I reimaged my card and started over just to see if I did something wrong. Prior to starting step 27 I had 5.9G free. I still ran into an out of space error:
26f8c53f3113: Download complete
b97e5a7a66ae: Error downloading dependent layers
Error pulling image (latest) from docker.io/alarmdecoder/alarmdecoder, symlink ../init.d/mountall.sh /var/lib/docker/overlay/b97e5a7a66ae0877b3d8c394d3ff49a5660e43e456957b88c0b3b550ebcaa5ef/tmproot390715982/etc/rcS.d/S08mountall.sh: no space left on device
Failed to pull alarmdecoder image...
Afterward I checked the file system and there was still 4.4G available. I don't understand how I am getting no space errors.
Filesystem Size Used Avail Use% Mounted on
/dev/root 7.3G 2.6G 4.4G 38% /
devtmpfs 213M 0 213M 0% /dev
tmpfs 218M 0 218M 0% /dev/shm
tmpfs 218M 3.1M 215M 2% /run
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 218M 0 218M 0% /sys/fs/cgroup
/dev/mmcblk0p1 41M 21M 21M 51% /boot
tmpfs 44M 0 44M 0% /run/user/1000