Hi Senthil, Chris,
Thank you for your answers,
Senthil, the udev rule is triggered each time my device switch from fastboot to adb mode or from adb to fastboot mode. I tried the process of switching from adb to fastboot mode and vice versa in the container. Before that, I uninstalled fastboot and adb packages from the host so there is no way the adb and fastboot daemons of the host are creating conflicts with the fastboot and adb deamons of the container.
Each time the device enters adb mode, the udev rule is triggered and I can find the device with the command adb devices. But each time the device switchs to fastboot mode, I can 't see it with the command fastboot devices. I can see that the udev rule is triggered in the logs but the device is still not appearing. I even did a "lxc-device -n myLxcName add /dev/bus/usb/001/056" manually to add the device to the container in fastboot mode. The add process was done properly but there was still no fastboot device visible.
Chris, my container is successfully adding the usb device each time it is plugged. In adb mode, I can easily run Android CTS or Android VTS test suites on the device. So I think the container have access to "/dev/bus/usb" and also to the host's network stack.
Someone told me he had to add an additional mount entry into /usr/share/lxc/config/debian.common.conf otherwise fastboot could not see his device from the container. I will explore that option.
I am still looking for a way to fix my issue anyway.
regards,