The primary function of the Vagrantfile is to describe the type of machine required for a project, and how to configure and provision these machines. Vagrantfiles are called Vagrantfiles because the actual literal filename for the file is
Vagrantfile (casing doesn't matter).
Vagrant is meant to run with one Vagrantfile per project, and the Vagrantfile is supposed to be committed to version control. This allows other developers involved in the project to check out the code, run
vagrant up, and be on their way. Vagrantfiles are portable across every platform Vagrant supports.
The syntax of Vagrantfiles is Ruby, but knowledge of the Ruby programming language is not necessary to make modifications to the Vagrantfile, since it is mostly simple variable assignment. In fact, Ruby isn't even the most popular community Vagrant is used within, which should help show you that despite not having Ruby knowledge, people are very successful with Vagrant.
When you run any
vagrant command, Vagrant climbs up the directory tree looking for the first Vagrantfile it can find, starting first in the current directory. So if you run
/home/mitchellh/projects/foo, it will search the following paths in order for a Vagrantfile, until it finds one:
/home/mitchellh/projects/foo/Vagrantfile /home/mitchellh/projects/Vagrantfile /home/mitchellh/Vagrantfile /home/Vagrantfile /Vagrantfile
This feature lets you run
vagrant from any directory in your project.
You can change the starting directory where Vagrant looks for a Vagrantfile by setting the
VAGRANT_CWD environmental variable to some other path.
Load Order and Merging
An important concept to understand is how Vagrant loads Vagrantfiles. Vagrant actually loads a series of Vagrantfiles, merging the settings as it goes. This allows Vagrantfiles of varying level of specificity to override prior settings. Vagrantfiles are loaded in the order shown below. Note that if a Vagrantfile is not found at any step, Vagrant continues with the next step.
- Built-in default Vagrantfile that ships with Vagrant. This has default settings and should never be changed by any user of Vagrant.
- Vagrantfile packaged with the box that is to be used for a given machine.
- Vagrantfile in your Vagrant home directory (defaults to
~/.vagrant.d). This lets you specify some defaults for your system user.
- Vagrantfile from the project directory. This is the Vagrantfile that you'll be modifying most of the time.
At each level, settings set will be merged with previous values. What this exactly means depends on the setting. For most settings, this means that the newer setting overrides the older one. However, for things such as defining networks, the networks are actually appended to each other. By default, you should assume that settings will override each other. If the behavior is different, it will be noted in the relevant documentation section.
Available Configuration Options
You can learn more about the available configuration options by clicking the relevant section in the left navigational area.