Docker学习1 - CentOS7安装docker

最近学习docker, 想着之前一致没有太多的毅力写blog，最近准备好好的写blog，记录下自己技术成长的点滴

话不多说, pratice is everything,先安装环境再说

由于对centos系列比较熟悉，于是选择在centos7上安装, 大家可以根绝自己熟悉的平台安装。过程都大同小异,就是windows和mac需要使用boot2docker安装，稍显麻烦

安装前提条件

1. centos7

2. 内核3.8和以上

[root@centos7-docker ~]# uname -a
Linux centos7-docker 3.10.0-229.7.2.el7.x86_64 #1 SMP Tue Jun 23 22:06:11 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

显示是3.10，符合要求

3. 检查device mapper

Device mapper 是 Linux 2.6 内核中提供的一种从逻辑设备到物理设备的映射框架机制，在该机制下，用户可以很方便的根据自己的需要制定实现存储资源的管理策略，当前比较流行的 Linux 下的逻辑卷管理器如 LVM2（Linux Volume Manager 2 version)、EVMS(Enterprise Volume Management System)、dmraid(Device Mapper Raid Tool)等都是基于该机制实现的。理解该机制是进一步分析、理解这些卷管理器的实现及设计的基础

请参考这篇文章

http://www.ibm.com/developerworks/cn/linux/l-devmapper/

这里使用device mapper做为docker的存储驱动, 从centos6开始就自带了device mapper

检查是否支持device mapper

[root@centos7-docker ~]# ls -l /sys/class/misc/device-mapper
lrwxrwxrwx 1 root root 0 Jul 26 08:34 /sys/class/misc/device-mapper -> ../../devices/virtual/misc/device-mapper

或者

[root@centos7-docker ~]# grep device-mapper /proc/devices
253 device-mapper

如果没有检测到,使用yum安装，modprobe加载

[root@centos7-docker ~]# yum -y install device-manager

[root@centos7-docker ~]# modprobe md_mod

安装Docker

[root@centos7-docker ~]# yum -y install docker

启动Docker

[root@centos7-docker ~]# systemctl start docker
[root@centos7-docker ~]# systemctl enable docker
ln -s '/usr/lib/systemd/system/docker.service' '/etc/systemd/system/multi-user.target.wants/docker.service'
[root@centos7-docker ~]# systemctl status docker
docker.service - Docker Application Container Engine
   Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled)
   Active: active (running) since Sun 2015-07-26 09:31:55 CST; 17s ago
     Docs: http://docs.docker.com
 Main PID: 3217 (docker)
   CGroup: /system.slice/docker.service
           └─3217 /usr/bin/docker -d --selinux-enabled


Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=warning msg="Docker could not enable SELinux on the host system"
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="+job init_networkdriver()"
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="-job init_networkdriver() = OK (0)"
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="Loading containers: start."
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="Loading containers: done."
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="docker daemon: 1.6.2 ba1f6c3/1.6.2; execdriver: native-0.2; graphdriv...vicemapper"
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="+job acceptconnections()"
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="-job acceptconnections() = OK (0)"
Jul 26 09:31:55 centos7-docker docker[3217]: time="2015-07-26T09:31:55+08:00" level=info msg="Daemon has completed initialization"
Jul 26 09:31:55 centos7-docker systemd[1]: Started Docker Application Container Engine.
Hint: Some lines were ellipsized, use -l to show in full.

能够使用docker命令

[root@centos7-docker ~]# docker

[root@centos7-docker ~]# docker info
Containers: 0
Images: 0
Storage Driver: devicemapper
 Pool Name: docker-253:1-201487135-pool
 Pool Blocksize: 65.54 kB
 Backing Filesystem: xfs
 Data file: /dev/loop0
 Metadata file: /dev/loop1
 Data Space Used: 307.2 MB
 Data Space Total: 107.4 GB
 Data Space Available: 51.46 GB
 Metadata Space Used: 733.2 kB
 Metadata Space Total: 2.147 GB
 Metadata Space Available: 2.147 GB
 Udev Sync Supported: true
 Data loop file: /var/lib/docker/devicemapper/devicemapper/data
 Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
 Library Version: 1.02.93-RHEL7 (2015-01-28)
Execution Driver: native-0.2
Kernel Version: 3.10.0-229.7.2.el7.x86_64
Operating System: CentOS Linux 7 (Core)
CPUs: 4
Total Memory: 7.64 GiB
Name: centos7-docker
ID: E33R:GBHN:UOJF:JFSW:NBYI:ERJS:FSNS:KEPU:WDKO:P3DA:ZFBX:NGCT

到这里, docker就安装完毕