Warbler

= Warbler {rdoc-image:https://img.shields.io/gem/v/warbler}[https://rubygems.org/gems/warbler] {rdoc-image:https://github.com/jruby/warbler/actions/workflows/ci.yml/badge.svg}[https://github.com/jruby/warbler/actions/workflows/ci.yml]

Warbler is a gem to make a Java jar or war file out of any Ruby, Rails or Rack application. Warbler provides a minimal, flexible, Ruby-like way to bundle up all of your application files for deployment to a Java environment.

Warbler provides a sane set of out-of-the box defaults that should allow most Ruby applications to assemble and Just Work.

Version 2.1.x of Warbler supports versions of JRuby from 9.4 to 10.0.

Version 2.0.x (EOL) of Warbler supports versions of JRuby from 9.2 to 9.3.

Version 1.4.x (EOL) of Warbler supports versions of JRuby up to 1.7.x.

== Getting Started

1. Install the gem: <tt>gem install warbler</tt>.

2. Run warbler in the top directory of your application: <tt>warble</tt>.

3. Choose one:

• For a web project, deploy your +myapp.war+ file to your favorite Java application server.

• For a standalone applications, just run it: <tt>java -jar myapp.jar</tt>.

== Usage

Warbler's +warble+ command is just a small wrapper around Rake with internally defined tasks.

$ warble -T
warble compiled    # Feature: precompile all Ruby files
warble config      # Generate a configuration file to customize your archive
warble executable  # Feature: make an executable archive (runnable + an emb...
warble gemjar      # Feature: package gem repository inside a jar
warble pluginize   # Install Warbler tasks in your Rails application
warble runnable    # Feature: make a runnable archive (e.g. java -jar rails...
warble version     # Display version of Warbler
warble war         # Create the project war file
warble war:clean   # Remove the project war file
warble war:debug   # Dump diagnostic information

Type <tt>warble</tt> to create the jar or war file.

== Features

Warbler "features" are small Rake tasks that run before the creation of the war file and make manipulations to the archive structure. For instance, the +executable+ feature makes your war file capable of running on its own, without a servlet container (using an embedded web server) :

warble executable war

You can either add features to the warbler command line:

warble FEATURE war

or configure them in <tt>config/warble.rb</tt> to always be used.

config.features = %w(FEATURE)

Currently, the following features are available :

• +gemjar+: This bundles all gems into a single gem file to reduce the number of files in the .war. This is mostly useful for Google AppEngine where the number of files per application has a limit. (Note: not applicable for jar-based applications.)
• +runnable+: This makes a (standard Java) runnable .war archive thus you can execute binary bundled (gem) commands e.g. "rake". You should use the -S switch to specify the binary followed by any arguments in takes e.g. <tt>java -jar myrailsapp.war -S rake db:migrate</tt>.
• +executable+: This bundles an embedded web server into the .war so that it can either be deployed into a traditional java web server or run as a standalone application using <tt>java -jar myapp.war</tt>. (Note: jar-based applications are executable by default.)
• +compiled+: This uses +jrubyc+ to precompile all .rb files in your application to .class files and includes those in the .war instead of the Ruby sources. NOTE: The war file will still contain .rb files, but they will be short stubs containing the following code : <tt>load FILE.sub(/.rb$/, '.class')</tt>

Features may form the basis for a third-party plugin system (in the future) if there is demand.

NOTE: Feature tasks must be included in the same command invocation and inserted before the +war+ task in order to take effect. For example, <tt>warble compiled; warble war</tt> does not compile and obfuscate +.rb+ sources because the second invocation of +warble+ does not run the +compiled+ feature and creates a basic war with the sources included, make sure you run :

warble compiled war

or, if it's important that the war always be compiled, use the option above to put the feature in your <tt>config/warble.rb</tt>.

== .war or .jar?

War-based projects are for Rails, Merb, or Rack-based web applications. They usually contain a +config/environment.rb+ file, a +config/init.rb+ file, or a +config.ru+ file. The presence of these files are used to determine if the project is a web application, and thus a Java EE compatible war file is built for the project.

Jar-based projects are for standalone Ruby applications. Usually a Ruby application has a launcher script in the +bin+ directory and Ruby code in the <tt>lib</tt> directory. Warbler packages the application so that <tt>java -jar myapp.jar</tt> runs the launcher script.

