Skyhook Mark III

A network bootable Linux live environment with an integrated masterless Chef client.

Overview

The Mark III image is a Debian based live system built and managed by the Debian live-build suite of tools. It has Opscode's Chef client pre-installed, as well as boot scripts that can retrieve cookbooks and configuration data from a remote source and apply them to the running node.

The image can be customized to suit your needs in accordance with the Debian live-build procedures. Here is a quick overview of a few common tasks:

Packages: The packages that will be installed in the image are defined in config/package-lists/*.list
Files: Files can be inserted into the boot image by placing them into their full filesystem paths under config/includes.chroot/
Hooks: Custom scripts can be run both during the image build and boot process by placing them in config/hooks/ as *.chroot (build) or *.binary (boot). For example; config/hooks/cleanup.chroot would execute while the image is being built on your machine, whereas config/hooks/ping.binary would execute when the image is booted.

Prerequisites

Tested on Ubuntu 12.10, but should build on any recent Ubuntu/Debian system
$ apt-get install debootstrap squashfs-tools live-build build-essential

Build Instructions

$ make

If successful, resultant images will be in binary/live as vmlinuz (kernel), initrd.img (initramfs), and filesystem.squashfs (the root filesystem image).

Using the Integrated Chef Environment

The image comes with Chef client preinstalled. The /usr/bin/chef-run script runs when the system boots and attempts to download and execute cookbooks and settings from sources configured in the kernel boot parameters.

The process starts by inspecting the kernel boot parameters so that chef-run can locate repositories, which are tar-gzipped archives that contain a "chef-repo" directory structure. Please refer to https://github.com/opscode/chef-repo for details regarding the layout of these directories. Once the repositories are downloaded and extracted, a runlist is used (either specified directly or as a URL containing the runlist via the chef.runlist kernel parameter). This runlist determines the order in which the recipes downloaded from one or more repositories are executed.

Chef is an extremely powerful and versatile configuration management system that can perform just about any task you require of it. If you would like to know more, consult the Chef documentation at http://docs.opscode.com/.

Kernel Parameters

Kernel Parameter	Short Version	Example Value(s)	Description
chef.skip	nochef	`true`, `false`	Specifies whether Chef should execute on boot or not (default: `false`)
chef.repo	repo	`base,install,things`	A comma-separated list of repositories to download (suffixed with .tar.gz)
chef.baseurl	repourl	http://repo.example.com/chef/repos	A URL that is prefixed to all repositories specified with `chef.repo`
chef.runlist	runlist	`role[global],recipe[os::repo]`	A comma-separated list of recipes that Chef should execute, in order
chef.runlist	runlist	`http://repo.example.com/chef/run.list`	A URL that chef-run will download a runlist file from

Runlist Files

If you specify a URL in the chef.runlist kernel parameter, chef-run will download the contents of that URL and parse it for recipes to execute. Here is an example file with valid syntax:

# Sample runlist file
# Comments are prefixed with '#' and are ignored

# So

# Are

# Blank Lines

role[base]

# other things
recipe[ntp]
recipe[nginx::server]

role[api-server]

The resultant runlist from the above file would be: role[base],recipe[ntp],recipe[nginx::server],role[api-server]

nmilford/skyhook