mysql2 gem installation hell

08 Apr 2016

mysql
ruby

The current version of MySQL on homebrew is 5.7. If you need to install a previous version of the server, in my case it was 5.5, do:

brew tap homebrew/versions
brew update
brew install mysql55

This should be enough for having the server installed correctly, but it’s not enough for installing the ruby gems:

gem install mysql2 -v '0.3.11'
Building native extensions
This could take a while...
ERROR:  Error installing mysql2:
  ERROR: Failed to build gem native extension.
...
-----
mysql.h is missing.  please check your installation of mysql and try again.

To do that, you’ll need to first remove existing gems

gem uninstall mysql2

Then, link the current MySQL server with homebrew:

brew link mysql55
gem install mysql2

This worked for me 😅