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Vagabond

  • Issue: VMs are slow.
  • Discovery: Linux has LXC, which is pretty cool.
  • Helpful: LXCs can run different distributions.
  • Implementation: Vagabond

Awesome

What is this thing?

Vagabond is a tool integrated with Chef to build local nodes easily and most importantly, quickly. It uses Linux containers instead of full blown VMs which means things are faster. Lots faster.

Vagabond is built for Chef. The tooling within Vagabond is targeted at Chef. After the initial development has slowed, the Chef specifics will be pulled into a plugin.

Installation

As a rubygem:

$ gem install vagabond

How does it work

Currently, this is built to run within a classic Chef repository. It requires a Vagabondfile file, that simply outputs a Hash. The file is Ruby though, so you can do lots of crazy stuff to build the Hash you return. Heres a simple example:

{
  :nodes => {
    :precise => {
      :template => 'ubuntu_1204',
      :run_list => ['role[base]']
    }
  },
  :server => {
    :enabled => true,
    :auto_upload => true,
    :librarian => true,
    :berkshelf => false
  }
}

We can also use the describe DSL instead of building hashes directly:

Vagabond::Vagabondfile.describe do
  nodes do
    precise do
      template 'ubuntu_1204'
      run_list ['role[base]']
    end
  end
  server do
    enabled true
    auto_upload true
    librarian true
    berkshelf false
  end
end

Now, to create a node, simply run:

$ vagabond up precise

System preparation

Vagabond will provision the host system automatically as required to create required base lxc templates and ensure proper configuration. However, we can also initialize the system directly and create required base images using the init action:

$ vagabond init

This command runs the chef recipe and generates a basic Vagabondfile and creates the base containers specified in that file. Those base containers are Ubuntu 12.04 and CentOS 6. This creation process can take a while depending on download speeds so now is a good time to get a fresh pot of coffee.

Pretty simple, right?

Templates available

Currently builtin templates:

  • ubuntu_1004
  • ubuntu_1204
  • ubuntu_1210
  • debian_6
  • debian_7
  • centos_5
  • centos_6

Commands

See the USAGE file for an overview of available commands and their usage.

Local chef server?

Yep, that's right. You can let vagabond set you up with a local chef server hanging out in a container, which all your vagabond nodes can then run against. Isolated building and testing? You betcha!

Server containers are isolated by project. This means you will have an erchef instance running in an isolated container for every project the local server option is enabled. It's just an important bit of information to remember so you can make a mental note to stop or freeze it when not in use. Or just let them run. What ever floats your boat.

Lightweight chef server

Vagabond also supports chef-zero instead of running a full blown erchef instance. You can specify this by setting it within the server block:

...
  server do
    zero true
  end
...

Vagabond knife

Since you can have a local chef server running, it can also be helpful to be able to actually interact with that server. Vagabond has commands for doing bulk uploads of assets, but you can access it too with knife to do isolated uploads, or to just do knifey things:

vagabond knife SOME COOL KNIFE COMMAND

This will just push the command into the local chef server.

Test Kitchen

Vagabond provides test kitchen 1.0 support. It will map boxes defined within platforms to platform templates available (to the best of its ability). No need to spin up vagrant VMs, or use another tool. Point vagabond at the cookbook, and let it handle the details.

In the TODO pipeline is allowing platform mapping in the Vagabondfile so custom templates (with memory limits for example) can be used instead of the base templates.

Cluster testing

Vagabond adds an extra feature to test kitchen: cluster testing. This type of testing uses the local chef server, and provides an extreme amount of power to tests. Instead of provisioning a node and simply testing it in isolation, cluster testing provides the support to provision multiple nodes against the local chef server. Once all nodes have been successfully provisioned, vagabond will go back through each node and run tests.

Seems simple, right? It is, but it's also extremely powerful. Instead of testing things individually and isolated, this allows for real integration testing. Tests can be applied to discovery, slaving, and all the other fun things nodes may be doing that require a chef server. Looking for example? See the USAGE file!

Double awesome

Infrastructure testing

Cookbook tests are great and they help keep cookbooks stable and prevent regressions. But what about tests for integrating cookbooks into an existing infrastructure? Or upgrading an existing cookbook? The tests bundled with the cookbook can happily pass with no indication of how it may affect other resources within the infrastructure. So lets fix this.

Currently infrastructure tests are built using serverspec[1]. Test kitchen support for infrastructure testing is in the works, but is still a moving target. So lets look at how we can set this up. First, initialize the specs:

$ vagabond spec init

Next, we need to define the layout of the infrastructure. This is done by populating the Layout file in the spec directory. Just like everything else, this is just a ruby file that is expected to spit out a Hash. An example file would look like this:

# spec/Layout
{
  :defaults => {
    :platform => 'ubuntu_1204',
    :environment => 'testing',
    :union => 'aufs'
  },
  :definitions => {
    :test_node => {
      :run_list => %w(role[base])
    }
  },
  :clusters => {
    :my_cluster => {
      :overrides => {
        :environment => '_default'
      },
      :nodes => ['test_node'] * 3
    }
  }
}

:defaults

These are the default configuration options used for creating the containers for testing. These are the same configurations used when creating the nodes in the Vagabondfile.

:definitions

These are the definitions of your nodes. Any options here that were defined within the :defaults section will be overridden.

:clusters

These are the clusters of nodes that describe the infrastructure. The key provides the identifier name used from the spec command. The :overrides are cluster specific overrides that are applied to all nodes when created. The :nodes is an array of :definitions keys for nodes to build. The keys can be repeated n times to provide multiple nodes of a specific type.

Usage

$ vagabond spec start my_cluster

Applying specs

Specs are applied based on the run list describing the node. After the local chef server has been created (if required), all nodes have been created, and all nodes provisioned vagabond will run back through all nodes applying the applicable specs. Specs are very straight forward and only use SSH connections to spec the node. An example spec:

require 'spec_helper'

describe 'cron' do
  it{ should be_enabled }
  it{ should be_running }
end

Spec real infrastructure

Since specs only require an SSH connection to test nodes, we can run specs against actual live infrastructure to see if it is currently in a valid state based on existing specs. Awesome!

$ vagabond spec start my_cluster --irl --environment production

Important note

Until namespaces hit Linux proper, vagabond sudos its way around. You can get around this using the setcap stuff, but it's pretty meh. If you do go that road, just turn off sudo in your Vagabond file by setting:

:sudo => false

Oh, and if you use rvm and would rather be using rvmsudo instead of boring old sudo, you can do that to:

:sudo => 'rvmsudo'

Vagabond will attempt to be smart about determining how to sudo. So if the sudo option is not set (nil) it will discover its environment and use sudo or rvmsudo accordingly.

Extra note

This thing is still very new and shiny with lots of sharp edges. They are getting sanded down as quickly as possible. If you find bugs, are confused about some of the available functionality, or just want to point out some stupidity that I have implemented, please file an issue on github!

Contributing

No hard and fast rules for contributing just preferences. I'm always happy to get help making things better!

  • Base updates and pull requests on the develop branch
  • Please don't update core files like version.rb or vagabond.gemspec

Contributors

Infos