Install failed on Ubuntu with Ruby 2.1

[gregelin]

Description

gem install inspec failed when ran as root on Ubuntu 15 with Ruby 2.1 installed.

InSpec and Platform Version

Distributor ID: Ubuntu
Description: Ubuntu 15.10
Release: 15.10
Codename: wily

Replication Case

1. Start with Ubuntu 15.10 64 bit on Digital Ocean
2. Assume root
3. Run apt-get update to update packages
4. Run apt-get install ruby -y
5. Check ruby version with ruby -v
6. Run gem install inspec

Possible Solutions

I have not dug very deeply into the issue. It is possible I am missing dev tools on server, or ruby dev tools.

Stacktrace

root@kbs:~# which ruby
/usr/bin/ruby
root@kbs:~# ruby -v
ruby 2.1.5p273 (2014-11-13) [x86_64-linux-gnu]
root@kbs:~# gem install inspec
Fetching: excon-0.49.0.gem (100%)
Successfully installed excon-0.49.0
Fetching: docker-api-1.26.2.gem (100%)
Successfully installed docker-api-1.26.2
Fetching: mixlib-shellout-2.2.6.gem (100%)
Successfully installed mixlib-shellout-2.2.6
Fetching: bcrypt_pbkdf-1.0.0.alpha1.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing inspec:
    ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.1.0/gems/bcrypt_pbkdf-1.0.0.alpha1 for inspection.
Results logged to /var/lib/gems/2.1.0/extensions/x86_64-linux/2.1.0/bcrypt_pbkdf-1.0.0.alpha1/gem_make.out

[gregelin]

Install error was result of not having ruby dev files and can be checked corrected with:

apt-get install ruby-dev

But an example execution then fails on same server. See issue #642.

[chris-rock]

@gregelin Thank you very much for the feedback. I close this issue in favor for #646 Do not hesitate to reopen if required.

[arlimus]

@gregelin We added instructions for installation from source to the readme:

apt-get -y install ruby ruby-dev gcc make

Feel free to reopen this if it still fails.