Omnibus

Easily create full-stack installers for your project across a variety of platforms.

Seth Chisamore and Christopher Maier of CHEF gave an introductory talk on Omnibus at ChefConf 2013, entitled Eat the Whole Bowl: Building a Full-Stack Installer with Omnibus:

• Video
• Slides

This project is managed by the CHEF Release Engineering team. For more information on the Release Engineering team's contribution, triage, and release process, please consult the CHEF Release Engineering OSS Management Guide.

Prerequisites

Omnibus is designed to run with a minimal set of prerequisites. You will need the following:

• Ruby 1.9+
• Bundler

Get Started

Omnibus provides both a DSL for defining Omnibus projects for your software, as well as a command-line tool for generating installer artifacts from that definition.

To get started, install Omnibus locally on your workstation.

$ gem install omnibus

You can now create an Omnibus project in your current directory by using the project generator feature.

$ omnibus new $MY_PROJECT_NAME

This will generate a complete project skeleton in the directory $MY_PROJECT_NAME

$ cd $MY_PROJECT_NAME
$ bundle install --binstubs
$ bin/omnibus build $MY_PROJECT_NAME

More details can be found in the generated project's README file.

Omnibus determines the platform for which to build an installer based on the platform it is currently running on. That is, you can only generate a .deb file on a Debian-based system. To alleviate this caveat, the generated project includes a Test Kitchen setup suitable for generating a series of Omnibus projects.

More documentation

• [Building on Debian](docs/Building on Debian.md)
• [Building on OSX](docs/Building on OSX.md)
• [Building on RHEL](docs/Building on RHEL.md)
• [Building on Windows](docs/Building on Windows.md)
• [Build Cache](docs/Build Cache.md)

Configuration DSL

Though the template project will build, it will not do anything exciting. For that, you need to use the Omnibus DSL to define the specifics of your application.

Config

If present, Omnibus will use a top-level configuration file named omnibus.rb at the root of your repository. This file is loaded at runtime and includes a number of configuration tunables. Here is an example:

# Build locally (instead of /var)
# -------------------------------
base_dir './local'

# Disable git caching
# ------------------------------
use_git_caching false

# Enable S3 asset caching
# ------------------------------
use_s3_caching true
s3_access_key  ENV['S3_ACCESS_KEY']
s3_secret_key  ENV['S3_SECRET_KEY']
s3_bucket      ENV['S3_BUCKET']

For more information, please see the Config documentation.

You can tell Omnibus to load a different configuration file by passing the --config option to any command:

$ bin/omnibus --config /path/to/config.rb

Finally, you can override a specific configuration option at the command line using the --override flag. This takes ultimate precedence over any configuration file values:

$ bin/omnibus --override use_git_caching:false

Projects

A Project DSL file defines your actual application; this is the thing you are creating a full-stack installer for in the first place. It provides a means to define the dependencies of the project (again, as specified in Software DSL definition files), as well as ways to set installer package metadata.

All project definitions must be in the config/projects directory of your Omnibus repository.

name            "chef-full"
maintainer      "YOUR NAME"
homepage        "http://yoursite.com"

install_dir     "/opt/chef"
build_version   "0.10.8"
build_iteration 4

dependency "chef"

Some DSL methods available include:

DSL Method	Description
name	The name of the project
install_dir	The desired install location of the package
build_version	The package version
build_iteration	The package iteration number
dependency	An Omnibus software-defined component to include in this package
package	Invoke a packager-specific DSL
compress	Invoke a compressor-specific DSL

For more information, please see the Project documentation.

Software

Omnibus "software" files define individual software components that go into making your overall package. They are the building blocks of your application. The Software DSL provides a way to define where to retrieve the software sources, how to build them, and what dependencies they have. These dependencies are also defined in their own Software DSL files, thus forming the basis for a dependency-aware build ordering.

All Software definitions should go in the config/software directory of your Omnibus project repository.

