CoreOS部署及应用

简介 CoreOS是基于Chrome OS修改的极简化Linux发行版本（CoreOS只需要114MB的内存就能运行，启动时占用的内存比普通的Linux服务器要少40%。），顶层提供分布式数据存储和系统管理工具，能够扩展并管理庞大的云计算服务器设施，用其官网概括理念为“A new way to think about servers”、“CoreOS is Linux for massive s

木讷大叔爱运维

3852人浏览 · 2016-02-29 10:48:45

木讷大叔爱运维 · 2016-02-29 10:48:45 发布

简介

CoreOS是基于Chrome OS修改的极简化Linux发行版本（CoreOS只需要114MB的内存就能运行，启动时占用的内存比普通的Linux服务器要少40%。），顶层提供分布式数据存储和系统管理工具，能够扩展并管理庞大的云计算服务器设施，用其官网概括理念为“A new way to think about servers”、“CoreOS is Linux for massive server deployments”，表示一个新思维方式思考未来服务器大规模部署的Linux服务器操作系统。CoreOS中的所有应用都完全在Docker容器中运行，操作系统本身会定期自动更新。
CoreOS具有以下几点特性：
1. Linux内核，Linux运行所需存在两个ROOT分区，一个被用作启动分区，一个被用作更新分区更新分区在更新完成后，自动重新启动系统，当前机器不需要从负载集群中移除，为了保证其它应用程序不被打断，会通过Linux cgroup限制更新过程中的磁盘、网络等IO使用。
2. systemd，作为默认系统和服务管理器
3. root分区被设计成只读，用以保证数据的一致性和更新可用
4. CoreOS很明智使用Docker作为容器管理器用以构建、发布应用，从这个层面来看，一个应用其实就是一个容器。
5. etcd组件负责服务发现和配置共享，采用Raft分布式一致性协议算法，承担起，组件之间服务通信使用。很自然的，容器(Container)之间应用、服务的伸缩，就显得很简单了。其基因层面支持集群特性，当然，你也可以解读为云环境的支持。

部署

测试主机环境为CentOS release 6.5 (Final)，内核为2.6.32-431.el6.x86_64。我们
1.安装依赖软件
1. Virtualbox-5.0，为vagrant提供虚拟化支持
2. vagrant_1.8.1，ruby开发，使用Virtualbox等提供虚拟化支持，可跨平台部署
3. coreos-vagrant，为vagrant提供的coreos镜像

2.安装Virtualbox-5.0

cd /etc/yum.repos.d
wget http://download.virtualbox.org/virtualbox/rpm/el/virtualbox.repo
rpm -Uvh http://ftp.jaist.ac.jp/pub/Linux/Fedora/epel/7/x86_64/e/epel-release-7-5.noarch.rpm
yum install gcc make patch  dkms qt libgomp kernel-headers kernel-devel fontforge binutils glibc-headers glibc-devel -y
cd cd /usr/src/kernels/
#若不添加软连接，安装会报错
ln -s 3.10.0-327.10.1.el7.x86_64 3.10.0-327.el7.x86_64
export KERN_DIR=/usr/src/kernels/3.10.0-327.el7.x86_64
yum install VirtualBox-5.0

3.安装vagrant

wget https://releases.hashicorp.com/vagrant/1.8.1/vagrant_1.8.1_x86_64.rpm
rpm -ivh vagrant_1.8.1_x86_64.rpm

4.快速搭建CoreOS集群

git clone https://github.com/coreos/coreos-vagrant/
cd coreos-vagrant
cp user-data.sample user-data
#获取新token
curl https://discovery.etcd.io/new
#把获取的token放到user-data文件中
vim user-data
#cloud-config

---
coreos:
  etcd2:
    discovery: https://discovery.etcd.io/2fd5c65dea14ae8b9417bde39c794af4

$update_channel='stable'

