swap daemon for Arch Linux

autoswap.service

[Unit]
Description=autoswap
After=local-fs.target
RequiresMountsFor=/
RequiresMountsFor=/run
RequiresMountsFor=/sys
RequiresMountsFor=/var

[Service]
Type=oneshot
RemainAfterExit=yes
TimeoutStopSec=600
Nice=-19
OOMScoreAdjust=-1000
CPUAccounting=true
ProtectHome=read-only
Environment=DISKSIZE=8G
Environment=COMP_ALGORITHM=zstd
ExecStartPre=modprobe zram num_devices=1
ExecStart=/usr/bin/sh /usr/bin/autoswap start
ExecStop=/usr/bin/sh /usr/bin/autoswap stop

[Install]
WantedBy=local-fs.target

autoswap.sh

#!/usr/bin/env bash
# Further reading: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next/+/refs/heads/akpm/Documentation/blockdev/zram.txt

function check() { rc=$?; LINE=$1; [[ $rc != 0 ]] && echo "${BASH_SOURCE[0]}:${LINE} exitted with return code ${rc}" && exit $rc; }
function usage() { echo -e 'Usage: systemctl enable|disable|start|restart|stop autoswap\nor: DISKSIZE=8G COMP_ALGORITHM=zstd autoswap start|stop\n\nConfiguration file: /etc/systemd/system/autozram.service'; }

function start() {
  [[ -z ${DISKSIZE} || -z ${COMP_ALGORITHM} ]] && usage && exit 1
  device=$(zramctl -f -s ${DISKSIZE} -a ${COMP_ALGORITHM}) || check $LINENO
  mkswap --label 'zram swap' "${device}" || check $LINENO
  swapon --priority 10 "${device}" || check $LINENO
}

function stop() {
  find /dev -name "zram*" -exec swapoff {} \;
  find /dev -name "zram*" -exec zramctl -r {} \;
}

# MAIN

[[ $UID != 0 ]] && usage && exit 1

case $1 in
start)
  start;;
stop)
  stop;;
restart)
  stop; start;;
*)
  usage;;
esac

swapon

install.sh

#!/usr/bin/env bash
# Execute:
# bash <(curl --tlsv1.2 -s https://gist.githubusercontent.com/ivanstepanovftw/e858a4c5906d4b24b483335d8db58cad/raw/install.sh)

function check() { rc=$?; LINE=$1; [[ $rc != 0 ]] && echo "${BASH_SOURCE[0]}:${LINE} exitted with return code ${rc}." && exit $rc; }

curl --tlsv1.2 -L https://gist.githubusercontent.com/ivanstepanovftw/e858a4c5906d4b24b483335d8db58cad/raw/autoswap.service -o /etc/systemd/system/autoswap.service || check $LINENO
curl --tlsv1.2 -L https://gist.githubusercontent.com/ivanstepanovftw/e858a4c5906d4b24b483335d8db58cad/raw/autoswap.sh -o /usr/bin/autoswap || check $LINENO

systemctl enable autoswap || check $LINENO
systemctl start autoswap || check $LINENO

Ubuntu 19.04

sudo apt install zram-config
sudo init-zram-swapping