Here is an example:

name "ruby"
default_version "1.9.2-p290"
source url: "http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-#{version}.tar.gz",
       md5: "604da71839a6ae02b5b5b5e1b792d5eb"

dependency "zlib"
dependency "ncurses"
dependency "openssl"

relative_path "ruby-#{version}"

build do
  command "./configure"
  command "make"
  command "make install"
end

Some of the DSL methods available include:

DSL Method	Description
name	The name of the software component (this should come first)
default_version	The version of the software component
source	Directions to the location of the source
dependency	An Omnibus software-defined component that this software depends on
relative_path	The relative path of the extracted tarball
build	The build instructions

For more DSL methods, please consult the Software documentation.

Additionally, there are a number of DSL methods avaiable inside the build block:

DSL Method	Description
command	Execute a single shell command
make	Run make (with or without args), using gmake when appropriate
patch	Apply a patch from disk
workers	The maximum number of builders
windows_safe_path	Format the path to be safe for shelling out on Windows
ruby	Execute the code as the embedded Ruby
gem	Execute the code as the embedded Rubygems
bundle	Execute the code as the embedded Bundler
rake	Execute the code as the embedded Rake gem
block	Execute Ruby block at build time
erb	Render the given ERB template
mkdir	Create the given directory
touch	Create the given empty file
delete	Remove the given file or directory
copy	Copy a to b
move	Move a to b
link	Link a to b
sync	Copy all files from a to b, removing any union files

For more DSL methods, please consult the Builder documentation.

You can support building multiple verisons of the same software in the same software definition file using the version method and giving a block:

name "ruby"
default_version "1.9.2-p290"

version "1.9.2-p290" do
  source url: "http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-#{version}.tar.gz",
         md5: "604da71839a6ae02b5b5b5e1b792d5eb"
end

version "2.1.1" do
  source url: "http://ftp.ruby-lang.org/pub/ruby/2.1/ruby-#{version}.tar.gz",
         md5: "e57fdbb8ed56e70c43f39c79da1654b2"
end

Since the software definitions are simply ruby code, you can conditionally execute anything by wrapping it with pure Ruby that tests for the version number.

Sharing software definitions

The easiest way to share organization-wide software is via bundler and Rubygems. For an example software repository, look at Chef's omnibus-software. For more information, please see the Rubygems documentation.

It is recommended you use bundler to pull down these gems (as bundler also permits pulling software directly from GitHub):

gem 'my-company-omnibus-software'
gem 'omnibus-software', github: 'my-company/omnibus-software'

Then add the name of the software to the list of software_gems in your Omnibus config:

software_gems %w(my-company-omnibus-software omnibus-software)

You may also specify local paths on disk (but be warned this may make sharing the project among teams difficult):

local_software_dirs %w(/path/to/software /other/path/to/software)

For all of these paths, order matters, so it is possible to depend on local software version while still retaining a remote software repo. Given the above example, Omnibus will search for a software definition named foo in this order:

$PWD/config/software/foo.rb
/path/to/software/config/software/foo.rb
/other/path/to/software/config/software/foo.rb
/Users/sethvargo/.gems/.../my-comany-omnibus-software/config/software/foo.rb
/Users/sethvargo/.gems/.../omnibus-software/config/software/foo.rb

The first instance of foo.rb that is encountered will be used. Please note that local (vendored) softare definitions take precedence!

Caveats

Overrides

The project definitions can override specific software dependencies by passing in override to use the correct version:

name "chef-full"
# <snip>

# This will override the default version of "chef"
override :chef, version: "2.1.1"

dependency "chef"

The overridden version must be defined in the associated software!

Debugging

By default, Omnibus will log at the warn level. You can override this by passing the --log-level flag to your Omnibus call:

$ bin/omnibus build <project> --log-level info # or "debug"

Git caching

by default, Omnibus caches compiled software definitions, so n+1 Omnibus project builds are much faster. This functionality can be disabled by adding the following to your omnibus.rb:

use_git_caching false

License

Copyright 2012-2014 Chef Software, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.