#修改集群启动虚拟机个数，默认为1
cp config.rb.sample config.rb
vim config.rb
$num_instances=1

5.启动集群

[root@test]# vagrant up
Bringing machine 'core-01' up with 'virtualbox' provider...
==> core-01: Box 'coreos-stable' could not be found. Attempting to find and install...
    core-01: Box Provider: virtualbox
    core-01: Box Version: >= 0
==> core-01: Loading metadata for box 'https://storage.googleapis.com/stable.release.core-os.net/amd64-usr/current/coreos_production_vagrant.json'
    core-01: URL: https://storage.googleapis.com/stable.release.core-os.net/amd64-usr/current/coreos_production_vagrant.json
==> core-01: Adding box 'coreos-stable' (v835.13.0) for provider: virtualbox
    core-01: Downloading: http://stable.release.core-os.net/amd64-usr/835.13.0/coreos_production_vagrant.box
    core-01: Calculating and comparing box checksum...
==> core-01: Successfully added box 'coreos-stable' (v835.13.0) for 'virtualbox'!
==> core-01: Importing base box 'coreos-stable'...
==> core-01: Matching MAC address for NAT networking...
==> core-01: Checking if box 'coreos-stable' is up to date...
==> core-01: Setting the name of the VM: coreos-vagrant_core-01_1456463236858_46275
==> core-01: Clearing any previously set network interfaces...
==> core-01: Preparing network interfaces based on configuration...
    core-01: Adapter 1: nat
    core-01: Adapter 2: hostonly
==> core-01: Forwarding ports...
    core-01: 22 (guest) => 2222 (host) (adapter 1)
==> core-01: Running 'pre-boot' VM customizations...
==> core-01: Booting VM...
==> core-01: Waiting for machine to boot. This may take a few minutes...
    core-01: SSH address: 127.0.0.1:2222
    core-01: SSH username: core
    core-01: SSH auth method: private key
==> core-01: Machine booted and ready!
==> core-01: Setting hostname...
==> core-01: Configuring and enabling network interfaces...
==> core-01: Running provisioner: file...
==> core-01: Running provisioner: shell...
    core-01: Running: inline script

6.进入coreos

[root@test]# vagrant ssh
CoreOS stable (835.13.0)

注意：我曾在虚拟机为centos系统上搭建，启动vagrant后登陆vagrant ssh报错connecttimeout。后来使用物理机为centos系统且cpu支持虚拟化，vagrant ssh登陆成功。

应用

模拟在CoreOS中通过docker一个容器，容器的环境为centos，在centos上运行应用。
1.docker查找centos镜像

core@core-01 ~ $ docker search centos
NAME                            DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
centos                          The official build of CentOS.                   1960      [OK]       
jdeathe/centos-ssh              CentOS-6 6.7 x86_64 / SCL/EPEL/IUS Repos /...   15                   [OK]
jdeathe/centos-ssh-apache-php   CentOS-6 6.7 x86_64 / Apache / PHP / PHP M...   13                   [OK]
million12/centos-supervisor     Base CentOS-7 with supervisord launcher, h...   9                    [OK]
blalor/centos                   Bare-bones base CentOS 6.5 image                8                    [OK]
nimmis/java-centos              This is docker images of CentOS 7 with dif...   7                    [OK]
torusware/speedus-centos        Always updated official CentOS docker imag...   7                    [OK]
centos/mariadb55-centos7                                                        3                    [OK]
nathonfowlie/centos-jre         Latest CentOS image with the JRE pre-insta...   3                    [OK]
nickistre/centos-lamp           LAMP on centos setup                            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]
softvisio/centos                Centos                                          1                    [OK]
lighthopper/orientdb-centos     A Dockerfile for creating an OrientDB imag...   1                    [OK]
yajo/centos-epel                CentOS with EPEL and fully updated              1                    [OK]
layerworx/centos                CentOS container with etcd, etcdctl, confd...   1                    [OK]
feduxorg/centos-postgresql      Centos Image with postgres                      1                    [OK]
timhughes/centos                Centos with systemd installed and running       0                    [OK]
lighthopper/openjdk-centos      A Dockerfile for creating an OpenJDK image...   0                    [OK]
blacklabelops/centos            CentOS Base Image! Built and Updates Daily!     0                    [OK]
grayzone/centos                 auto build for centos.                          0                    [OK]
jsmigel/centos-epel             Docker base image of CentOS w/ EPEL installed   0                    [OK]
ustclug/centos                   USTC centos                                    0                    [OK]
januswel/centos                 yum update-ed CentOS image                      0                    [OK]
ericuni/centos                  centos dev                                      0                    [OK]

2.docker拉取centos镜像

core@core-01 ~ $ docker pull centos  
Using default tag: latest
latest: Pulling from library/centos
fa5be2806d4c: Pull complete 
b4af4261cb15: Pull complete 
5d358abc5d9c: Pull complete 
2933d50b9f77: Pull complete 
Digest: sha256:1272ae53bac7bf054dd209a0b4a8629bcc39526c2a767427c7639b630a224a9e
Status: Downloaded newer image for centos:latest

3.运行应用，如打印hello,CoreOS

core@core-01 ~ $ docker run -i -t centos echo "hello,CoreOS"
hello,CoreOS
core@core-01 ~ $ docker ps -a
CONTAINER ID        IMAGE               COMMAND               CREATED             STATUS                     PORTS               NAMES
93de17ef4729        centos              "echo hello,CoreOS"   5 seconds ago       Exited (0) 5 seconds ago                       boring_lumiere
c2e5c93b92a2        centos              "/bin/bash"           2 days ago          Exited (0) 2 days ago                          high_sammet