Given the name of a box (with the VAGRANTSLASH substitution in place) under ~/.vagrant.d/boxes you will find a file named and containing the metadata_url and one or more version-number directories. These version-number directories contain the unpacked boxes. The highest-numbered version is considered the "latest installed version". To discover if a more recent version exists, vagrant fetches the info via the metadata_url.
If you are asking a slightly different question, "how does vagrant determine the version of a box used to create an existing vm?", the answer is found in ~.vagrant.d/data/machine-index/index which contains the box and version info as part of each entry in the "machines" data structure. This centralized data structure is what lets, for instance, "vagrant global-status" work and is also the reason you get a warning if you move (change the name of) a folder containing a deployed Vagrantfile. -- This mailing list is governed under the HashiCorp Community Guidelines - https://www.hashicorp.com/community-guidelines.html. Behavior in violation of those guidelines may result in your removal from this mailing list. GitHub Issues: https://github.com/mitchellh/vagrant/issues IRC: #vagrant on Freenode --- You received this message because you are subscribed to the Google Groups "Vagrant" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/vagrant-up/d13cf97a-ec66-4471-a36f-9a28a67574f1%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
