Check mount point before mounting in entry.sh entry script

[nghiant2710]

Balena supervisor will bind mount the host OS /sys into the container if label io.balena.features.sysfs is set so customer might see some error like this mount: /sys/kernel/debug: nodev already mounted or mount point busy. in the logs if both UDEV and the label above is set.

The entry script should check the mount point before mounting to avoid this conflict.

[jellyfish-bot]

I have been using a custom script for USB mounting and incorporated a fix for this issue in it. The hope is to try it out for a while and check it is effective and causes no issues. The new version has also converted from the original BASH in to SH which should remove the requirement of installing bash in to Alpine containers to run the script: balena-io-experimental/starter-interface@23119f9

[jellyfish-bot]

[maggie0002] We may also want to consider using install_packages to install udev and other package requirements rather than including them in the image by default. It wouldn't work offline but we could return an error notifying the user of the packages they should include for offline use. This reduces the image size, I tend to aim for as little in the images as possible and let people build up from there, as there isn't a good way to remove things we add in.