I use a task-scheduler task to automatically update a container image. Unfortunately it’s a brute force method that effectively restarts the container every night, but at least it’s automatically kept up to date.
bash -c 'cat > /config/scripts/mycontainer.script' << "EOF"
#!/bin/vbash
source /opt/vyatta/etc/functions/script-template
run update container image mycontainer
run restart container mycontainer
EOF
chmod +x /config/scripts/mycontainer.script
configure
set system task-scheduler task mycontainer executable path '/config/scripts/mycontainer.script'
set system task-scheduler task mycontainer crontab-spec '00 03 * * *'
commit
save