Building and installing the Ruby mysql gem on freshly-installed Red Hat based systems sometimes produces the frustratingly ambiguous error below:
# gem install mysql /usr/bin/ruby extconf.rb checking for mysql_ssl_set()... no checking for rb_str_set_len()... no checking for rb_thread_start_timer()... no checking for mysql.h... no checking for mysql/mysql.h... 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.
Searching the web for info on this error yields two basic solutions:
- Install the mysql-devel package (this provides the mysql.h file in /usr/include/mysql/).
- Run gem install mysql -- --with-mysql-config=/usr/bin/mysql_config or some other additional options.
These are correct but not sufficient. Because this gem compiles a library to interface with MySQL's C API, the gcc and make packages are also required to create the build environment:
# yum install mysql-devel gcc make # gem install mysql -- --with-mysql-config=/usr/bin/mysql_config