David Vollbracht

RubyGems and I had a fight. It was about what version of net-ssh we wanted to have installed on my machine. RubyGems wanted the latest (2.0.2) and I wanted a 1.x version (1.1.4). Apparently net-ssh 2 has an issue with sshing into Fedora Core 4, which I needed it to do. Specifically I needed to use capistrano 1.4.1 to deploy an app to Fedora Core 4

This is something I’ve been doing regularly for some time, but ever since the MacBrick incident I haven’t needed these specific gems installed, so I was starting from scratch. Once I figured out what version of the gems I wanted, here was my first attempt: (I included --no-rdoc and --no-ri just to save time writing this post).

  $ sudo gem install net-ssh --version=1.1.4 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-ssh-1.1.4
    1 gem installed
  $ sudo gem install capistrano --version=1.4.1 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-ssh-2.0.2
    Successfully installed net-sftp-2.0.1
    Successfully installed capistrano-1.4.1
    3 gems installed

Clearly this didn’t work so well. Installing capistrano installed the latest version of net-ssh. But why? Capistrano’s gemspec for 1.4.1 says this

  ...
  s.add_dependency(%q<net-ssh>, [">= 1.0.10"])
  s.add_dependency(%q<net-sftp>, [">= 1.1.0"])
  ...

But net-sftp 2.0.1’s gemspec says it needs net-ssh 1.99.1. So we need to install specific version of both. So, attempt number two.

  $ sudo gem install net-ssh --version=1.1.4 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-ssh-1.1.4
    1 gem installed
  $ sudo gem install net-sftp --version=1.1.0 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-ssh-2.0.2
    Successfully installed net-sftp-1.1.0
    2 gems installed

Rats. Even though net-sftp 1.1.0 only specifies that it depends on net-ssh >= 1.0.0, RubyGems went ahead and installed the latest version anyway. It assumed that even though the dependency was satisfied, I want the latest version of net-ssh— exactly what I’m trying to avoid.

Armed with this information, I made one last ditch attempt.

  $ sudo gem install capistrano --version=1.4.1 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-ssh-2.0.2
    Successfully installed net-sftp-2.0.1
    Successfully installed capistrano-1.4.1
    3 gems installed
  $ sudo gem install net-ssh --version=1.1.4 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-ssh-1.1.4
    1 gem installed
  $ sudo gem install net-sftp --version=1.1.0 --no-rdoc --no-ri
    Bulk updating Gem source index for: http://gems.rubyforge.org/
    Successfully installed net-sftp-1.1.0
    1 gem installed
  $ sudo gem uninstall net-sftp net-ssh

    Select gem to uninstall:
     1. net-sftp-1.1.0
     2. net-sftp-2.0.1
     3. All versions
    > 2
    Successfully uninstalled net-sftp-2.0.1

    Select gem to uninstall:
     1. net-ssh-1.1.4
     2. net-ssh-2.0.2
     3. All versions
    > 2
    Successfully uninstalled net-ssh-2.0.2

Finally, by letting RubyGems install the latest version of net-ssh and net-sftp, then installing the versions I wanted, and the uninstalling the offending versions, I was able to get into a working state to deploy. Hopefully I’ll never run into this problem again. If you should be so unlucky, however, I hope this knowledge will help you.