bundleしたらtherubyracerでエラー

therubyracerをインストールしようとするとエラーが起きた時のメモ。

.......

Installing therubyracer (0.11.0) with native extensions 

Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
        /home/kjdev/.rvm/rubies/ruby-1.9.3-p327/bin/ruby extconf.rb 

checking for main() in -lpthread... yes

checking for v8.h... no


    
extconf.rb failed ***
    
Could not create Makefile due to some reason, probably lack of

necessary libraries and/or headers.  Check the mkmf.log file for more

details.  You may need configuration options.
Provided configuration options:

        --with-opt-dir

        --without-opt-dir

        --with-opt-include

        --without-opt-include=${opt-dir}/include

        --with-opt-lib

        --without-opt-lib=${opt-dir}/lib

        --with-make-prog

        --without-make-prog

        --srcdir=.

        --curdir

        --ruby=/home/kjdev/.rvm/rubies/ruby-1.9.3-p327/bin/ruby

        --with-pthreadlib

        --without-pthreadlib

        --enable-debug

        --disable-debug

        --with-v8-dir

        --without-v8-dir

        --with-v8-include

        --without-v8-include=${v8-dir}/include

        --with-v8-lib

        --without-v8-lib=${v8-dir}/lib

/home/kjdev/.rvm/gems/ruby-1.9.3-p327/gems/therubyracer-0.11.0/ext/v8/build.rb:42:in `build_with_system_libv8': unable to locate libv8. Please see output for details (RuntimeError)

        from extconf.rb:22:in `
'

    The Ruby Racer requires libv8 ~> 3.11.8

    to be present on your system in order to compile

    and link, but it could not be found.
    In order to resolve this, you will either need to manually

    install an appropriate libv8 and make sure that this

    build process can find it. If you install it into the

    standard system path, then it should just be picked up

    automatically. Otherwise, you'll have to pass some extra

    flags to the build process as a hint.
    If you don't want to bother with all that, there is a

    rubygem that will do all this for you. You can add

    following line to your Gemfile:

        gem 'libv8', '~> 3.11.8'
    We hope that helps, and we apologize, but now we have

    to push the eject button on this install.
    thanks,

    The Mgmt.
Gem files will remain installed in /home/kjdev/.rvm/gems/ruby-1.9.3-p327/gems/therubyracer-0.11.0 for inspection.

Results logged to /home/kjdev/.rvm/gems/ruby-1.9.3-p327/gems/therubyracer-0.11.0/ext/v8/gem_make.out

An error occurred while installing therubyracer (0.11.0), and Bundler cannot continue.

Make sure that `gem install therubyracer -v '0.11.0'` succeeds before bundling.

ログを見るとv8というjavascriptエンジンが入っていなかったかららしい。

checking for v8.h... no

gem install libv8

bundle通ったお。