gem install rmagick に失敗したときの対処

CentOS 6.3 で bundler で依存パッケージのインストール時に失敗した。エラー内容は下記。

Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /usr/local/rbenv/versions/1.9.3-p286/bin/ruby extconf.rb 
checking for Ruby version >= 1.8.5... yes
extconf.rb:128: Use RbConfig instead of obsolete and deprecated Config.
checking for gcc... yes
checking for Magick-config... no
Can't install RMagick 2.13.1. Can't find Magick-config in /usr/local/rbenv/versions/1.9.3-p286/bin:/usr/local/rbenv/libexec:/usr/local/rbenv/shims:/usr/local/rbenv/bin:/usr/lib64/qt-3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

*** 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=/usr/local/rbenv/versions/1.9.3-p286/bin/ruby


Gem files will remain installed in /usr/local/rbenv/versions/1.9.3-p286/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1 for inspection.
Results logged to /usr/local/rbenv/versions/1.9.3-p286/lib/ruby/gems/1.9.1/gems/rmagick-2.13.1/ext/RMagick/gem_make.out
An error occurred while installing rmagick (2.13.1), and Bundler cannot continue.
Make sure that `gem install rmagick -v '2.13.1'` succeeds before bundling.

どうやら ImageMagick-devel がないことが原因らしい。下記でインストール。

# yum install ImageMagick-devel

そしてまた gem install なり bundle install なりを実行すると、インストールが成功する。