== Jar Files

=== Gem Specification Files

If your project has a <tt>.gemspec</tt> file in the top directory, it will be used to configure the project's dependencies, launcher script, require paths, and the files to be included in the archive. For best results make sure your gemspec specifies all of the following attributes:

• +executables+
• +require_paths+
• runtime dependencies added with +add_dependency+

If your project do not have a <tt>.gemspec</tt>, Warbler will attempt to guess the launcher from the contents of the <tt>bin</tt> directory and use the <tt>lib</tt> directory as the lone require path. All files in the project will be included in the archive.

=== Bundler

Applications that use Bundler[http://gembundler.com/], detected via presence of a +Gemfile+, will have the gems packaged up into the archive along with the Gemfile. The Bundler groups named ":development", ":test" and ":assets" will be excluded by default, unless you specify with <tt>config.bundle_without</tt> in +config/warble.rb+.

Warbler supports Bundler for gems and git repositories, but not for plain path components. Warbler will warn when a +:path+ component is found in the +Gemfile+ and will refuse to include it in the archive.

=== JBundler (experimental)

Applications that use JBundler[http://github.com/mkristian/jbundler], detected via presence of a +Jarfile+, will have the jars packaged up into the archive. the JBundler gem is not needed for runtime since all jars are already part of the classloader.

== War Files

=== Rails applications

Rails applications are detected automatically and configured appropriately. The following items are set up for you:

• Your application runs in the +production+ environment by default. Change it in +config/warble.rb+ (see below).
• The Rails gem is packaged if you haven't vendored Rails (Rails <= 2.x).
• Other gems configured in Rails.configuration.gems are packaged (2.1 - 2.3)
• Multi-thread-safe execution (as introduced in Rails 2.2) is detected and runtime pooling is disabled.

=== Other Rack Applications

If you have a +config.ru+ file in the top directory or one of the immediate subdirectories of your application, it will be included and used as the rackup script for your Rack-based application. You will probably need to specify framework and application gems in +config/warble.rb+ unless you're using Bundler to manage your gems. <tt>ENV['RACK_ENV']</tt> will be set to +production+.

See {the examples in the jruby-rack project}[http://github.com/jruby/jruby-rack/tree/master/examples/] of how to configure Warbler to package Camping and Sinatra apps.

=== Configuration Notes

• Warbler will load the +environment+ Rake task in a Rails application to try to detect some configuration. If you don't have database access in the environment where you package your application, you may wish to set <tt>Warbler.framework_detection = false</tt> at the top of +config.rb+. In this case you may need to specify additional details such as booter, gems and other settings that would normally be gleaned from the app configuration.
• Is it possible to more generally detect what gems an application uses? <tt>Gem.loaded_specs</tt> is available, but the application needs to be loaded first before its contents are reliable.

== Custom Configuration

If the default settings are not appropriate for your application, you can customize Warbler's behavior. To customize files, libraries, and gems included in the .war file, you'll need a config/warble.rb file. There a two ways of doing this. With the gem, simply run

warble config

Finally, edit the +config/warble.rb+ to your taste. The generated file is fully-documented with the available options and default values.

=== Archive Layout

The default configuration puts application files (+app+, +config+, +lib+, +log+, +vendor+, +tmp+) under the .war file's +WEB-INF+ directory, and files in +public+ in the root of the .war file. Any Java .jar files stored in lib will automatically be placed in +WEB-INF/lib+ for placement on the web app's class-path.

=== web.xml

Java web applications are configured mainly through this file, and Warbler creates a suitable default file for you for use. However, if you need to customize it in any way, you have two options.

1. If you just want a static web.xml file whose contents you manually control, you may unzip the one generated for you in <tt>yourapp.war:WEB-INF/web.xml</tt> to <tt>config/web.xml</tt> and modify as needed. It will be copied into subsequent copies of the war file for you.
2. If you want to inject some dynamic information into the file, copy the <tt>WARBLER_HOME/web.xml.erb</tt> to <tt>config/web.xml.erb</tt>. Its contents will be evaluated for you and put in the webapp. Note that you can also pass arbitrary properties to the ERb template by setting <tt>config.webxml.customkey</tt> values in your <tt>config/warble.rb</tt> file.

For more information on configuration, see Warbler::Config.

== Rakefile Integration

If you'd like to control Warbler from your own p