#!/bin/bash
#
# Resume from hibernation on EC2 and apply workarounds for various issues
#
# Copyright (C) 2020 Canonical Ltd.
#

set -e

# Starting hibinit resume actions
echo "hibinit-resume: begin" >> /var/log/hibinit-resume.log

# Give some time to make sure the system is fully up and running, see LP: #1864041
sleep 2

# Make sure the network is properly resumed
echo "restarting network" >> /var/log/hibinit-resume.log
if grep -q xen_netfront /proc/modules; then
    # Xen netfront workaround LP: #1864041
    modprobe -r xen_netfront
    modprobe xen_netfront
fi
systemctl restart --no-block systemd-networkd

# Temporarily set memory allocation policy to "always overcommit". With
# the default overcommit policy some applications might experience
# out-of-memory errors. Setting the policy to "always overcommit" seems
# to be a safe way to prevent these errors.
OVERCOMMIT_POLICY=$(cat /proc/sys/vm/overcommit_memory)
echo 1 > /proc/sys/vm/overcommit_memory
# Start swapoff and make sure swap file is gone
while :; do
    echo "starting swapoff" >> /var/log/hibinit-resume.log
    swapoff /swap-hibinit
    if grep -q swap-hibinit /proc/swaps; then
        echo "swap still active" >> /var/log/hibinit-resume.log
        sleep 10
    else
        break
    fi
done
echo "swap disabled" >> /var/log/hibinit-resume.log
cat /proc/swaps >> /var/log/hibinit-resume.log
# Restore previou overcommit policy
echo "$OVERCOMMIT_POLICY" > /proc/sys/vm/overcommit_memory

# All done
echo "hibinit-resume: completed " >> /var/log/hibinit-resume.log