Comment 5 for bug 1999816

Steps to Reproduce
---

lxc launch ubuntu:focal rmq-focal
lxc exec rmq-focal -- su - ubuntu

sudo apt install --yes rabbitmq-server

$ sudo rabbitmqctl status | grep -i disk
Free Disk Space
Low free disk space watermark: 0.05 gb
Free disk space: 327.7867 gb

DF=$(which df)
SH=/tmp/df.sh

cat <<EOF >$SH
#!/bin/sh
sleep 5m
EOF

sudo chmod +x $SH
sudo mount --bind $SH $DF

$ sudo rabbitmqctl status
Status of node rabbit@rmq-focal ...
<... DELAY ...>
Error:
{{:unparseable, []}, {:gen_server, :call, [:rabbit_disk_monitor, :get_disk_free_limit, :infinity]}}

sudo kill $(pidof sleep)
sudo umount $DF
rm $SH

For doc purposes, the chain from rabbitmq-server to the df (sleep) command:

$ ps axf | sed -n '/rabbitmq-server$/,/sleep/p'
   1973 ? Ss 0:00 /bin/sh /usr/sbin/rabbitmq-server
   1977 ? Sl 0:31 \_ /usr/lib/erlang/erts-10.6.4/bin/beam.smp ...
   2244 ? Ss 0:00 \_ erl_child_setup 65536
   2273 ? Ss 0:00 \_ inet_gethost 4
   2274 ? S 0:00 | \_ inet_gethost 4
   4237 ? Ss 0:00 \_ /bin/sh -s unix:cmd
   4238 ? S 0:00 \_ /bin/sh /usr/bin/df -kP /var/lib/rabbitmq/mnesia/rabbit@rmq-focal
   4239 ? S 0:00 \_ sleep 5m