Ruby on Rails application "migrating" into JRuby on Tomcat

JRuby is something what made me like Ruby. Actually, it's the huge reason I am leaning into Ruby. By having strong background with Java, I cannot say I am disgusted with it (as it was a trend recently to say so). I like Java, but even with the evolvment of Spring, Struts, JBoss Seam (and many others) it cannot be too competitive with PHP, Ruby, etc. languages in terms of fast launching of prototype. Eventually, people are getting back to "roots" (i.e. Java, C) when they are getting their bigger, need more options with scalability, etc. What I love about JRuby is that it helps me to run everything in JVM and when I'll need "help" from Java, it will be right here, with the easiest integration possible.

Actually, I tried to get into JRuby few times, but truth to be told, I didn't see it at the level I needed it. However, recently, I gave it another try and it was the real deal - I am about to describe my experience below.

I've got a real Web application, which will be launched in production (soon), and it is using Ruby on Rails. So, I decided to port it into JRuby.
Here we go (I'll try to explain everything from the cleanest installation possible).

First step is, obviously, downloading JRuby. I am on Mac OS X, so everything will be according my experience on this platform. It should not be too different from any Unix-other one.

In my case I keep everything in /usr/local/, so let's install JRuby right there:

olexiy@airbus:~$ curl http://dist.codehaus.org/jruby/jruby-bin-1.1.6RC1.tar.gz -o ~/Downloads/jruby-bin-1.1.6RC1.tar.gz
olexiy@airbus:~$ cd /usr/local
olexiy@airbus:/usr/local$ sudo tar -zxvf ~/Downloads/jruby-bin-1.1.6RC1.tar.gz
olexiy@airbus:/usr/local$ sudo ln -sf jruby-1.1.6RC1/ jruby

Update paths:

olexiy@airbus:~$ cat .profile | grep JRUBY
JRUBY_HOME=/usr/local/jruby; export JRUBY_HOME;
PATH=$HTTPD_HOME/bin:$JAVA_HOME/bin:$JRUBY_HOME/bin:$SCALA_HOME/bin:$FLEX_HOME/bin:$MAVEN_HOME/bin:$MYSQL_HOME/bin:$MYSQL_HOME:/opt/local/bin:/usr/local/bin/bin:/usr/local/bin/lib:/usr/local/bin:/opt/bin:/usr/bin:/usr/sbin:/opt/local/bin:/usr/local/sbin:$PATH;

(and re-login to be sure your new paths picked up).

Let's install gem's now. I am specifying exact path where to use gem from, just because I want to be on the safe side as which gem will be launched. I need JRuby's one. Later down the text, I am specifying exact paths just to let reader understand easier which thing should have been running.

olexiy@airbus:~$ sudo /usr/local/jruby/bin/gem install rails mongrel jdbc-mysql activerecord activerecord-jdbcmysql-adapter rspec rack rake jruby-openssl activesupport

We'll need also ruby-debug, and need to install it with a tiny workaround:

olexiy@airbus:~$ cd /tmp
olexiy@airbus:/tmp$ curl http://files.rubyforge.vm.bytemark.co.uk/debug-commons/ruby-debug-base-0.10.3.1-java.gem -o ruby-debug-base-0.10.3.1-java.gem
olexiy@airbus:/tmp$ sudo /usr/local/jruby/bin/gem install ruby-debug-base-0.10.3.1-java.gem
olexiy@airbus:/tmp$ sudo /usr/local/jruby/bin/gem install --ignore-dependencies ruby-debug
olexiy@airbus:/tmp$ rm ruby-debug-base-0.10.3.1-java.gem

And we need to use MySQL Connector/J (we copy it into lib/ folder of JRuby):

olexiy@airbus:~$ cd /tmp
olexiy@airbus:/tmp$ curl http://mysql.easynet.be/Downloads/Connector-J/mysql-connector-java-5.1.7.tar.gz -o mysql-connector-java-5.1.7.tar.gz
olexiy@airbus:/tmp$ tar -zxvf mysql-connector-java-5.1.7.tar.gz
olexiy@airbus:/tmp$ sudo mv mysql-connector-java-5.1.7/mysql-connector-java-5.1.7-bin.jar /usr/local/jruby/lib/
olexiy@airbus:/tmp$ rm -R mysql-connector-java-5.1.7/ mysql-connector-java-5.1.7.tar.gz

Almost ready. Here is an example of what gems do I see installed for me:

olexiy@airbus:~$ sudo /usr/local/jruby/bin/gem list --local

*** LOCAL GEMS ***

actionmailer (2.2.2)
actionpack (2.2.2)
activerecord (2.2.2)
activerecord-jdbc-adapter (0.9)
activerecord-jdbcmysql-adapter (0.9)
activeresource (2.2.2)
activesupport (2.2.2)
columnize (0.3.0)
gem_plugin (0.2.3)
jdbc-mysql (5.0.4)
jruby-openssl (0.3)
mongrel (1.1.5)
rack (0.9.1)
rails (2.2.2)
rake (0.8.3)
rspec (1.1.12, 1.1.11)
ruby-debug (0.10.3)
ruby-debug-base (0.10.3.1)
sources (0.0.1)

Even if we are done with installation, we still need to prepare our Web application. Changes are required, but they are very easy. My application is called 'titi', and the changes we'll be making are not application-specific. You need to open config/environment.rb and after:

# Bootstrap the Rails environment, frameworks, and default configuration
require File.join(File.dirname(__FILE__), 'boot')
...

need to add the following block:

# Load JDBC drivers if we run on JRuby
if RUBY_PLATFORM =~ /java/
  require 'rubygems'
  RAILS_CONNECTION_ADAPTERS = %w(jdbc)
end

Also open config/database.yml and below is an example of changed settings for "development" (and all others will require similar changes):

...
development:
 <% if RUBY_PLATFORM =~ /java/ %>
 adapter: jdbcmysql
 driver: com.mysql.jdbc.Driver
 url: jdbc:mysql://localhost/titi_development?user=root&password=
 <% else %>
 adapter: mysql
 host: localhost
 socket: /tmp/mysql.sock
 <% end %>
 encoding: utf8
 database: titi_development
 username: root
 password:
...

