How to Install Rails with Jruby

Jruby installation for ROR

You can't use 'therubyracer' and 'libv8' gems with JRuby.

Short answer:

Use 'therubyrhino' gem instead (https://github.com/cowboyd/therubyrhino)

Explanation:

There are some gems that can't be used under JRuby, because they are using native (C) extensions - here is a list: https://github.com/jruby/jruby/wiki/C-Extension-Alternatives

Unable to install rails with jRuby

I had this problem just a bit ago, but it was with rspec. Try this:

jruby --1.9 -S gem install rails -v 3.0.6

This tells jruby to use the ruby 1.9 interpreter.

Installing JRuby 1.6.7 + Rails 3 with Ubuntu?

First install rvm:

$ bash -s stable < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)
$ source ~/.bash_profile

Once rvm is installed, use it to install jruby:

$ rvm install jruby-1.6.7

You can then use that version:

$ rvm use jruby-1.6.7 

Finally, install rails:

$ jruby -S gem install rails

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Update

With more recent versions of rvm, installing the latest version of jruby and rails is very straightforward:

$ \curl -L https://get.rvm.io | bash -s stable --autolibs=3 --ruby=jruby --gems=rails

Installing Jruby changes default paths of Ruby and Rails

You don't need jruby in order to install therubyracer. You only need to comment out therubyracer entry in Gemfile

gem 'therubyracer', platforms: :ruby

One another way which doesn't involve therubyracer is to install node.js.

How to get rails to work with jruby and rvm - ruby version keeps flipping

what is says is definitely worth following :

Your Ruby version is 2.3.3, but your Gemfile specified 2.5.1

if you do a rvm jruby-9.1.17.0 do ruby --version you will get smt like :

jruby 9.1.17.0 (2.3.3) 2018-04-20 d8b1ff9 Java HotSpot(TM) 64-Bit Server VM 25.171-b11 on 1.8.0_171-b11 +jit [linux-x86_64]

the (2.3.3) part means its Ruby 2.3 so I recommend you use JRuby 9.2 :

rvm install jruby-9.2.8.0

will give you a 2.5(.3) compatible Ruby runtime, update Gemfile accordingly :

"ruby '2.5.3', :engine => 'jruby', :engine_version => '9.2.8.0'" 

Specifying JRuby Version in Bundler

as suggested by the comment already linking to RVM reports Gemfile ruby as not installed

RVM's support for resolving a Ruby "engine" from the Gemfile is limited and does not match how Heroku is using (parsing) the directive.

if you really want to have it both in the Gemfile use a comment for RVM e.g.

source "https://rubygems.org"
#ruby=jruby-1.7.12
if ENV["JRUBY"] || RUBY_PLATFORM == "java"
  ruby "1.9.3", engine: "jruby", engine_version: "1.7.12"
end

gem "rails", "~> 4.1.1"
# ...

jruby bundle install not working at gem 'scrypt'

You're trying to install a gem with native extensions inside a java version of ruby: usually a bad idea...

I found a pure java implementation of scrypt algorithm at https://github.com/wg/scrypt.

You need to download the jar file from Maven (http://search.maven.org/remotecontent?filepath=com/lambdaworks/scrypt/1.4.0/scrypt-1.4.0.jar), add it to your library path or require the jar in your code.

Next is to write a wrapper to imitate the scrypt behavior to use it as a drop-in replacement in your ruby/rails code.

Alternatively, you could just remove the scrypt bits and use the java library directly. Here's a snippet tested in jirb (1.7.20)...

>> require 'java'
=> true
>> require './scrypt-1.4.0.jar'
=> true
>> java_import 'com.lambdaworks.crypto.SCryptUtil'
=> [Java::ComLambdaworksCrypto::SCryptUtil]
>> passwd,n,r,p = 'secret',16384,8,1
=> ["secret", 16384, 8, 1]
>> hashed_passwd = SCryptUtil.scrypt(passwd,n,r,p)
=> "$s0$e0801$MzcxaOBVz7kaVU6E5HV0cg==$RAx9ADWVeyZE5JRl+J1NpiBSEPNabEcVdR7drddpgMw="
>> SCryptUtil.check(passwd,hashed_passwd)
=> true
>> SCryptUtil.check('wrong password',hashed_passwd)
=> false

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