一、Docker 简介
lxc linux container,openvz
容器中各虚拟机只有一个内核,而是多个用户空间
在库中完成虚拟化,比如wine 或者在windows中运行bash
在应用程序的运行级别提供虚拟化,比如jvm
pstree , pid 为1 的进程 这个进程是直接和内核来打交道的
容器之间,和虚拟机之间隔离的技术
容器之间的隔离相对比较困难
NameSpace,(名称空间)
内核级别,环境隔离
PID NameSpace: 用于隔离pid号的 Linux 2.6.24 PID隔离;
Network NameSpace : Linux 2.6.29 网络名称空间的隔离 网络设备、网络栈、端口等网络设备隔离;
User NameSpace: Linux 用户空间的隔离 Linux 3.8 甚至 3.10之后 用户和用户组资源隔离;
IPC NameSpace: 进程间通信技术 Linux 2.6.19 signal 信号量、消息队列和共享内存的隔离;
UTS NameSpace: Linux 2.6.19 , 主机名和域名的隔离;
Mount NameSpace: Linux 2.4.19 挂载点(文件系统 )隔离;
API:clone()实现线程系统调用,用来创建新线程;
setns()设定一个新的属性,将某(进程|或设备)加入到新的NameSpace中去的;
unshare()非共享机制,脱离NameSpace,而关联至新NameSpace;
将NameSpace隔离开来没有问题,而问题在于,恶意用户强行调用资源,一个用户完全可以将系统资源耗尽,cpu占用至100%;
因此带来了另一种机制的出现;
CGroup: Linux Control Group,控制组 Linux 2.6.24被收入进内核
内核级别,限制、控制与一个进程组群的资源;
资源:CPU,内存,IO 级别来进行定义
google工程师:2006开始此技术,命令为进程容器而后命令为CGroup
功能:
Resource limitation:资源限制;
Prioritization:优先级控制;
Accounting:审计和统计,主要为计费;
Contorl:挂起进程,恢复进程;
CGroup 基于单根倒树状结构来实现
在CentOS7 中可以用mount 命令来查看其资源组的隔离技术已经被使用
/sys/fs/cgroup
mount
lssubsys -m
CGroup的子系统:
blkio:设定块设备的IO限制,而设定的子系统;
cpu:设定CPU的限制;
cpuacct:报告cgroup中所使用的CPU资源;
cpuset:为cgroup中的任务分配 CPU和内存资源 ;
memory:设定内存的使用限制;
devices:控制cgroup中的任务对设备的访问能务;
freezer: 挂起和恢复cgroup中的任务;
net_cls:(classid) ,使用等级级别标识符来标记网络数据包;
tc: 流量整形命令 ;
perf_event:对用户空间中任务,对用户空间产生的进程进行分类;
使用后使cgrup中的任务可以进行统一的性能测试;
hugetlb:转换后元缓冲区,对HugeTLB子系统进行限制;
CGroup中的术语:
task(任务):进程或线程;
cgroup:一个独立的资源控制单位,可以包含一个或多个子系统;
subsystem:子系统,
hierarchy:层级
AUFS:UnionFS:
UnionFS:把不同的物理位置的目录合并到同一个目录中。
Another UFS,Alternative UFS,Adanced UFS 几乎完全重写了unix FS
命令 #tc # lssubsys -m
Device mapper:
linux 2.6内核引入的最重要的技术之一,用于在内核中支持逻辑卷管理的通用设备映射技术;
Mapped Device
Mapping Table
Target Device
在内核空间只能开启一个端,但是可以映射至其它的用户空间
Device mapper:
Linux2.6 内核引入的最重要的技术之一,用于在内核 中支持逻辑卷管理的通用设备映射机制;
Mapped Device
Mapping Table
Target Device
Docker
2013,GO,Apache 2.0,dotCloud
C/S:
Docker Client:发起docker相关的请求
Docker Server:窗口运行的节点;
Containers 容器
images docker映像文件 –> 存于仓库之中
启动docker容器需要加载镜像文件 –> docker仓库上的镜像加载进来
docker允许我们创建私有仓库
比较难的,如何创建映像文件
dockerfile:
namespace cgroup
解决方案
lxc,openvz
lxc,linux container
libcontainer
Host OS –> hypervisor –> Guest OS
Host OS –> hpervisor –> user space(n个)
核心组件:
docker client:docker的客户端工具,是用户使用docker的主要接口,docker client 与docker daemon通信并将结果返回给用户
docker deamon:运行于宿主机上,Docker守护进程 ,用户可通过docker client其交互
image:镜像文件是只读的;用来创建container,一个镜像可以运行多个container;镜像文件可以通过Dockerfile文件来创建,可以从docker hub/registry下载;
repository
公共仓库:Docker hub/registry
私有仓库:docker registry
仓库可以存有:nginx image httpd image tomcat image
docker container: docker的运行实例,容器是一个隔离环境;
另外两个重要组件:
docker link: 各docker容器这间能够通信
docker volume:
二、Docker YUM源的安装配置
安装使用docker 通过使用epel源来实现, CentOS7 自带的就有了
dockerfile 自定义的docker 源 [root@node1 ~]# vim /etc/yum.repos.d/docker.repo [dockerrepo] name=Docker Repository baseurl=https://yum.dockerproject.org/repo/main/centos/$releasever/ gpgcheck=1 gpgkey=https://yum.dockerproject.org/gpg [jin] name=renjin2 baseurl=https://mirrors.aliyun.com/centos/7/os/x86_64/ gpgcheck=0 enabled=1 [extra] name=renjin3 baseurl=https://mirrors.aliyun.com/centos/7/extras/x86_64/ gpgcheck=0 enabled=1 [epel] name=renji4 baseurl=https://mirrors.aliyun.com/epel/7Server/x86_64/ gpgcheck=0 enabled=1
或者可以使用自带的源 https://mirrors.aliyun.com/centos/7.2.1511/extras/x86_64
查看docker版本的详细信息
