ERROR: Error installing astrails-safe: ERROR: Failed to build gem native extension.

[Kalistos]

I tried to install and get error.

[root@hostname ~]# sudo gem install astrails-safe --source http://gemcutter.org
Building native extensions. This could take a while...
ERROR: Error installing astrails-safe:
ERROR: Failed to build gem native extension.

/usr/bin/ruby extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/ruby.h

Gem files will remain installed in /usr/lib64/ruby/gems/1.8/gems/json-1.8.0 for inspection.
Results logged to /usr/lib64/ruby/gems/1.8/gems/json-1.8.0/ext/json/ext/generator/gem_make.out

My config:

1. cat /etc/redhat-release
   CentOS release 6.4 (Final)
2. uname -a
   Linux hosname 2.6.32-358.6.2.el6.x86_64 unit test config module #1 SMP Thu May 16 20:59:36 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
3. ruby -v
   ruby 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]
   UPD1:
4. gem -v
   2.1.5

[vitaly]

@Kalistos 1) why http://gemcutter.org and 2) what version of rubygems?

[Kalistos]

@vitaly

1. Because it is written at this page https://github.com/astrails/safe#installation. But it's no matter, I tried without " --source http://gemcutter.org" and got the same error.
2. gem -v
   2.1.5

[vitaly]

oh, i see. ;) the instructions were not upgraded in a while. anyway, I don't quite have a way to reproduce that. this gem has no native extensions of any kind. can you paste the gem_make.out?

[andyatkinson]

@vitaly I made a PR to update the install instructions to drop gemcutter. @Kalistos it looks like you have a problem with ruby on that machine if it can't find the header files. Are you able to install any gems?

1.8.7 is also considered an old version now, and the recommended versions are 1.9 or 2.0+. I would recommended closing this issue.