Setup the mirror by following the steps described here Show archive.org snapshot .

Rails Long Term Support

Rails LTS provides security patches for old versions of Ruby on Rails (2.3, 3.2, 4.2 and 5.2)

• Prevents you from data breaches and liability risks
• Upgrade at your own pace
• Works with modern Rubies

Read more Show archive.org snapshot

If you want to enable OS upgrades using do-release-upgrade make sure you include $release-proposed packages in the mirror script, e.g., precise-proposed. Additionally, you have to add main/dist-upgrader-all to the $section in your script as debmirror silently ignores some directories.

I attached our modified script to include current releases

Enable Ubuntu release upgrade from the local mirror

Download the following two files into the root document directory of your local mirror:

wget http://changelogs.ubuntu.com/meta-release
wget http://changelogs.ubuntu.com/meta-release-lts

Open both files, replace the hostname archive.ubuntu.com with your local mirror.

Run release upgrade on client machine

On the client machine you want to do the release upgrade, modify /etc/update-manager/meta-release such that

URI = http://$mirror/meta-release
URI_LTS = http://$mirror/meta-release-lts

Run do-release-upgrade, it should now use your local mirror.