DISTRIB_DESCRIPTION=“Ubuntu 18.04.3 LTS”
// Task: upgrade from 1.8.12 to 2.3.5.
// backed up entire folder including shared, config.env, cms_custom-ports.yml
// downloaded tarball of 2.3.5 and untarred into same folder
docker-compose -f cms_custom-ports.yml -up d
// you can see docker pulling down the new code, but when it comes back up it is still running 1.8.12
// I had a snapshot in VMware so I restored it. But I am not sure where this went wrong. I double checked the untarred docker-compose.yml file matched the source published in github and it looked fine.