Ruby gem mysql2 install failing

Ubuntu:

sudo apt-get install libmysqlclient-dev  #(mysql development headers)
sudo gem install mysql2 -- --with-mysql-dir=/etc/mysql/

That's it!

Result:

Building native extensions. This could take a while...
Successfully installed mysql2-0.2.6
1 gem installed
Installing ri documentation for mysql2-0.2.6...
Enclosing class/module 'mMysql2' for class Result not known
Enclosing class/module 'mMysql2' for class Client not known
Installing RDoc documentation for mysql2-0.2.6...
Enclosing class/module 'mMysql2' for class Result not known
Enclosing class/module 'mMysql2' for class Client not known

You have to have 64-bit MySQL installed on your machine, plus the build tools you get when you install xcode.

You need the MySQL development headers for mysql2 to properly compile. This is needed, because much of the functionality is written in C and subsequently linked against MySQL.

A solution is to either point the gem installer to your mysql install folder explicitly like so

gem install mysql2 -- --with-mysql-dir=/usr/local/mysql
# or where ever you installed your mysql server to

or by installing a mysql server to a known location (e.g. by using homebrew.) and then installing the gem

# install the mysql server locally
brew install mysql
# install the gem
gem install mysql2

Both approaches require you to have XCode installed to have the required GCC compiler.