Sprinkle

Sprinkle is a software provisioning tool you can use to build remote servers with, after the base operating system has been installed. For example, to install a Rails or Merb stack on a brand new slice directly after its been created.

Installation

Install:

$ gem install sprinkle

Packages

Properties of packages such as their name, type, dependencies, etc, and what packages apply to what machines is described via a domain specific language that Sprinkle executes (in fact one of the aims of Sprinkle is to define as concisely as possible a language for installing software).

An example:

package :ruby do
  description 'Ruby Virtual Machine'
  version '1.8.6'
  source "ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-#{version}-p111.tar.gz"
  requires :ruby_dependencies

  verify do
    has_file '/usr/bin/ruby'
  end
end

This defines a package called ruby, that uses the source based installer to build Ruby 1.8.6 from source, installing the package ruby_dependencies beforehand. The package verifies it was installed correctly by verifying the file /usr/bin/ruby exists after installation. If this verification fails, the sprinkle script will gracefully stop.

Reasonable defaults are set by sprinkle, such as the install prefix, download area, etc, but can be customized globally or per package (see below for an example).

Since packages come in many forms (eg. gems, pre-compiled debs, compressed source tar.gz, etc), Sprinkle supports many different installer types, giving you the most amount of flexibility of how you'd like software installed. New installer types can be added into the system easily.

For example, you could install Rails via gems, nginx via source, and mysql via APT, while retaining the flexibility of changing installer types as software is updated upstream.

Sprinkle also supports dependencies between packages, allowing you specify pre-requisites that need to be installed in order.

Policies

Packages can be grouped into polices to define several packages that should be installed together. An example:

policy :rails, :roles => :app do
  requires :rails, :version => "3.2"
  requires :appserver
  requires :database
  requires :webserver
end

This defines a policy called Rails, that applies to machines of role :app. The policy includes the packages rails (version 3.2), appserver, database and webserver.

The appserver, database and webserver packages can also be virtual, prompting the user for selection if multiple choices for the virtual package exist.

Sprinkle is architected to be extendable in many ways, one of those areas is in its deployment of commands to remote hosts. Currently Sprinkle supports the use of Capistrano, Vlad, or a direct net/ssh connection to issue commands on remote hosts via ssh, but could also be extended to use any other command transport mechanism desired. Sprinkle can also be configured to simply issue installation commands to provision the local system.

Sprinkle is a work in progress and I'm excited to hear if anyone finds it useful - please feel free to comment, ask any questions, or send in any ideas, patches, bugs. All most welcome.

Marcus Crafter - crafterm@redartisan.com

APPENDIX

A full example deployment

A full example Sprinkle deployment script for deploying Rails (via gems), MySQL (via APT), Apache (via source) and Git (via source with dependencies from APT):

# Sprinkle Rails deployment script
#
# This is an example Sprinkle script, configured to install Rails from gems, Apache, Ruby and Git from source,
# and mysql and Git dependencies from apt on an Ubuntu system. Installation is configured to run via
# Capistrano (and an accompanying deploy.rb recipe script). Source based packages are downloaded and built into
# /usr/local on the remote system.
#
# A sprinkle script is separated into 3 different sections. Packages, policies and deployment.
#
# Packages
#
#  Defines the world of packages as we know it. Each package has a name and
#  set of metadata including its installer type (eg. apt, source, gem, etc). Packages can have
#  relationships to each other via dependencies
#
# Policies
#
#  Names a group of packages (optionally with versions) that apply to a particular set of roles.
#
# Deployment
#
#  Defines script wide settings such as a delivery mechanism for executing commands on the target
#  system (eg. capistrano), and installer defaults (eg. build locations, etc).

# Packages

package :ruby do
  description 'Ruby Virtual Machine'
  version '1.8.6'
  source "ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-#{version}-p111.tar.gz"
  requires :ruby_dependencies
end

package :ruby_dependencies do
  description 'Ruby Virtual Machine Build Dependencies'
  apt %w( bison zlib1g-dev libssl-dev libreadline5-dev libncurses5-dev file )
end

package :mysql, :provides => :database do
  description 'MySQL Database'
  apt %w( mysql-server mysql-client )
end

package :apache, :provides => :webserver do
  description 'Apache 2 HTTP Server'
  version '2.2.9'
  source "http://apache.wildit.net.au/httpd/httpd-#{version}.tar.bz2" do
    enable %w( mods-shared=all proxy proxy-balancer proxy-http rewrite cache headers ssl deflate so )
    prefix "/opt/local/apache2-#{version}"
    post :install, 'install -m 755 support/apachectl /etc/init.d/apache2', 'update-rc.d -f apache2 defaults'
  end
  requires :apache_dependencies
end

package :apache_dependencies do
  description 'Apache 2 HTTP Server Build Dependencies'
  apt %w( openssl libtool mawk zlib1g-dev libssl-dev )
end

package :rubygems do
  description 'Ruby Gems Package Management System'
  version '1.2.0'
  source "http://rubyforge.org/frs/download.php/38646/rubygems-#{version}.tgz" do
    custom_install 'ruby setup.rb'
  end
  requires :ruby
end

package :rails do
  description 'Ruby on Rails'
  gem 'rails'
  version '3.2'
end

package :mongrel do
  description 'Mongrel Application Server'
  gem 'mongrel'
  version '1.1.5'
end

package :mongrel_cluster, :provides => :appserver do
  description 'Cluster Management for Mongrel'
  gem 'mongrel_cluster' # :source => 'http://gems.github.com/' for alternate gem server
  version '1.0.5'
  requires :mongrel
end

package :git, :provides => :scm do
  description 'Git Distributed Version Control'
  version '1.5.6.3'
  source "http://kernel.org/pub/software/scm/git/git-#{version}.tar.gz"
  requires :git_dependencies
end

package :git_dependencies do
  description 'Git Build Dependencies'
  apt 'git', :dependencies_only => true
end

# Policies

# Associates the rails policy to the application servers. Contains rails, and surrounding
# packages. Note, appserver, database and webserver are all virtual packages defined above. If
# there's only one implementation of a virtual package, it's selected automatically, otherwise
# the user is requested to select which one to use.

policy :rails, :roles => :app do
  requires :rails, :version => "3.2"
  requires :appserver
  requires :database
  requires :webserver
  requires :scm
end

# Deployment

# Configures sprinkle to use capistrano for delivery of commands to the remote machines (via
# the named 'deploy' recipe). Also configures 'source' installer defaults to put package gear
# in /usr/local

deployment do

  # mechanism for deployment
  delivery :capistrano do
    recipes 'deploy'
  end

  # source based package installer defaults
  source do
    prefix   '/usr/local'           # where all source packages will be configured to install
    archives '/usr/local/sources'   # where all source packages will be downloaded to
    builds   '/usr/local/build'     # where all source packages will be built
  end

end

Please see the examples directory for more complete examples of Sprinkle deployment scripts, and also the Passenger Stack github page and video by Ben Schwarz.

sprinkle

Development