[root@node1 ~]# yum info docker-engine Loaded plugins: fastestmirror, langpacks Loading mirror speeds from cached hostfile Installed Packages Name : docker-engine Arch : x86_64 Version : 17.04.0.ce Release : 1.el7.centos Size : 63 M Repo : installed From repo : dockerrepo Summary : The open-source application container engine URL : https://dockerproject.org License : ASL 2.0 Description : Docker is an open source project to build, ship and run any application as a : lightweight container. : : Docker containers are both hardware-agnostic and platform-agnostic. This means : they can run anywhere, from your laptop to the largest EC2 compute instance and : everything in between - and they don't require you to use a particular : language, framework or packaging system. That makes them great building blocks : for deploying and scaling web apps, databases, and backend services without : depending on a particular stack or provider. [root@node1 ~]# yum -y install docker-engine [root@node1 ~]# systemctl start docker.service
三、Dcoker 的简单测试及使用
[root@node1 ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE [root@node1 ~]# docker search centos NAME DESCRIPTION STARS OFFICIAL AUTOMATED centos The official build of CentOS. 3239 [OK] jdeathe/centos-ssh CentOS-6 6.8 x86_64 / CentOS-7 7.3.1611 x8... 63 [OK] jdeathe/centos-ssh-apache-php CentOS-6 6.8 x86_64 - Apache / PHP-FPM / P... 25 [OK] consol/centos-xfce-vnc Centos container with "headless" VNC sessi... 24 [OK] nimmis/java-centos This is docker images of CentOS 7 with dif... 24 [OK] gluster/gluster-centos Official GlusterFS Image [ CentOS-7 + Glu... 18 [OK] million12/centos-supervisor Base CentOS-7 with supervisord launcher, h... 15 [OK] torusware/speedus-centos Always updated official CentOS docker imag... 8 [OK] egyptianbman/docker-centos-nginx-php A simple and highly configurable docker co... 6 [OK] nathonfowlie/centos-jre Latest CentOS image with the JRE pre-insta... 5 [OK] centos/mariadb55-centos7 4 [OK] centos/redis Redis built for CentOS 2 [OK] harisekhon/centos-java Java on CentOS (OpenJDK, tags jre/jdk7-8) 2 [OK] harisekhon/centos-scala Scala + CentOS (OpenJDK tags 2.10-jre7 - 2... 2 [OK] blacklabelops/centos CentOS Base Image! Built and Updates Daily! 1 [OK] darksheer/centos Base Centos Image -- Updated hourly 1 [OK] freenas/centos Simple CentOS Linux interactive container 1 [OK] timhughes/centos Centos with systemd installed and running 1 [OK] januswel/centos yum update-ed CentOS image 0 [OK] kz8s/centos Official CentOS plus epel-release 0 [OK] grayzone/centos auto build for centos. 0 [OK] repositoryjp/centos Docker Image for CentOS. 0 [OK] otagoweb/centos Apache (with PHP7), built on CentOS 7 0 [OK] vcatechnology/centos A CentOS Image which is updated daily 0 [OK] grossws/centos CentOS 6 and 7 base images with gosu and l... 0 [OK] 之所以能搜索出来,是因为别人给我们做了公开的使用 [root@node1 ~]# docker search busybox NAME DESCRIPTION STARS OFFICIAL AUTOMATED busybox Busybox base image. 973 [OK] progrium/busybox 65 [OK] radial/busyboxplus Full-chain, Internet enabled, busybox made... 12 [OK] container4armhf/armhf-busybox Automated build of Busybox for armhf devic... 