It's all what's needed! Here we can launch us on JRuby (from you Web app folder):

olexiy@airbus:~/repo/titi/trunk/titi$ jruby -v
jruby 1.1.6RC1 (ruby 1.8.6 patchlevel 114) (2008-12-03 rev 8263) [i386-java]
olexiy@airbus:~/repo/titi/trunk/titi$ jruby script/server

Now, we can enjoy JVM. But important part is to be able to deploy for production on (say) Tomcat. And we need Warbler for that.

olexiy@airbus:~$ sudo /usr/local/jruby/bin/gem install warbler

Now, let's ask Warble to create us config file:

olexiy@airbus:~/repo/titi/trunk/titi$ sudo /usr/local/jruby/bin/warble config

It will be created in config/warble.rb and in my case I had to uncomment there the following lines:

...
config.gems += ["activerecord-jdbcmysql-adapter", "jruby-openssl"]
...
config.gems["rails"] = "2.2.2"
...
config.webxml.rails.env = ENV['RAILS_ENV'] || 'production'
...

Now, let's build the web application into WAR:

olexiy@airbus:~/repo/titi/trunk/titi$ sudo /usr/local/jruby/bin/warble war

Once done, we will have titi.war in the Web app folder. So let' go and have it running in Tomcat. Here is a short intro how to install it (if you didn't yet):

olexiy@airbus:~$ curl http://www.signal42.com/mirrors/apache/tomcat/tomcat-5/v5.5.27/bin/apache-tomcat-5.5.27.tar.gz -o ~/Downloads/apache-tomcat-5.5.27.tar.gz
olexiy@airbus:~$ curl http://apache.deathculture.net/tomcat/tomcat-6/v6.0.18/bin/apache-tomcat-6.0.18.tar.gz -o ~/Downloads/apache-tomcat-6.0.18.tar.gz
olexiy@airbus:~$ cd /usr/local
olexiy@airbus:/usr/local$ sudo tar -zxvf ~/Downloads/apache-tomcat-6.0.18.tar.gz
olexiy@airbus:/usr/local$ sudo ln -sf apache-tomcat-6.0.18/ tomcat

Let's not forget to update paths again to have Tomcat and Java there:

olexiy@airbus:~$ cat .profile | grep CATALINA
CATALINA_HOME=/usr/local/tomcat; export CATALINA_HOME;
PATH=$HTTPD_HOME/bin:$CATALINA_HOME/bin:$JAVA_HOME/bin:$JRUBY_HOME/bin:$SCALA_HOME/bin:$FLEX_HOME/bin:$MAVEN_HOME/bin:$MYSQL_HOME/bin:$MYSQL_HOME:/opt/local/bin:/usr/local/bin/bin:/usr/local/bin/lib:/usr/local/bin:/opt/bin:/usr/bin:/usr/sbin:/opt/local/bin:/usr/local/sbin:$PATH;
olexiy@airbus:~$ cat .profile | grep JAVA
JAVA_HOME=/usr;   export JAVA_HOME;
PATH=$HTTPD_HOME/bin:$CATALINA_HOME/bin:$JAVA_HOME/bin:$JRUBY_HOME/bin:$SCALA_HOME/bin:$FLEX_HOME/bin:$MAVEN_HOME/bin:$MYSQL_HOME/bin:$MYSQL_HOME:/opt/local/bin:/usr/local/bin/bin:/usr/local/bin/lib:/usr/local/bin:/opt/bin:/usr/bin:/usr/sbin:/opt/local/bin:/usr/local/sbin:$PATH;

Ready to launch:

olexiy@airbus:~$ sudo /usr/local/tomcat/bin/catalina.sh start
Using CATALINA_BASE:   /usr/local/tomcat
Using CATALINA_HOME:   /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JRE_HOME:       /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home
olexiy@airbus:~$ ps -ax | grep tomcat
71464 ttys000    0:02.22 /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home/bin/java -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Djava.util.logging.config.file=/usr/local/tomcat/conf/logging.properties -Djava.endorsed.dirs=/usr/local/tomcat/endorsed -classpath :/usr/local/tomcat/bin/bootstrap.jar -Dcatalina.base=/usr/local/tomcat -Dcatalina.home=/usr/local/tomcat -Djava.io.tmpdir=/usr/local/tomcat/temp org.apache.catalina.startup.Bootstrap start
71466 ttys000    0:00.00 grep tomcat

It's up an running. You can check it out on http://localhost:8080/. In other terminal window we will monitor logs while we'll deploy our application.

olexiy@airbus:~$ tail -f /usr/local/tomcat/logs/catalina.out

keep this window open while the deployment will be in process. To deploy our application we just need to copy titi.war into Tomcat's deployment directory.

olexiy@airbus:~/repo/titi/trunk/titi$ sudo cp titi.war /usr/local/tomcat/webapps/

Now, breath deeply for a minute or two, point browser to http://localhost:8080/titi/ and it gives me perfect production application running on Tomcat.

That's it! Very impressive how two different technologies were easy to mix together. They do require quite few steps, but it's all well worth it.