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阿里云ECS部署Docker

loongshawn 人气:3

1、前言

京东2016年618大促,全部应用系统和大部分的DB服务都跑在Docker上。据官方估计,本次大促活动中,京东线上将会启动近15万个Docker容器,从数量上来看,京东是全球范围内Docker的应用大户之一。

为什么docker被京东如此看重,这种微服务化治理到底有何魅力?

决定开始对docker进行下学习并尝试应用到日常业务中来。今天在阿里云ECS的centos上搭建了一个Docker,顺便将一些常用操作记录下,操作系统版本为CentOS6.5。

本文的主要内容介绍阿里云ECS如何安装docker,及docker基础命令详解,通过这篇文章,可以让docker新手开始熟悉和操作docker,慢慢入门。

2、内核支持

官方文档要求Linux kernel至少3.8以上,且docker只能运行在64位的系统中。由于RHEL6和CentOS6的内核版本为2.6,因此必须要先升级内核。

首先,查看阿里云ECS Linux服务器系统内核版本:

$uname -r
2.6.32-220.23.2.ali878.el6.x86_64

2.1、升级内核

由于当前内核版本较低,我们需要把系统内核升级到3.10版本,接下来为具体操作步骤:

(1). yum安装带aufs模块的3.10内核

[dddd@v069208183.sqa.zmf /home/dddd]
$cd /etc/yum.repos.d
$sudo wget http://www.hop5.in/yum/el6/hop5.repo
$sudo yum install kernel-ml-aufs kernel-ml-aufs-devel

(2). 下载内核

(3). 安装内核

(4). 安装成功

(5). 修改内核配置

修改grub的主配置文件/etc/grub.conf,设置default=0,表示第一个title下的内容为默认启动的kernel(一般新安装的内核在第一个位置)

[dddd@v069208183.sqa.zmf /etc/yum.repos.d]
$sudo vi /etc/grub.conf

(6). 重启系统

[dddd@v069208183.sqa.zmf /etc/yum.repos.d]
$sudo reboot

Broadcast message from dddd@v069208183.sqa.zmf
    (/dev/pts/1) at 18:32 ...

The system is going down for reboot NOW!

这时候你的内核就成功升级了

[dddd@v069208183.sqa.zmf /home/admin/
$uname -r
3.10.5-3.el6.x86_64

查看内核是否支持aufs:

[dddd@v069208183.sqa.zmf /home/admin/]
$grep aufs /proc/filesystems
nodev   aufs

3、Docker安装

3.1、关闭selinux

[dddd@v069208183.sqa.zmf /home/admin/]
$sudo setenforce 0
setenforce: SELinux is disabled

[dddd@v069208183.sqa.zmf /home/admin/]
$sudo sed -i '/^SELINUX=/c\SELINUX=disabled' /etc/selinux/config

3.2、安装epel

[dddd@v069208183.sqa.zmf /]
$sudo rpm -ivh http://mirrors.sohu.com/fedora-epel/6/x86_64/epel-release-6-8.noarch.rpm
Retrieving http://mirrors.sohu.com/fedora-epel/6/x86_64/epel-release-6-8.noarch.rpm
warning: /var/tmp/rpm-tmp.NNZYOY: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY
Preparing...                ########################################### [100%]
   1:epel-release           ########################################### [100%]

[dddd@v069208183.sqa.zmf /]
$sudo sed -i 's/^mirrorlist=https/mirrorlist=http/' /etc/yum.repos.d/epel.repo

3.3、yum安装docker-io

[dddd@v069208183.sqa.zmf /]
$sudo yum -y install docker-io

安装成功:

3.4、启动docker

启动的过程中有点小插曲,第一次启动失败。

[dddd@v069208183.sqa.zmf /]
$sudo service docker start
Starting cgconfig service:                                 [  OK  ]
Starting docker:                                       [  OK  ]

[dddd@v069208183.sqa.zmf /]
$docker version
Client version: 1.7.1
Client API version: 1.19
Go version (client): go1.4.2
Git commit (client): 786b29d/1.7.1
OS/Arch (client): linux/amd64
Get http:///var/run/docker.sock/v1.19/version: dial unix /var/run/docker.sock: permission denied. Are you trying to connect to a TLS-enabled daemon without TLS?

