[TriLUG] Vagrant image mentioned in Ansible presentation last night

[Phil Smith via TriLUG]

As this wasn't related directly to Ansible, I didn't want to sidetrack the presentation with the oversized Vagrant image Joseph mentioned.

1) The probable cause of the image increasing from 0.3G to 1.3G was the '*.deb' package files downloaded during the upgrade.  Use 'apt-get clean'.  On Gentoo I manually delete old /usr/portage/distfiles/*.tgz since they will be downloaded again if needed, and in about a year of updates this directory will dwarf the OS.  Since Gentoo often points directly upstream, there is a danger that a package may be abandoned either by the maintainer or Gentoo, so in that case one would want to save an obscure package before it vanishes forever.


2) Upgrading a 6 year old image to current does not necessarily produce the same system continuous updates over the 6 years would as sometimes temporary build bridge code across major updates appears.  In many cases it may even fail in non-LTS systems as it is assumed one will not start that far back.  The old "system test" concept is also violated because test groups do not test this path.  The real breakage points are crossed with upgrades to gcc and glibc.  In the case of rolling-release distros one downloads the most recent build (usually less than 1 week old) and then does a small update.  It is easier to see how starting from an older image can produce a different end result in a source-based system where one actually recompiles a new gcc (since the first try was built with the previous gcc), then recompiles the system, especially the libraries gcc uses, then repeat since you finally have gcc+new_system_libs all current which is the definition of truly having a "real" gcc-4.9.3 (this takes perhaps days and is done only by someone who wants to be really sure everything is current.  Although gcc/g++ is getting better, sometimes one has to search for a newer/older version to successfully build a package like libreoffice with 'Segmentation Fault' on fancy C++ code.