通过rc.local启动docker容器内脚本

    我们常常遇到在已有镜像上开机就运行客制化脚本的需求，如果不想重新构建镜像，可以考虑本方法，利用系统的rc-local.service实现对rc.local的调用，进而启动rc.local中的客制化脚本。

    以下以centos7为例：

1 拉取镜像

root@arm:~# docker pull centos:centos7
centos7: Pulling from library/centos
Digest: sha256:be65f488b7764ad3638f236b7b515b3678369a5124c47b8d32916d6487418ea4
Status: Downloaded newer image for centos:centos7
docker.io/library/centos:centos7

2 创建容器

root@arm:~# docker run -itd --name centos7 --restart always --privileged centos:centos7 /usr/sbin/init
02d4ef44a7a7d4740c6aadc6207d8fb43ee2c16d66d3e9240f48538a39dc4a33

3 进入容器

root@arm:~# docker exec -it baota1 /bin/bash
[root@02d4ef44a7a7 /]#

4 确认运行等级，N 3表示文本多用户模式

[root@02d4ef44a7a7 /]# runlevel
N 3

5 修改/lib/systemd/system/rc-local.service，增加服务安装信息

原文件如下：

[Unit]
Description=/etc/rc.d/rc.local Compatibility
ConditionFileIsExecutable=/etc/rc.d/rc.local
After=network.target

[Service]
Type=forking
ExecStart=/etc/rc.d/rc.local start
TimeoutSec=0
RemainAfterExit=yes

在最后添加两行

[Unit]
Description=/etc/rc.d/rc.local Compatibility
ConditionFileIsExecutable=/etc/rc.d/rc.local
After=network.target

[Service]
Type=forking
ExecStart=/etc/rc.d/rc.local start
TimeoutSec=0
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

6 增加rc.local执行权限

[root@02d4ef44a7a7 ~]# chmod +x /etc/rc.d/rc.local

7 设置rc-local.service开机启动

[root@02d4ef44a7a7 ~]# systemctl enable rc-local
Created symlink from /etc/systemd/system/multi-user.target.wants/rc-local.service to /usr/lib/systemd/system/rc-local.service.

8 再次确认rc-locall.service服务状态

[root@02d4ef44a7a7 ~]# systemctl status rc-local
● rc-local.service - /etc/rc.d/rc.local Compatibility
   Loaded: loaded (/usr/lib/systemd/system/rc-local.service; enabled; vendor preset: disabled)
   Active: active (exited) since Tue 2024-03-19 14:07:54 UTC; 10min ago

Mar 19 14:07:53 02d4ef44a7a7 systemd[1]: Starting /etc/rc.d/rc.local Compati....
Mar 19 14:07:54 02d4ef44a7a7 systemd[1]: Started /etc/rc.d/rc.local Compatib....
Hint: Some lines were ellipsized, use -l to show in full.

   好了，现在可以在/etc/rc.d/rc.local添加你的脚本了。