How do I install mysql2 gem under Ruby 1.9.3? Works under 2.0.0

Question

I'm having trouble installing the mysql2 gem on my machine.

I have OS X 10.8 with the latest Xcode, and mySql installed via Homebrew. All rubies installed using the latest RVM.

I can install mysql2 fine under ruby 2.0.0-p195

[~]$ rvm use 2.0.0                                                              [ruby-1.9.3-p429]
Using /Users/aselder/.rvm/gems/ruby-2.0.0-p195
[~]$ gem in mysql2                                                              [ruby-2.0.0-p195]
Fetching: mysql2-0.3.11.gem (100%)
Building native extensions.  This could take a while...
Successfully installed mysql2-0.3.11
1 gem installed

Under Ruby 1.9.3 and 1.8.7, it can't find the mysql.h file

    [~]$ rvm use 1.9.3                                                              [ruby-1.9.3-p429]
    Using /Users/aselder/.rvm/gems/ruby-1.9.3-p429
    [~]$ gem in mysql2                                                              [ruby-1.9.3-p429]
    Fetching: mysql2-0.3.11.gem (100%)
    Building native extensions.  This could take a while...
    ERROR:  Error installing mysql2:
        ERROR: Failed to build gem native extension.

            /Users/aselder/.rvm/rubies/ruby-1.9.3-p429/bin/ruby extconf.rb
    checking for rb_thread_blocking_region()... yes
    checking for rb_wait_for_single_fd()... yes
    checking for mysql.h... no
    checking for mysql/mysql.h... no
    -----
    mysql.h is missing.  please check your installation of mysql and try again.
    -----
    *** 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
        --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=/Users/aselder/.rvm/rubies/ruby-1.9.3-p429/bin/ruby
        --with-mysql-config
        --without-mysql-config


    Gem files will remain installed in /Users/aselder/.rvm/gems/ruby-1.9.3-p429/gems/mysql2-0.3.11 for inspection.
    Results logged to /Users/aselder/.rvm/gems/ruby-1.9.3-p429/gems/mysql2-0.3.11/ext/mysql2/gem_make.out

I've also tried all varieties of the command line options to get the gem to find the mysql installation:

eg gem install mysql2 -- --with-mysql-config=/usr/local/opt/mysql/bin/mysql_config

Answer 1

I found this answer and it solved my issues: Error installing mysql2: Failed to build gem native extension

Quoting:

On Ubuntu/Debian and other distributions using aptitude:

sudo apt-get install libmysql-ruby libmysqlclient-dev

On Red Hat/CentOS and other distributions using yum:

sudo yum install mysql-devel

On Mac OS X with Homebrew:

brew install mysql

I'm on debian and after running the above command, I ran:

gem install mysql2

and it worked np.

Answer 2

I solve the problem installing the gem with the mysql server started!

brew install mysql

mysql.server start

bundle install

Under ruby-1.9.3-p125.

Hope this helps

Answer 3

Try to install mysql using Homebrew and the mysql2 gem using Bundler.

brew update
brew install mysql

Add the following to your Gemfile

gem "mysql2"

Run:

bundle install

Answer 4

I resolved the issue by downgrading mysql from 5.6 to 5.5 through homebrew. Can't provide a more detailed explanation, but it fixed it.

Answer 5

I had a very silly solution to this: I opened Xcode and accepted the license agreement. Update downloaded a new version and I couldn't compile anything until the new agreement was manually accepted.