes ago Up 2 minutes blissful_euler
30fba2607523 centos:latest "/bin/bash" 2 hours ago Exited (127) 2 hours ago pensive_lovelace四、网络管理
随机端口映射
[root@192 ~]# docker run -d -P nginx
42c48cf7ffc6d1449cc20278a7ce5a2366e0703473214b368fe6cc7ed8f7a144
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
42c48cf7ffc6 nginx "nginx -g 'daemon ..." 8 seconds ago Up 7 seconds 0.0.0.0:32768->80/tcp keen_clarke访问验证
指定端口映射
[root@192 ~]# docker run -d -p 192.168.75.131:11111:80 --name test nginx
2514bd29d8868108d990f0046110f83bd0b7d2cadfc43b54c824d63f5c7bb850
[root@192 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2514bd29d886 nginx "nginx -g 'daemon ..." 5 seconds ago Up 5 seconds 192.168.75.131:11111->80/tcp test
42c48cf7ffc6 nginx "nginx -g 'daemon ..." 14 minutes ago Up 14 minutes 0.0.0.0:32768->80/tcp keen_clarke
07bc957293e7 centos "/bin/bash" About an hour ago Up About an hour ecstatic_curie访问验证
五、数据管理
自动生成挂载目录
[root@192 ~]# docker run -d --name=data-test -v /data nginx
[root@192 ~]# ./login.sh data-test
root@626f0474ea4c:/# cd /data/
root@626f0474ea4c:/data# ls
root@626f0474ea4c:/data# touch hello
root@626f0474ea4c:/data# ls
hello
root@626f0474ea4c:/data# exit
exit
[root@192 ~]# cd /var/lib/docker/volumes/
b0eed69ea8428a1cbe6868ccc7625903619d0a33df4d975e5ecfdd2f443d0922/ metadata.db
[root@192 ~]# cd /var/lib/docker/volumes/b0eed69ea8428a1cbe6868ccc7625903619d0a33df4d975e5ecfdd2f443d0922/_data/
[root@192 _data]# ls
hello指定目录挂载卷
--volumes-from list Mount volumes from the specified container
[root@192 ~]# docker run -it --name data-test3 --volumes-from data-test2 centos /bin/bash
[root@7628ca6d4af5 /]# ls /data/
hello
[root@7628ca6d4af5 /]#六、制作镜像
分层制作镜像，以适应不同的需求
系统镜像：基本的操作系统
运行环境镜像：安装有应用运行需要的环境
加载应用的镜像：将应用加载到运行环境镜像中
镜像的制作大致有两种方法，手工制作和Dockerfile自动制作
手动制作流程
由镜像创建容器-->进入容器配置环境并安装应用-->docker export导出-->docker import导入
由Dockerfile制作
制作系统镜像
[root@192 OS]# vim Dockerfile
#base image
FROM centos
#change yum
RUN rm -f /etc/yum.repos.d/*.repo
RUN curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo
RUN yum clean all
RUN yum makecache
RUN yum -y install vim有一点要注意的就是要看清楚自己FROM的centos镜像是哪个版本，我一开始就以为和我宿主机一样都是centos7，结果出错的时候才发现是8。
[root@192 OS]# docker build -t test/centos:test ./
Sending build context to Docker daemon 2.048 kB
Step 1/6 : FROM centos
---> 470671670cac
Step 2/6 : RUN rm -f /etc/yum.repos.d/*.repo
---> Running in 869ae4c5e53e
---> 528828074a97
Removing intermediate container 869ae4c5e53e
.............
Complete!
---> 970976fcc1ad
Removing intermediate container d81031b28239
Successfully built 970976fcc1ad
[root@192 OS]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
test/centos test 970976fcc1ad About a minute ago 313 MB
docker.io/nginx latest 6678c7c2e56c 2 weeks ago 127 MB
docker.io/centos latest 470671670cac 2 months ago 237 MB我后来对比了下yum换源前后的下载速度，发下差别并不大，不知道是我无线网的原因还是什么，官方yum源感觉并不比阿里云慢多少。
制作运行环境镜像
[root@192 OS]# cd ../runtime/
[root@192 runtime]# vim Dockerfile
#Dockerfile
FROM centos:base
RUN yum -y install nginx
[root@192 runtime]# docker build -t test/centos:nginx ./
Sending build context to Docker daemon 2.048 kB
Step 1/2 : FROM test/centos:test
---> 970976fcc1ad
Step 2/2 : RUN yum -y install nginx
---> Running in 277c2ba57075
Last metadata expiration check: 0:02:58 ago on Fri Mar 20 12:52:14 2020.
Dependencies resolved.
================================================================================
Package Arch Version Repo Size
================================================================================
Installing:
nginx x86_64 1:1.14.1-9.module_el8.0.0+184+e34fea82
..............................
Complete!
---> 72acef2a3771
Removing intermediate container 277c2ba57075
Successfully built 72acef2a3771
[root@192 runtime]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
test/centos nginx 72acef2a3771 5 minutes ago 383 MB
test/centos test 970976fcc1ad 8 minutes ago 313 MB
docker.io/nginx latest 6678c7c2e56c 2 weeks ago 127 MB
docker.io/centos latest 470671670cac 2 months ago 237 MB
[root@192 runtime]#将应用迁移到运行环境镜像
[root@192 runtime]# cd ../application/
[root@192 application]# mkdir app
[root@192 application]# vim Dockerfile
[root@192 application]# cat Dockerfile
FROM test/centos:nginx
COPY ./app /myapp
[root@192 application]# docker build -t test/centos:app ./
Sending build context to Docker daemon 2.56 kB
Step 1/2 : FROM test/centos:nginx
---> 72acef2a3771
Step 2/2 : COPY ./app /myapp
---> da5f26ad6449
Removing intermediate container ec422e10c133
Successfully built da5f26ad6449
[root@192 ~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
test/centos app da5f26ad6449 9 minutes ago 383 MB
test/centos nginx 72acef2a3771 19 minutes ago 383 MB
test/centos test 970976fcc1ad 22 minutes ago 313 MB
docker.io/nginx latest 6678c7c2e56c 2 weeks ago 127 MB
docker.io/centos latest 470671670cac 2 months ago 237 MB
[root@192 ~]#
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