Updating RubyGems to Recent 1.3.x

Posted by: on Jul 29, 2009 in Blog | Tags: , | 13 Comments

The RubyGems update process can be temperamental. If you fall more than a release or two behind, you might find yourself in a dependency cycle that stops an update cold. Recently, I tried to update a 1.2.0 install to the current 1.3.5.

# gem update --system
Updating RubyGems
Updating rubygems-update
Successfully installed rubygems-update-1.3.5
ERROR:  While executing gem ... (NameError)
    undefined local variable or method `remote_gemspecs' for
#<Gem::Commands::UpdateCommand:0xb7e26640>

This is a known issue. Running the command again results in “nothing to update,” also a known issue. The fix is to separately install rubygems-update and run update_rubygems.

# gem install rubygems-update
Successfully installed rubygems-update-1.3.5
1 gem installed
Installing ri documentation for rubygems-update-1.3.5...
Installing RDoc documentation for rubygems-update-1.3.5...
Could not find main page README
Could not find main page README
Could not find main page README
Could not find main page README
# update_rubygems
/usr/lib/ruby/site_ruby/1.8/rubygems.rb:578:in `report_activate_error':
Could not find RubyGem builder (>= 0) (Gem::LoadError)
	from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:134:in `activate'
	from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:158:in `activate'
	from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `each'
	from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:157:in `activate'
	from /usr/lib/ruby/site_ruby/1.8/rubygems.rb:49:in `gem'
	from /usr/bin/update_rubygems:18

To fix this “report_activate_error”, I installed builder. Tried the update again, same thing for session and hoe-seattlerb. This is where I found myself in a dependency cycle.

rubygems-update 1.3.5 requires (among other things) hoe-seattlerb
hoe-seattlerb requires hoe >= 2.3.0
hoe >= 2.3.0 requires rubygems >= 1.3.1

I might have the specific dependency chain a bit off, but it’s enough to say that something required by rubygems-update itself requires a semi-recent RubyGems.

The solution is to update in stages. First update to 1.3.0, then update the rest of the way:

# gem install rubygems-update -v 1.3.0
Successfully installed rubygems-update-1.3.0
1 gem installed
# update_rubygems
Installing RubyGems 1.3.1
...
# gem update --system
Updating RubyGems
Updating rubygems-update
Successfully installed rubygems-update-1.3.5
:0:Warning: Gem::SourceIndex#search support for String patterns is deprecated
Updating RubyGems to 1.3.5
Installing RubyGems 1.3.5
RubyGems 1.3.5 installed

Capistrano Deployments from GitHub

Posted by: on Jul 27, 2009 in Blog | Tags: , | No Comments

Late last week I spent a chunk of time helping a client troubleshoot a deployment problem with Capistrano. For several weeks, I’ve been working on the site, deploying without any trouble, but when he tried to do it himself, it failed:

$ cap deploy
  * executing `deploy'
  * executing `deploy:update'
 ** transaction: start
  * executing `deploy:update_code'
    updating the cached checkout on all servers
  * executing (...long git command snipped...)
    servers: ["example.com"]
    [example.com] executing command
 ** [example.com :: err] Permission denied (publickey).
 ** [example.com :: err] fatal: The remote end hung up unexpectedly
    command finished
*** [deploy:update_code] rolling back

The problem was that I’d created a new user on his server to separate the production site from the staging site, and the staging user did not have a SSH key pair to access GitHub. It worked for me because I did have my SSH key on GitHub and a SSH agent in place that allowed authentication to be done through me instead of the server.

Capistrano’s error message in this case is not very helpful. If you think you’re having a similar problem, try cap shell and run a command, such as uptime. If that works, it’s not a permissions problem to your server, it’s probably from your server to GitHub. Either install a SSH agent or create a new key pair specifically for deployments.

Choose Your Words Wisely

Posted by: on Jul 21, 2009 in Blog | Tags: | One Comment

One of my recent projects is taking over development of a Rails site to prepare it for a private beta and ultimately a public launch. Aside from the usual learning curve of understanding a large existing code base, I’ve been struggling more than I should with some of the terms chosen by the original developers. It reminds me yet again that naming is hard, but also that names are important.

Names are important because they instantly put your brain in a certain context. If you choose a poor name, while you may not have any trouble with it, new developers or your customers might find themselves nearly unable to understand your intention. Simply using a different word can avoid this problem entirely.

Consider the environment in which names exist, too. One of the core models in this project is Action, which turns out to be a very unfortunate name in a Rails project. It is natural to want to use a local variable called action in code that uses this model, but that gets messy because a method that processes a request in a Controller is also called an action. This code “worked around” the problem by using actions instead, but being plural, it makes my brain want to treat it as an array, when it usually isn’t.

Another term used in a lot of the partials is node. Again, considering the context, this is an unfortunate choice because when you talk about the DOM as a tree, it is made up of nodes. There is now an extra moment of thought when I see this term: is this talking about the application’s node or a DOM node?

Names are meant to ease comprehension of a system by putting it in familiar terms. As complexity increases, so does the importance of good naming. Spend the extra time settling on good names. It’s much harder to change them later, when they have spread throughout your code and your team’s vocabulary.