gem install mysql -v 2.8.1
Building native extensions.  This could take a while...
ERROR:  Error installing mysql:
	ERROR: Failed to build gem native extension.

    /home/griensu/.rvm/rubies/ruby-2.2.0/bin/ruby -r ./siteconf20150113-12769-mhx29u.rb extconf.rb
checking for mysql_ssl_set()... yes
checking for rb_str_set_len()... yes
checking for rb_thread_start_timer()... no
checking for mysql.h... yes
*** 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/griensu/.rvm/rubies/ruby-2.2.0/bin/$(RUBY_BASE_NAME)
	--with-mysql-config
	--without-mysql-config
extconf.rb:67:in `<main>': uninitialized constant Config (NameError)

extconf failed, exit code 1

Gem files will remain installed in /home/griensu/.rvm/gems/ruby-2.2.0/gems/mysql-2.8.1 for inspection.
Results logged to /home/griensu/.rvm/gems/ruby-2.2.0/extensions/x86_64-linux/2.2.0/mysql-2.8.1/gem_make.out