6 [OK] odise/busybox-python 4 [OK] multiarch/busybox multiarch ports of ubuntu-debootstrap 2 [OK] azukiapp/busybox This image is meant to be used as the base... 2 [OK] ofayau/busybox-jvm Prepare busybox to install a 32 bits JVM. 2 [OK] zanner/busybox https://github.com/sergej-kucharev/zanner-... 1 [OK] ofayau/busybox-libc32 Busybox with 32 bits (and 64 bits) libs 1 [OK] elektritter/busybox-teamspeak Leightweight teamspeak3 container based on... 1 [OK] getblank/busybox Docker container busybox for Blank 1 [OK] prom/busybox Prometheus Busybox Docker base images 1 [OK] skomma/busybox-data Docker image suitable for data volume cont... 1 [OK] odise/busybox-curl 1 [OK] jahroots/busybox Busybox containers 0 [OK] ggtools/busybox-ubuntu Busybox ubuntu version with extra goodies 0 [OK] cucy/busybox aouto build busybox 0 [OK] freenas/busybox Simple Busybox interactive Linux container 0 [OK] sdurrheimer/prom-busybox Moved to https://hub.docker.com/r/prom/bus... 0 [OK] jiangshouzhuang/busybox busybox 0 [OK] padcom/busybox-java Oracle Java on BusyBox 0 [OK] futurenda/busybox Mini busybox 0 [OK] hongtao12310/busybox for busybox image based on the gcr.io/goog... 0 [OK] ddn0/busybox fork of official busybox 0 [OK] [root@node1 ~]# docker pull buxybox [root@node1 ~]# docker pull busybox Using default tag: latest latest: Pulling from library/busybox 7520415ce762: Pull complete Digest: sha256:32f093055929dbc23dec4d03e09dfe971f5973a9ca5cf059cbfb644c206aa83f 校验码 Status: Downloaded newer image for busybox:latest
[root@node1 ~]# docker pull hub.magedu.com:5000/busybox ##指定到哪台服务器上获取busybox [root@node1 ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE busybox latest 00f017a8c2a6 3 weeks ago 1.11MB [root@node1 ~]# docker run -it busybox:latest /bin/sh ##启动一台虚拟机的实例 / # ls bin dev etc home proc root sys tmp usr var [root@node1 ~]# docker ps ##查看正在运行的主机 CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 7090d8fd9861 busybox:latest "/bin/sh" 2 minutes ago Up 2 minutes boring_archimedes
四、 docker的常用命令总结
环境信息相关: info version [root@node1 ~]# docker info ##查看docker的环境信息 [root@node1 ~]# docker version ##查看docker的版本号
系统维护相关:
images
inspect
build 创建映像文件
commint 基于运行中的容器创建映像文件
pause/unpause
ps
rm
rmi
run
start/stop/restart
top
kill
…
日志信息相关:
events
history
logs
Docer hub服务相关
login
logout
pull
push
search
基本操作:
获取映像:pull 启动容器:run [root@node1 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 7090d8fd9861 busybox:latest "/bin/sh" 17 minutes ago Up 17 minutes boring_archimedes [root@node1 ~]# docker kill 7090d8fd9861 7090d8fd9861 [root@node1 ~]# docker ps #结束一个docker进程 CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES [root@node1 ~]# docker ps -a #但不会删除容器 CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 7090d8fd9861 busybox:latest "/bin/sh" 20 minutes ago Exited (137) 3 minutes ago boring_archimedes [root@node1 ~]# docker rm 7090d8fd9861 #此时会删除container 7090d8fd9861 [root@node1 ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES [root@node1 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 2bca1aa3d38d busybox:latest "/bin/sh" 4 minutes ago Up 4 minutes naughty_goldberg [root@node1 ~]# docker docker docker-containerd-ctr dockerd docker-proxy docker-containerd docker-containerd-shim docker-init docker-runc [root@node1 ~]# docker commit 2bca1aa3d38d centos:newuser sha256:08d1d05a6e490c31b0e4e3ffb9532a25bb3d9e8f588b30990338f1ae64b34286 [root@node1 ~]# docker docker docker-containerd-ctr dockerd docker-proxy docker-containerd docker-containerd-shim docker-init docker-runc [root@node1 ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos newuser 08d1d05a6e49 9 seconds ago 1.11MB busybox latest 00f017a8c2a6 3 weeks ago 1.11MB [root@node1 ~]# docker run -it --rm centos:newuser /bin/sh / # [root@node1 ~]# docker kill fee1da85d418 fee1da85d418 [root@node1 ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
