I repurposed a laptop with a broken display as an Ubuntu server on my local network. I did the installation via the Ubuntu live USB wizard and opted to have it install Docker. I didn’t realize that this would install it via snap.

Why is this a problem?

Honestly, it wasn’t.

Until I attempted to mount a volume bound to a directory under /opt/. I kept getting this error:

docker: Error response from daemon: error while creating mount source path '/cache': mkdir /cache: read-only file system.

I tried the following:

• Create the directory with my $USER and as root
• Give the directory 777 access permissions
• Verified that there was enough space in the partition

Nothing worked.

Solution

Completely remove the Docker snap

sudo snap stop docker
sudo snap remove docker

Then install Docker using the official installation instructions.