Zram

Because a Linux system requires swap to function properly install zram-init. To keep it simple, it will utilise RAM to store compressed swap.

Install it with:

# apk add zram-init
# rc-update add zram-init default

zram-init can be configured in /etc/conf.d/zram-init. The amount of devices and the size of zram can be changed here, for example:

num_devices=1

# swap - 500M

#size0=512
size0=`LC_ALL=C free -m | awk '/^mem:/{print int($2/4)}'`

Now the size of the swap device will be a fourth of the ram size. Reboot the computer or restart the service to check if it works.

Also be sure to read the ArchWiki for more information.