如何在RancherOS系统中动态挂载外部USB硬盘？

Hey there! I’ve set up this exact workflow on RancherOS before, so let me break it down into actionable steps for you:

1. 创建udev规则实现自动挂载/卸载USB硬盘 #

RancherOS uses udev for hardware event handling, so we’ll create a rule to automatically mount USB drives when they’re plugged in, and clean up when they’re removed.

• First, create a udev rule file:

  sudo vi /etc/udev/rules.d/90-usb-drive.rules
  

• Paste the following content into the file (adjust mount options if needed):

  # Auto-mount USB drives
  ACTION=="add", SUBSYSTEM=="block", KERNEL=="sd*[0-9]", ENV{ID_BUS}=="usb", \
      RUN+="/usr/bin/mkdir -p /mnt/usb-drives/%k", \
      RUN+="/usr/bin/mount -o rw,relatime /dev/%k /mnt/usb-drives/%k", \
      MODE="0775"
  
  # Auto-unmount and clean up when USB drives are removed
  ACTION=="remove", SUBSYSTEM=="block", KERNEL=="sd*[0-9]", ENV{ID_BUS}=="usb", \
      RUN+="/usr/bin/umount -l /mnt/usb-drives/%k", \
      RUN+="/usr/bin/rmdir /mnt/usb-drives/%k"
  

  • %k will be replaced with the device name (like sdb1) so each drive gets its own unique mount point under /mnt/usb-drives.
  • Add uid=1000,gid=1000 to the mount options if you need to match a specific user/group for container access.

• Reload udev rules to apply changes immediately:

  sudo udevadm control --reload-rules
  

2. 验证自动挂载功能 #

Plug in your USB drive and check if it’s mounted:

# List mounted drives
mount | grep /mnt/usb-drives

# Check the mount point directory
ls /mnt/usb-drives

You should see your drive’s content listed. Try unplugging it— the mount point directory should be removed automatically.

3. 让容器访问USB挂载点 #

Now that the drive is mounted to /mnt/usb-drives/<device-name>, you can bind-mount this path directly into your containers.

Example: Run a container with access to the USB drive #

docker run -d \
  --name my-usb-aware-container \
  -v /mnt/usb-drives/sdb1:/container/usb-mount \
  nginx:alpine

• Replace sdb1 with your actual device name (you can find this with lsblk when the drive is plugged in).
• The path /container/usb-mount is where the drive will appear inside the container.

Handling dynamic plug/unplug #

If you need containers to automatically detect drive changes, you have a couple options:

• Script-based monitoring: Use a small sidecar container or host script that watches /mnt/usb-drives and restarts/updates containers when drives are added/removed.
• Docker Volume Plugin: For a more robust solution, use a plugin like local-persist (install it on RancherOS via ros os install docker-volume-local-persist). This lets you define volumes that map to USB mount points, and containers can use these volumes dynamically.

4. 持久化配置（可选） #

RancherOS preserves changes to /etc if you’ve set up a persistent state partition. To confirm your udev rule will survive reboots, check your state config:

ros config get rancher.state

If it points to a persistent device (like /dev/sda1), your rule will stay after reboot. If not, set it with:

ros config set rancher.state.dev "/dev/your-state-partition"

内容的提问来源于stack exchange，提问作者Chris Hunt