Ubuntu-core 16.04 RPi 3 B+ Read-only file system


I created an Ubuntu-core Raspberry Pi 3 B+ image using the example shown on https://docs.ubuntu.com/core/en/guides/build-device/image-building

It was straight forward and easy to implement. Apparently the file system is read-only.

sudo usermod -aG docker $USER
usermod: /etc/group.1763: Read-only file system
usermod: cannot lock /etc/group; try again later.

Did I mess up or is that normal?

Can I have my file system read-write?



This is normal, yes, Core is focused on appliances, there is a way to use adduser with the --extrausers option to add a group, but you wouldnt be able to do that automated or from a snap easily.

the initial (development) user that you create with the initial setup tool (console-conf) has passwordless sudo access though, the docker snap should work fine with either.