Docker base image with PostgreSQL 10 released

> df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            2.0G     0  2.0G   0% /dev
tmpfs           396M   41M  355M  11% /run
/dev/vda1        58G   27G   32G  47% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/vda15      105M  3.4M  102M   4% /boot/efi
/dev/sda1       246G   56G  178G  24% /mnt/volume-fra1-01-part1
tmpfs           396M     0  396M   0% /run/user/0

Upgrading PostgreSQL from version 9.5 to 10
WARNING: Upgrading PostgresSQL would require an addtional 1.5M of disk space
Please free up some space, or expand your disk, before continuing.

So, is the issue with /dev/vda1?
If so, should a swap file help?
If not, what do I do next?

I tried to remove a backup, which was 1GB, but it didn’t help.