linux Kernel --> libcontainer --> (execdriver、networkdriver)--> Docker Daemon (GraphDB) --> API server --> 用户
在docker 之外有个重要存储还需要GraphDB GraphDB也称为图式数据库
Docker应用:
镜像:包含了启动Docker容器所需要的文件系统层给及其内容;
基于UninFS采用分层结构实现;
bootfs,rootfs
registry:用于保存镜像的元数据,保存docker镜像层次结构和元数据;
reposistory:由具有某个功能的镜像的所有相关版本构建成的集合;
index:管理用户的账号、访问权限、镜像及镜像标签等等相关的;
graph:从registry中下载的Docker镜像需要保存在本地,此功能即由graph完成;
/var/lib/docker/graph;
与镜像相关的命令:
docker images 列出本地的镜像
docker search 搜索
docker pull 下载镜像
docker push 上传镜像
docker login 登录
docker logout 登出
创建镜像:commint,build
删除本地镜像: rmi
容器:也可以想象成一个虚拟机
独立运行的一个或一组应用,以及它们运行的环境
命令:
run,kill,stop,start,restart ,log,export,import
启动方法:
通过镜像创建一个新的容器: run
启动一个处于停止状态的容器: start
容器本来就是应用的,当应用结束时,程序也会结束的;
[root@node1 ~]# docker run busybox:latest /bin/echo "hello world" hello world [root@node1 ~]# docker run -it --name=busybox busybox:latest /bin/sh [root@node1 ~]# docker stop busybox ##正常停止一个容器,相当于正常关机
busybox
run命令:
–name= Assign a name to the container
-i,–interactive=false Keep STDIN open even if not attached
it,-tty=false Alocate a pseudo-TTY
–net=default Set the Network for the container
步骤:
检查本地是否存在指定的镜像,不存在则从registry下载;
利用镜像启动容器
分配一个文件系统,并且在只读的镜像层之外,挂载一个可读写层;
从宿主机配置的网桥口中,桥接一个虚拟接口给此容器;
从地址池中分配一个地址容器;
执行用户指定的应用程序;
程序执行完成后,容器即终止;
logs命令:获取一个容器的日志,获取其输出信息;
对于交互式模式启动的容器,终止可以使用exit 命令或ctrl+d组合键;
attach 附加至一个运行中的容器;
[root@node1 ~]# docker start 31a67d66b2c2 [root@node1 ~]# docker attach busybox [root@node1 ~]# docker run busybox:latest /bin/echo "hello world" [root@node1 ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES d35a2673722e busybox:latest "/bin/echo 'hello ..." 13 seconds ago Exited (0) 12 seconds [root@node1 ~]# docker start d35a2673722e d35a2673722e [root@node1 ~]# docker logs cabd0e52f8f8 ##可以查看执行命令后的输出信息 hello world hello world hello world / # exit 终止当前容器 或者ctrl +d attach [root@node1 ~]# docker start -i busybox ##启动一个交互式一个接口 [root@node1 ~]# docker start busybox [root@node1 ~]# docker attach busybox ##附加至一个运行中的容器; / #
Docker Hub:
registry有两种;
docker hub:
private registry
# docker login
# docker push busybox:latest
[root@node2 yum.repos.d]# yum -y install docker-registry 上条命令实质上安装的是另外的一个包 [root@node2 yum.repos.d]# yum -y installdocker-distribution-2.6.0-1.el7.x86_64 [root@node1 yum.repos.d]# systemctl start docker-distribution.service [root@node1 yum.repos.d]# ss -tnl | grep 5000 LISTEN 0 128 :::5000 :::* [root@node1 yum.repos.d]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos newuser 08d1d05a6e49 2 weeks ago 1.11MB centos latest 98d35105a391 5 weeks ago 192MB busybox latest 00f017a8c2a6 6 weeks ago 1.11MB [root@node1 yum.repos.d]# [root@node1 yum.repos.d]# docker tag 08d1d05a6e49 192.168.99.15:5000/centos:1.2.1 给一个镜像打标签 [root@node1 yum.repos.d]# docker push 192.168.99.15:5000/centos:1.2.1
原创文章,作者:kang,如若转载,请注明出处:http://www.178linux.com/79168