Ruby gem mysql2 install failing

Question

When I try to install the mysql2 gem, it fails with no apparent errors. Does anyone know what to do to work around this so mysql2 installs?

$ sudo gem install mysql2
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
    ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
checking for rb_thread_blocking_region()... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
checking for mysql_query() in -lmysqlclient... 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=/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
    --with-mysql-config
    --without-mysql-config
    --with-mysql-dir
    --without-mysql-dir
    --with-mysql-include
    --without-mysql-include=${mysql-dir}/include
    --with-mysql-lib
    --without-mysql-lib=${mysql-dir}/lib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-mlib
    --without-mlib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-zlib
    --without-zlib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-socketlib
    --without-socketlib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-nsllib
    --without-nsllib
    --with-mysqlclientlib
    --without-mysqlclientlib
    --with-mygcclib
    --without-mygcclib
    --with-mysqlclientlib
    --without-mysqlclientlib


Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/mysql2-0.2.6 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/mysql2-0.2.6/ext/mysql2/gem_make.out

Answer 1

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

Answer 2

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.

Answer 3

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