Proposal: Support for loading .env files

[fgrehm]

I've started to notice that a lot of people have been using environmental variables to make Vagrantfiles more dynamic so I was wondering if it would make sense to have this bundled on Vagrant's core instead of making a separate plugin for it.

As an example of usage, you can check Docker's Vagrantfile as they've been using it for setting things like base boxes names / URLs.

@mitchellh I did some testing with dotenv and it can give us a nice head start as it would be as simple as a adding a Dotenv.load during Vagrant's loading process:

$ vagrant plugin install dotenv
$ echo 'BOX_NAME=foo-bar' > .env
$ cat <<STR > Vagrantfile
Dotenv.load
puts "BOX_NAME is set to #{ENV['BOX_NAME']}"
STR
$ vagrant status
# outputs "BOX_NAME is set to foo-bar"

WDYT?

[fgrehm]

Oh, I'd just suggest that we default to give preference to a .vagrant.env in favor of .env as some people might depend on a .env for foreman and it could confuse some folks ;)

[mitchellh]

I'm not a big fan of this. I think instead what I want to introduce is the concept of user variables within Vagrant just like Packer.

[fgrehm]

Oh, that's fancy! I haven't used Packer's user variables before, I'm playing with Packer as of this writing and will see if I can think of something for Vagrant :)