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Set Up and Ubuntu APT Cache
The apt-cacher-ng looks to be a self container apt caching server. Basically the apt cacher stores all the relevant apt update and upgrade related files and and acts as a proxy server to multiple clients. A handy feature to improve speed and reduce Internet bandwidth where a virtual machine server is used with multiple clients. There is another package called apt-cacher but it depends upon the installation of a separate webserver.
There is also APT-mirror that retrieves all packages from the specified public repository(s). Where as apt-cacher only retrieves each package when called and stores for subsequent use by other clients. APT caching looks the way to go and apt-cacher-ng the best overall option. I installed apt-cacher-ng on the VM server, not a VM client. The clients are setup to obtain their apt updates and upgrades via the server.
The LinuxHelp web page, How To Set up an Apt-Cache Server using "Apt-Cacher-NG" in Ubuntu 16.04 Server, provide a good description of how to setup. It is reasonably straight forward. I suggest the use of “sudo systemctl restart apt-cacher-ng”, as opposed to the old fashion “sudo /etc/init.d/apt-cacher-ng restart”.
If the non-default Cache directory is not set up correctly the program defaults to “/var/cache/apt-cacher-ng”. This quirk is covered in How to change the directory of the apt-cacher-ng downloaded packages" in Ubuntu Xenial.
Links to the Apt-Cacher NG home page and Apt-Cacher-NG User Manual.
To access apt-cacher-ng web page: “http://192.168.1.5:3142”
There is an issue with use of apt-cacher and SSL/TLS repositories. A good reference is from packagecloud:blog: Using apt-cacher-ng with SSL/TLS.