Juju nodes might lost connection with juju agent. This script help us to restart those jujud.

restart-jujud.sh

#!/bin/sh
# https://pastebin.canonical.com/183117/
# # trusty
# for j in $(initctl list | awk '/jujud/ {print $1}'); do echo sudo restart $j; done
# # xenial
# for j in $(systemctl list-unit-files | awk '/jujud/ {print $1}'); do echo sudo systemctl restart $j; done

for i in $(juju status --format yaml| grep 'agent lost' | awk '{print $1}');
do
## for juju 1
#for i in $(juju status --format yaml | grep 'agent is lost' | awk '{print $9}');
#do
#    i=${i:0:(-1)}
    JUJUD_LIST=`juju ssh $i initctl list | awk '/jujud/ {print $1}'`
    for JUJUD in $JUJUD_LIST; do
        juju ssh $i sudo service $JUJUD restart
    done
done

https://gist.github.com/Roadmaster/e3fde11eb4586064ab39df21bcdbaab3

similar solution