5093f3120e
This is a big commit, and I apologize in advance for the future
git-blames all pointing to me. This commit does a few things:
1. Merges the website/docs and website/www repo into a single website repo
to be in line with other HashiCorp projects
2. Updates to use middleman-hashicorp
3. Converts less to scss to be in line with other projects
4. Updates page styles to be in line with other projects
5. Optimizes images
6. Prepare for S3 + Fastly deployment with scripts, etc.
7. Removes blog posts (they have been transferred to hashicorp.com with
redirects in place
8. Updated sitemap generation script for better SEO
9. Fixed many broken links
10. Add description to all fields
103 lines
3.6 KiB
Markdown
103 lines
3.6 KiB
Markdown
---
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layout: "docs"
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page_title: "Custom Guests - Plugin Development"
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sidebar_current: "plugins-guests"
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description: |-
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This page documents how to add new guest OS detection to Vagrant, allowing
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Vagrant to properly configure new operating systems. Prior to reading this,
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you should be familiar with the plugin development basics.
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---
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# Plugin Development: Guests
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This page documents how to add new guest OS detection to Vagrant, allowing
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Vagrant to properly configure new operating systems.
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Prior to reading this, you should be familiar
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with the [plugin development basics](/docs/plugins/development-basics.html).
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<div class="alert alert-warning">
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<strong>Warning: Advanced Topic!</strong> Developing plugins is an
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advanced topic that only experienced Vagrant users who are reasonably
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comfortable with Ruby should approach.
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</div>
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Vagrant has many features that requires doing guest OS-specific
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actions, such as mounting folders, configuring networks, etc. These
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tasks vary from operating system to operating system. If you find that
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one of these does not work for your operating system, then maybe the
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guest implementation is incomplete or incorrect.
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## Definition Component
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Within the context of a plugin definition, new guests can be defined
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like so:
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```ruby
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guest "ubuntu" do
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require_relative "guest"
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Guest
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end
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```
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Guests are defined with the `guest` method. The first argument is the
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name of the guest. This name is not actually used anywhere, but may in the
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future, so choose something helpful. Then, the block argument returns a
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class that implements the `Vagrant.plugin(2, :guest)` interface.
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## Implementation
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Implementations of guests subclass `Vagrant.plugin("2", "guest")`. Within
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this implementation, only the `detect?` method needs to be implemented.
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The `detect?` method is called by Vagrant at some point after the machine
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is booted in order to determine what operating system the guest is running.
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If you detect that it is your operating system, return `true` from `detect?`.
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Otherwise, return `false`.
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Communication channels to the machine are guaranteed to be running at this
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point, so the most common way to detect the operating system is to do
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some basic testing:
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```
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class MyGuest < Vagrant.plugin("2", "guest")
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def detect?(machine)
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machine.communicate.test("cat /etc/myos-release")
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end
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end
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```
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After detecting an OS, that OS is used for various
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[guest capabilities](/docs/plugins/guest-capabilities.html) that may be
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required.
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## Guest Inheritance
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Vagrant also supports a form of inheritance for guests, since sometimes
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operating systems stem from a common root. A good example of this is Linux
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is the root of Debian, which further is the root of Ubuntu in many cases.
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Inheritance allows guests to share a lot of common behavior while allowing
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distro-specific overrides.
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Inheritance is not done via standard Ruby class inheritance because Vagrant
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uses a custom [capability-based](/docs/plugins/guest-capabilities.html) system.
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Vagrant handles inheritance dispatch for you.
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To subclass another guest, specify that guest's name as a second parameter
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in the guest definition:
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```ruby
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guest "ubuntu", "debian" do
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require_relative "guest"
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Guest
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end
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```
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With the above component, the "ubuntu" guest inherits from "debian." When
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a capability is looked up for "ubuntu", all capabilities from "debian" are
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also available, and any capabilities in "ubuntu" override parent capabilities.
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When detecting operating systems with `detect?`, Vagrant always does a
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depth-first search by searching the children operating systems before
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checking their parents. Therefore, it is guaranteed in the above example
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that the `detect?` method on "ubuntu" will be called before "debian."
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