什么时docker?

Docker是通过内核虚拟化技术(namespaces及cgroups)来提供容器的资源隔离与资源限制。由于Docker通过操作系统层的虚拟化实现隔离(对操作系统的内核有要求,centos6已经没办法安装最新版docker,至少需要centos7的系统,如果需要最新docker特性,需要使用unbantu,因为redhalt内核比unbantu内核版本低),所以Docker容器在运行时,不需要类似虚拟机(VM)额外的操作系统开销,从而比kvm虚拟机更轻量。 docker是一种软件的打包技术。

docker理念

docker的主要目标是"Build,Ship and Run any App,Angwhere",构建,运输,处处运行 构建:制作docker镜像,打包容器的所有系统目录文件 运输:下载docker镜像 运行:基于docker镜像提供的rootfs,启动容器 总结:只要能运行docker容器,那么docker镜像中已经安装好的软件也可以运行,所以说docker是一种软件的打包技术,一次构建,出处运行。

docker的优点

1.解决了操作系统和软件运行环境的依赖

2.对于开发人员来说,再也不用担心不会部署开发环境 

3.开发环境,测试环境和生产环境高度一致。 

4.让用户体验产品新特性的又一种思路。

docker的安装

  1. 安装一台CentOS7(博主采用CentOS7.4)
    [root@docker01 /]# cat /etc/redhat-release
    CentOS Linux release 7.4.1708 (Core) 
  2. 修改主机名为docker01
    hostnamectl set-hostname docker01
  3. 配置yum源
    #删除本地源
    rm -fr  /etc/yum.repos.d/local.repo
    #下载阿里云源
    curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
    #下载docker源
    curl -o /etc/yum.repos.d/docker-ce.repo https://mirrors.ustc.edu.cn/docker-ce/linux/centos/docker-ce.repo
    
    #将源文件中的地址替换为清华源
    sed -i 's#download.docker.com#mirrors.tuna.tsinghua.edu.cn/docker-ce#g' /etc/yum.repos.d/docker-ce.repo 
    
  4. 安装docker
    yum install docker-ce -y
  5. 启动docker,并置为开机启动

    [root@docker01 /]# systemctl start docker.service
    [root@docker01 /]# systemctl enable docker.service
    Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.
    [root@docker01 /]# systemctl status docker.service
    ● docker.service - Docker Application Container Engine
       Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
       Active: active (running) since Mon 2019-07-22 10:34:27 CST; 21s ago
         Docs: https://docs.docker.com
     Main PID: 2602 (dockerd)
       CGroup: /system.slice/docker.service
               └─2602 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
    
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.023394018+08:00" level=info msg="pickfirstBalancer: HandleSubConnStateChange: 0xc4200452e0, REA...module=grpc
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.029328234+08:00" level=info msg="pickfirstBalancer: HandleSubConnStateChange: 0xc4200450b0, REA...module=grpc
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.043464741+08:00" level=info msg="Graph migration to content-addressability took 0.00 seconds"
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.044024276+08:00" level=info msg="Loading containers: start."
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.273802596+08:00" level=info msg="Default bridge (docker0) is assigned with an IP address 172.17...IP address"
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.334002476+08:00" level=info msg="Loading containers: done."
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.355108588+08:00" level=info msg="Docker daemon" commit=0dd43dd graphdriver(s)=overlay2 version=18.09.8
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.355245821+08:00" level=info msg="Daemon has completed initialization"
    Jul 22 10:34:27 docker01 dockerd[2602]: time="2019-07-22T10:34:27.399274108+08:00" level=info msg="API listen on /var/run/docker.sock"
    Jul 22 10:34:27 docker01 systemd[1]: Started Docker Application Container Engine.
    Hint: Some lines were ellipsized, use -l to show in full.

docker架构

启动docker: systemctl start docker

开机自启:systemctl enable docker

docker是一个cs架构: 通过docker version来查看

[root@docker01 /]# docker version
Client:
 Version:           18.09.8
 API version:       1.39
 Go version:        go1.10.8
 Git commit:        0dd43dd87f
 Built:             Wed Jul 17 17:40:31 2019
 OS/Arch:           linux/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          18.09.8
  API version:      1.39 (minimum version 1.12)
  Go version:       go1.10.8
  Git commit:       0dd43dd
  Built:            Wed Jul 17 17:10:42 2019
  OS/Arch:          linux/amd64
  Experimental:     false

docker最重要的三大组件: 镜像,容器,仓库

最后修改于 2019-07-22 11:27:16
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