====================================
In order to mount a USB or NVMe drive into containers, we first need to setup a udev rule in balenaOS. This rule needs to be added to the device config.json before flashing the device or manually via an ssh connection to the hostOS.
Add the following udev rule to config.json:
"os": {
"udevRules": {
"66": "ACTION==\"add\", SUBSYSTEMS==\"usb\", SUBSYSTEM==\"block\", ENV{ID_FS_USAGE}==\"filesystem\", RUN{program}+=\"/usr/bin/systemd-mount --no-block --automount=yes --bind-device --options=noexec,nosuid,nodev,sync --collect $devnode /run/mount/ext\"\n"
"67": "ACTION==\"add\", SUBSYSTEMS==\"nvme\", KERNEL==\"nvme[0-9]n[0-9]\", ENV{ID_FS_USAGE}==\"filesystem\", RUN{program}+=\"/usr/bin/systemd-mount --no-block --automount=yes --bind-device --options=noexec,nosuid,nodev,sync --collect $devnode /run/mount/ext\"\n"
}
},
Rule 66 is for USB and 67 is for NVMe drives, you only need to include the rule for the drive type you want to support.
Once you have added the rules, reboot the device. Now anytime an external USB or NVMe drive is plugged in, the rule will automatically mount that drive under /run/mount/ext.
Now in order to make the drive available to containers we need to create a volume that bind-mounts the location in /run to a named volume in our composition. To do this we add the following to our compose.yaml:
volumes:
test-volume:
driver: local
driver_opts:
type: none
o: bind,rshared
device: /run/mount
This will create a named volume called test-volume that is mounted to the host /run/mount/ directory.
WARNING!!! : It is not supported to mount anything outside of /run/mount for now as balenaOS makes no guarentees that those files and directories will exist in future versions.
Once we have the named volume, we can use it in any of our container services with the usual named volume syntax, like this:
services:
app1:
build:
context: ./app1
volumes:
- 'test-volume:/data'
app2:
image: my-image
volumes:
- 'test-volume:/app'