上面看似启动成功,其实是失败了,查看docker日志即可,docker日志地址为/var/log/docker:

$cat /var/log/docker
\nSat Jun 25 18:54:55 CST 2016\n
time="2016-06-25T18:54:56.013084200+08:00" level=info msg="Listening for HTTP on unix (/var/run/docker.sock)"
time="2016-06-25T18:54:56.206980482+08:00" level=warning msg="Running modprobe bridge nf_nat failed with message: insmod /lib/modules/3.10.5-3.el6.x86_64/kernel/net/llc/llc.ko \ninsmod /lib/modules/3.10.5-3.el6.x86_64/kernel/net/802/stp.ko \ninsmod /lib/modules/3.10.5-3.el6.x86_64/kernel/net/ipv6/ipv6.ko disable=1\ninsmod /lib/modules/3.10.5-3.el6.x86_64/kernel/net/bridge/bridge.ko \ninsmod /lib/modules/3.10.5-3.el6.x86_64/kernel/net/netfilter/nf_conntrack.ko \ninsmod /lib/modules/3.10.5-3.el6.x86_64/kernel/net/netfilter/nf_nat.ko \n, error: exit status 1"
time="2016-06-25T18:54:56.380986865+08:00" level=fatal msg="Error starting daemon: Error initializing network controller: Error creating default \"bridge\" network: can't find an address range for interface \"docker0\""

这个问题的来源就是因为docker弱智地为docker0接口选择了一个172.17.42.1的IP,而恰好ECS占用了172.16.0.0/255.240.0.0。

解决方法有两种:

上述两种方法均能过正常启动,本地均已测试通过,不过我还是觉得方法一好,直接把网段写入配置中,省的每次启动都要带上网段。

针对方法一进行如下说明,在/etc/default/docker文件中新增记录DOCKER_OPTS=”–bip=192.168.17.1/24”

[xiaolong.xiao@v069208183.sqa.zmf /var/log]
$sudo vi /etc/default/docker
Error detected while processing /root/.vimrc:
line   16:
E518: Unknown option: foldlevel=100
Press ENTER or type command to continue

有关docker0网桥的详细介绍参考:http://wiki.jikexueyuan.com/project/docker-technology-and-combat/docker0.html

3.5、查看docker版本

利用命令docker version

[dddd@v069208183.sqa.zmf /var/log]
$sudo docker version
Client version: 1.7.1
Client API version: 1.19
Go version (client): go1.4.2
Git commit (client): 786b29d/1.7.1
OS/Arch (client): linux/amd64
Server version: 1.7.1
Server API version: 1.19
Go version (server): go1.4.2
Git commit (server): 786b29d/1.7.1
OS/Arch (server): linux/amd64

3.6、开启启动docker

sudo chkconfig docker on

4、docker命令的使用

1、直接输入docker命令来查看所有的Options和Commands。

查看某一个command的详细使用方法:docker COMMAND –help

[dddd@v069208183.sqa.zmf /home/dddd]
$sudo docker pull -help
Warning: '-help' is deprecated, it will be replaced by '--help' soon. See usage.

Usage: docker pull [OPTIONS] NAME[:TAG|@DIGEST]

Pull an image or a repository from the registry

  -a, --all-tags=false    Download all tagged images in the repository
  --help=false            Print usage

2、搜索可用的docker镜像:docker search NAME

[dddd@v069208183.sqa.zmf /]
$sudo docker search centos
INFO[0104] GET /v1.19/images/search?term=centos
NAME                          DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
centos                        The official build of CentOS.                   2373      [OK]
ansible/centos7-ansible       Ansible on Centos7                              77                   [OK]
jdeathe/centos-ssh            CentOS-6 6.7 x86_64 / CentOS-7 7.2.1511 x8...   25                   [OK]
nimmis/java-centos            This is docker images of CentOS 7 with dif...   12                   [OK]
million12/centos-supervisor   Base CentOS-7 with supervisord launcher, h...   11                   [OK]
gluster/gluster-centos        Official GlusterFS Image [ CentOS7 +  Glus...   9                    [OK]
torusware/speedus-centos      Always updated official CentOS docker imag...   8                    [OK]
nickistre/centos-lamp         LAMP on centos setup                            4                    [OK]
centos/mariadb55-centos7                                                      3                    [OK]
nathonfowlie/centos-jre       Latest CentOS image with the JRE pre-insta...   3                    [OK]
consol/sakuli-centos-xfce     Sakuli end-2-end testing and monitoring co...   2                    [OK]
darksheer/centos              Base Centos Image -- Updated hourly             1                    [OK]
blacklabelops/centos          CentOS Base Image! Built and Updates Daily!     1                    [OK]
timhughes/centos              Centos with systemd installed and running       1                    [OK]
grossws/centos                CentOS 6 and 7 base images with gosu and l...   0                    [OK]
kz8s/centos                   Official CentOS plus epel-release               0                    [OK]
harisekhon/centos-scala       Scala + CentOS (OpenJDK tags 2.10-jre7 - 2...   0                    [OK]
jsmigel/centos-epel           Docker base image of CentOS w/ EPEL installed   0                    [OK]
labengine/centos              Centos image base                               0                    [OK]
ustclug/centos                 USTC centos                                    0                    [OK]
januswel/centos               yum update-ed CentOS image                      0                    [OK]
ericuni/centos                centos dev                                      0                    [OK]
grayzone/centos               auto build for centos.                          0                    [OK]
dmglab/centos                 CentOS with some extras - This is for the ...   0                    [OK]
repositoryjp/centos           Docker Image for CentOS.                        0                    [OK]

