• Upstart Intro, Cookbook and Best Practises, 看这个文档就够了

Upstart is an event-based replacement for the /sbin/init daemon which handles:

1. starting of tasks and services during boot
2. stopping them during shutdown
3. and supervising them while the system is running.

Upstart 里, stanza ¹⁾ == 配置.

一个基础的 upstart 配置如下:

$ cat /etc/init/cron.conf
# cron - regular background program processing daemon
#
# cron is a standard UNIX program that runs user-specified programs at
# periodic scheduled times
 
description	"regular background program processing daemon"
 
# 最普通的启动/关闭事件
start on runlevel [2345]
stop on runlevel [!2345]
 
# 文档后面有详述
expect fork
 
# 异常退出后会重启
respawn
 
# 启动的命令
exec cron
 
############################# EOF #############################
 
# ps 可看出进程在运行
$ ps aux  |grep cron
root       825  0.0  0.0  21328   404 ?        Ss   Apr01   0:05 cron
 
# upstart 也有 status 和 initctl list 可查看 service 的状态
$ status cron
cron start/running, process 825
$ initctl list | grep  cron
cron start/running, process 825

一些关键的配置如下.

如果要 使用不同配置开启一个服务的多个实例 (instance), 可如下操作 (例子为统一管理 node 相关的服务):

1. 编写 instance 的 upstart conf

   instance.conf

   description 'node upstart script'
   author 'iain'
    
   start on (local-filesystems and net-device-up)
   stop on shutdown
    
   instance "Node - $NAME"
    
   respawn
   respawn limit 5 60
    
   script
     . /etc/node/$NAME.conf
     exec sudo -u node NODE_ENV=${NODE_ENV} /usr/bin/n use ${NODE_VERSION} ${NODE_PATH} >> ${LOG_PATH} 2>&1
   end script

2. 编写每个 instance 的配置, 例如

   /etc/node/foo.conf

   NODE_VERSION="0.6.5"
   NODE_PATH="/var/application/test/app.js"
   LOG_PATH="/var/log/node/test.log"
   NODE_ENV="production"

3. 启动某个 instance 的方法如下

   $ sudo start node NAME=foo

4. 编写管理所有 instance 的 task 的 upstart conf

   task.conf

   description 'Start all node instances at boot'
   author 'iain'
    
   start on (local-filesystems and net-device-up)
    
   task
    
   script
     for file in `ls /etc/node/*.conf` ; do
       filename=`basename ${file%.*}`
       start node NAME=$filename
     done
   end script

5. 这样, 因为 task 是遍历 /etc/node/*.conf, 所以只要在 /etc/node/ 下有 conf, 服务器启动时就能由 task 按该 conf 启动服务

参考: Upstart and Node.js | Clock