From: Steven Hansen <runner@...>
Date: 2006-11-29T09:41:44+09:00
Subject: Re: Automating installation of gems on remote machine with Capistrano

Ezra Zygmuntowicz wrote:
>
> On Nov 27, 2006, at 1:56 PM, Steven Hansen wrote:
>
>>
>>
>> Greetings,
>>
>> I'm wondering if anyone has used Capistrano to automate the 
>> installation of gems on remote machines.
>>
>> The problem I'm having is that when you install a gem from the 
>> command line, at various stages it will prompt you for a 'Y' or 'N' 
>> answer.
>>
>> Let's say I have the following task and I want it to run on a remote 
>> machine:
>>
>> desc "Install rails"
>> task :install_rails do
>>  run "gem install rails"
>> end
>>
>> The task starts up and begins the installation, but then hangs after 
>> I get the 'Y' or 'N' prompt.
>>
>> Is there a way to just skip the prompt and specify 'Y' for everything?
>>
>> Regards,
>> Steven
>>
>
> Hey Steven-
>
>     Here is a capistrano plugin for installing gems remotely. This 
> supports slecting gem versions or letting it pick from the list itself 
> when it gets presented with a list of choices it will choose the 
> correct latest version based on architecture.
>
>     This is code adapted and extracted from the vmgen gem for 
> generating Xen instances.
>
>
> require 'capistrano'
> # Installs within Capistrano as the plugin _gem_.
> # Prefix all calls to the library with <tt>gem.</tt>
> # Manages installing gems and versioned gems.
> module Gem
>
>   # Default install command
>   #
>   # * doesn't install documentation
>   # * installs all required dependencies automatically.
>   #
>   GEM_INSTALL="gem install -y --no-rdoc"
>
>   # Upgrade the *gem* system to the latest version. Runs via *sudo*
>   def update_system
>     sudo "gem update --system"
>   end
>
>   # Updates all the installed gems to the latest version. Runs via 
> *sudo*.
>   # Don't use this command if any of the gems require a version 
> selection.
>   def upgrade
>     sudo "gem update --no-rdoc"
>   end
>
>   # Removes old versions of gems from installation area.
>   def cleanup
>     sudo "gem cleanup"
>   end
>
>   # Installs the gems detailed in +packages+, selecting version 
> +version+ if
>   # specified.
>   #
>   # +packages+ can be a single string or an array of strings.
>   #
>   def install(packages, version=nil)
>     sudo "#{GEM_INSTALL} #{if version then '-v '+version.to_s end} 
> #{packages.to_a.join(' ')}"
>   end
>
>   # Auto selects a gem from a list and installs it.
>   #
>   # *gem* has no mechanism on the command line of disambiguating 
> builds for
>   # different platforms, and instead asks the user. This method has 
> the necessary
>   # conversation to select the +version+ relevant to +platform+ (or 
> the one nearest
>   # the top of the list if you don't specify +version+).
>   def select(package, version=nil, platform='ruby')
>     selections={}
>     cmd="#{GEM_INSTALL} #{if version then '-v '+version.to_s end} 
> #{package}"
>     sudo cmd do |channel, stream, data|
>       data.each_line do | line |
>     case line
>     when /\s(\d+).*\(#{platform}\)/
>       if selections[channel[:host]].nil?
>         selections[channel[:host]]=$1.dup+"\n"
>         logger.info "Selecting #$&", "#{stream} :: #{channel[:host]}"
>       end
>     when /\s\d+\./
>       # Discard other selections from data stream
>     when /^>/
>       channel.send_data selections[channel[:host]]
>       logger.debug line, "#{stream} :: #{channel[:host]}"
>     else
>       logger.info line, "#{stream} :: #{channel[:host]}"
>     end
>       end
>     end
>   end
>
> end
>
> Capistrano.plugin :gem, Gem
>
>
> Cheers-
> -- Ezra Zygmuntowicz-- Lead Rails Evangelist
> -- ez@engineyard.com
> -- Engine Yard, Serious Rails Hosting
> -- (866) 518-YARD (9273)


Ezra,

Thank you! :-)

One question, is there a standard location to put capistrano plugins?  
The capistrano manual didn't mention anything about this so I suppose I 
could just stick it in my app's lib dir?


Kind Regards,
Steven