3、下载镜像:docker pull NAME[:TAG]

比如获取最新的centos镜像:docker pull centos:latest

注意:这里要写用docker search搜索到的完整的镜像名。

同时当前下载的是官方的镜像,下载速度会有点慢,centos镜像大约200M,下载耗时半小时。后面有时间将会实践如何搭建私有仓库。

[dddd@v069208183.sqa.zmf /home/dddd]
$sudo docker pull centos:latest
Pulling repository centos
2a332da70fd1: Download complete
3690474eb5b4: Download complete
b48a20c39b28: Download complete
c79ebe41b35a: Download complete
Status: Downloaded newer image for centos:latest

4、查看安装的镜像:docker images [NAME]

$sudo docker images centos
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
centos              latest              2a332da70fd1        3 weeks ago         196.8 MB

5、在docker容器中运行命令:docker run IMAGE [COMMAND] [ARG…]

docker run命令有两个参数,一个是镜像名,一个是要在镜像中运行的命令。

注意:IMAGE=REPOSITORY[:TAG],如果IMAGE参数不指定镜像的TAG,默认TAG为latest。

在刚刚下载的镜像中输出”loongshawn”:docker run centos echo ‘loongshawn’

[dddd@v069208183.sqa.zmf /home/dddd]
$sudo docker run centos echo "loongshawn"
loongshawn

6、列出容器:docker ps -a

查看最近生成的容器:docker ps -l
查看正在运行的容器:docker ps

7、显示容器的标准输出:docker logs CONTAINERID

无需拷贝完整的id,一般写最开始的三至四个字符即可。

8、在容器中安装新程序,比如安装ifconfig命令(centos7默认没有ifconfig)

运行镜像,执行ifconfig,找不到此命令。此时进入镜像执行yum install net-tools。

[dddd@v069208183.sqa.zmf /home/dddd]
$sudo docker run -i -t centos /bin/bash
[root@bed98ed5934a /]# ifconfig
bash: ifconfig: command not found
[root@bed98ed5934a /]#

给容器安装网络服务:

执行ifconfig命令:

9、保存对容器的修改并生成新的镜像:docker commit CONTAINERID [REPOSITORY[:TAG]]

REPOSITORY参数可以是新的镜像名字,也可以是旧的镜像名;如果和旧的镜像名和TAG都相同,会覆盖掉旧的镜像。

10、停止正在运行的容器:docker stop CONTAINERID

默认等待10秒钟再杀死指定容器。可以使用-t参数来设置等待时间。

11、查看容器或镜像的详细信息:docker inspect CONTAINERID|IMAGE

参数可以是容器的ID或者是镜像名(NAME:TAG)。

12、删除容器:docker rm CONTAINERID

查看所有容器ID:docker ps -a -q
删除所有的容器:docker rm $(docker ps -a -q)

13、删除镜像:docker rmi IMAGE

14.查看docker的信息,包括Containers和Images数目、kernel版本等。

5、创建容器并登入

1、创建一个新容器并登入:docker run -i -t IMAGE /bin/bash

使用image创建container并进入交互模式,login shell是/bin/bash,现在可以自由的对容器进行操作了。最后使用exit退出容器。
注意:如果IMAGE参数不指定TAG,默认TAG为latest。

$ sudo docker run -i -t centos /bin/bash

2、启动一个退出的容器:docker start CONTAINERID

[dddd@v069208183.sqa.zmf /home/dddd]
$sudo docker start 340943d115b6
340943d115b6

[dddd@v069208183.sqa.zmf /home/dddd]
$sudo docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
340943d115b6        centos              "sleep 100"         11 minutes ago      Up 6 seconds                            cocky_pare

3、attach到运行中的容器:docker attach CONTAINERID

6、参考资料

Docker官网教程
CentOS 安装 Docker
Docker入门教程

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