OpenWrt 启动服务配置

# 前言

OpenWrt 默认并不是使用 systemd 来管理服务，而使用 go 的第三方服务包 github.com/kardianos/service 并不能有效的配置好启动项，无法被 OpenWrt 的 Web 管理所接管。因此，我们需要针对 OpenWrt 来客制化编写我们的服务。

参考资料：

• https://openwrt.org/docs/guide-developer/procd-init-scripts

# 客制化步骤

1. OpenWrt 构建自己的启动服务

   OpenWrt 后台服务主要分为两个目录，一个是 /etc/init.d/ ，另外一个是 etc/rc.d ，第一个是全部服务（包含未启用的服务），第二个是启用的服务，通常第二个目录中的服务是第一个目录中服务的软链接🔗。

2. OpenWrt 中的服务定义文件 /etc/rc.common ，这是一个通用的文件，其中包含了一些接口的定义，在本文中主要注意 start_service 这个接口，其基本的接口写法如下：

   	start_service() {
   	procd_open_instance [instance_name]
   	procd_set_param command /sbin/your_service_daemon -b -a --foo # service executable that has to run in **foreground**.
   	procd_append_param command -bar 42 # append command parameters
   	# respawn automatically if something died, be careful if you have an alternative process supervisor
   	# if process exits sooner than respawn_threshold, it is considered crashed and after 5 retries the service is stopped
   	# if process finishes later than respawn_threshold, it is restarted unconditionally, regardless of error code
   	# notice that this is literal respawning of the process, no in a respawn-on-failure sense
   	procd_set_param respawn ${respawn_threshold:-3600} ${respawn_timeout:-5} ${respawn_retry:-5}
   	procd_set_param env SOME_VARIABLE=funtimes # pass environment variables to your process
   	procd_set_param limits core="unlimited" # If you need to set ulimit for your process
   	procd_set_param file /var/etc/your_service.conf # /etc/init.d/your_service reload will restart the daemon if these files have changed
   	procd_set_param netdev dev # likewise, except if dev's ifindex changes.
   	procd_set_param data name=value ... # likewise, except if this data changes.
   	procd_set_param stdout 1 # forward stdout of the command to logd
   	procd_set_param stderr 1 # same for stderr
   	procd_set_param user nobody # run service as user nobody
   	procd_set_param pidfile /var/run/somefile.pid # write a pid file on instance start and remove it on stop
   	procd_set_param term_timeout 60 # wait before sending SIGKILL
   	procd_close_instance
   	}

   根据需要修改上述文件，主要修改 proc_set_param 和 procd_append_param 这两个参数。

   假设服务程序的二进制文件和配置文件为以下：

   • 二进制文件： /etc/bin/fzu
   • 配置文件： /etc/fzu/config.ini

   则配置文件可以写为：

   	#!/bin/sh /etc/rc.common
   	START=01
   	STOP=90
   	USE_PROCD=1
   	PROG=/usr/bin/fzu
   	start_service(){
   	procd_open_instance [fzu]
   	procd_set_param command /usr/bin/fzu # service executable that has to run in **foreground**.
   	procd_append_param command -c /etc/fzu/config.ini # append command parameters
   	# respawn automatically if something died, be careful if you have an alternative process supervisor
   	# if process exits sooner than respawn_threshold, it is considered crashed and after 5 retries the service is stopped
   	# if process finishes later than respawn_threshold, it is restarted unconditionally, regardless of error code
   	# notice that this is literal respawning of the process, no in a respawn-on-failure sense
   	procd_set_param respawn ${respawn_threshold:-3600} ${respawn_timeout:-5} ${respawn_retry:-5}
   	procd_set_param limits core="unlimited" # If you need to set ulimit for your process
   	procd_set_param file /etc/fzu/config.ini # /etc/init.d/your_service reload will restart the daemon if these files have changed
   	procd_set_param stdout 1 # forward stdout of the command to logd
   	procd_set_param stderr 1 # same for stderr
   	procd_set_param user nobody # run service as user nobody
   	procd_set_param pidfile /var/run/fzu.pid # write a pid file on instance start and remove it on stop
   	procd_set_param term_timeout 60 # wait before sending SIGKILL
   	procd_close_instance
   	}

   其中第一行是指定使用 #! /bin/sh /etc/rc.common 这个脚本来作为解释器解释上述代码，相关的 fzu 文件都需要修改成「你的启动项名称」。

3. 当上述服务配置完成后即可用下述命令获取该服务的信息：

   • 启用服务

     /etc/init.d/fzu enable

   • 启动服务

     /etc/init.d/fzu start

   • 停止服务

     /etc/init.d/fzu stop

   • 查看服务的状态

     	/etc/init.d/fzu info
     	/etc/init.d/fzu status

4. 在 OpenWrt 的管理页面中也可以看到我们的服务被接管了：

   点击 启动 、 重启 、 停止 可以轻松执行类似于 3. 中的命令。