cloud-init 介绍¶
cloud-init 是一个系统配置工具，当系统起来时， cloud-init 会从固定分区读取数据，然后执行定制化 操作。
cloud-init 有四个执行阶段：
- local: cloud-init-local.service
- init: cloud-init.service
- config: cloud-config.service
- final: cloud-final.service
配置¶
cloud-init 各阶段完成哪些工作可以在 /etc/cloud/cloud.cfg 中查看
local 阶段
作为 cloud-init 的初始阶段，此时主要完成网口的配置
/usr/bin/cloud-init init --localinit 阶段
config 阶段
final 阶段
cloud-init 脚本生成¶
社区提供了 write-mime-multipart 工具来生成 cloud-init 脚本。 使用方法如下：
$ cat my-boothook.txt
#!/bin/sh
echo "Hello World!"
echo "This will run as soon as possible in the boot sequence"
$ cat my-user-script.txt
#!/usr/bin/perl
print "This is a user script (rc.local)\n"
$ cat my-include.txt
# these urls will be read pulled in if they were part of user-data
# comments are allowed. The format is one url per line
http://www.ubuntu.com/robots.txt
http://www.w3schools.com/html/lastpage.htm
$ cat my-upstart-job.txt
description "a test upstart job"
start on stopped rc RUNLEVEL=[2345]
console output
task
script
echo "====BEGIN======="
echo "HELLO From an Upstart Job"
echo "=====END========"
end script
$ cat my-cloudconfig.txt
#cloud-config
ssh_import_id: [smoser]
apt_sources:
- source: "ppa:smoser/ppa"
$ write-mime-multipart --output=combined-userdata.txt \
my-boothook.txt:text/cloud-boothook \
my-include.txt:text/x-include-url \
my-upstart-job.txt:text/upstart-job \
my-user-script.txt:text/x-shellscript \
my-cloudconfig.txt
User Data 输入格式¶
Gzip Compressed Content
Mime Multi Part archive
User-Data Script
以
#!或Content-Type: text/x-shellscript开头。存放用户脚本，可以是 python, shell, perl 等。
user data里的脚本执行比较晚，类似 rc.local， 而且只在第一次启动时 执行。Include File
以
#include或Content-Type: text/x-include-url开头。includ file的内容是一串 url, 每行一个，cloud-init 启动时会 读取 url 链接的内容。Cloud Config Data
以
#cloud-config或Content-Type: text/cloud-config开头， 内容按规定格式编写。Upstart Job
以
#upstart-job或Content-Type: text/upstart-job开头，文件内容会存放在 /etc/init ，以供其它 job 使用。
Cloud Boothook
以
#cloud-boothook或Content-Type: text/cloud-boothook开头。boothook数据会保存到 /var/lib/cloud ，然后立刻执行。boothook每次上电都会执行，没有机制指定只运行一次。Part Handler