Aks-engine: Remove mlocate from nodes

[sylr]

Describe the bug

For a while we regularly had some nodes becoming unready at the same time every day leading to a lot of pods being killed.

After some investigations we found out that it was the /etc/cron.daily/mlocate script executed each day at 06:25 that was CPU starving the nodes.

Removing mlocate from the nodes fixed the problem.

[jackfrancis]

For reference, on a 16.04-LTS VM:

$ sudo cat /etc/cron.daily/mlocate
#! /bin/bash

set -e

[ -x /usr/bin/updatedb.mlocate ] || exit 0

if which on_ac_power >/dev/null 2>&1; then
    ON_BATTERY=0
    on_ac_power >/dev/null 2>&1 || ON_BATTERY=$?
    if [ "$ON_BATTERY" -eq 1 ]; then
    exit 0
    fi
fi

# See ionice(1)
if [ -x /usr/bin/ionice ] &&
    /usr/bin/ionice -c3 true 2>/dev/null; then
    IONICE="/usr/bin/ionice -c3"
fi

flock --nonblock /run/mlocate.daily.lock $IONICE /usr/bin/updatedb.mlocate

[jackfrancis]

@anhvoms What are the effects of disabling the above? And, is it practical to do so, will background (e.g., walinuxagent) processes re-pave this configuration even if we manually remove it?

[anhvoms]

@jackfrancis mlocate indexes files so that they can be quickly located using the "locate" command. On some systems it can be taxing on CPU and IO. I don't think walinuxagent has anything to do with it.

[jackfrancis]

@anhvoms thank you, so it's basically something that can be optionally removed

@johnsonshi as well in case you have any different conclusions