However, what happens when you want to write some tasks you can run on any remote server? What happens if you don’t have any servers and you want to build some dynamically and then run some remote tasks on them?

Well, I’ve been asking these questions and I found an answer that helped me out and thought I’d share it here.

Using the dependency system of rake and the lazy role evaluation of vlad along with the fact that it provides some very useful public class methods (so they are presumably safe, rather than hacking into the internals with send or the like) I wrote the following simple test script:

require 'rubygems'
require 'highline'
require 'vlad'
task :server_config do
  ssh_string = HighLine.new.ask 'Enter the SSH details of the server you want to connect to: '
  Rake::RemoteTask.role :server, ssh_string
end

desc 'Run stuff on a server'
remote_task :server, :roles => :server do
  run "echo 'hello i am a server'"
end
task :server => :server_config

What’s going on here is that I have a remote task using a role server which as of yet I haven’t defined. When I run rake server that runs the server task. The server task is dependent on the server_config task which sets up a role ‘server’ with the given string (ideally something like user@server.com). The remote task then executes, evaluating the value of the role, which is now set to the users input, and connects to the server you’ve set at run time. How awesome is that?

Of course, this is a contrived example, you could use a system to setup roles automatically from other things rather than pulling in user input but the lesson to take away here is that is is possible to use vlad tasks on dynamically defined targets easily.

My WiiFit exercise regime isn’t happening. I’m always busy with something it seems so I never get time. I’ve not actually used it for exercise in about 3 weeks now. Terrible I know. At least my body seems to be pretty happy hovering around 15.5st rather than still ramping up the pounds of fat

I’ve still been trying to write as much as possible and have managed to get Dru to start contributing more to protagonize which I am now a moderator of! So now I get to abuse my power for evil good. Woohoo!

I’ve been trying to keep the Bournemouth.rb Ruby Group up and running recently. So far we’re only small, but we’ve managed to run a few meetups so far. Currently we’re trying to find some projects to hack on together – if you have any ideas post them up on the Bournemouth.rb wiki. I’m quite enjoying this whole community lark. Let’s hope it lasts! If you are a rubyist in Bournemouth or if you’re just interested in the Ruby programming language and looking to get into it then try coming along, signup on the Bournemouth.rb mailing list for more info.

Turns out, you can.

On Drops there is a method ‘context=’ which gets set by the parser when it comes across a Drop object. From within the drop, all you need to do is access the @context variable and you’re away.

Why this isn’t advertised more is beyond me, or maybe I’m just an idiot and missed it, but I couldn’t see how to do this at all until I decided to sit down and essentially try and write it myself and delved into the code in Liquid that deals with processing variables. Turns out it’s already there and it works a charm. Nice for writing Drops that behave differently in different contexts, depending on register settings and the like.

Anyway, I thought it was useful, hope this helps someone else before they pull all their hair out.

function parse_git_branch {
  git branch --no-color 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/\1/'
}

function git-track {
  CURRENT_BRANCH=$(parse_git_branch)
  git-config branch.$CURRENT_BRANCH.remote $1
  git-config branch.$CURRENT_BRANCH.merge refs/heads/$CURRENT_BRANCH
}

With the above snippet in your bash conf (yes, I recognise the irony of editing a config file to give you a command to avoid editing a config file) you can just type:

git-track [remote name]

to track the branch you are currently in against the same branch in that remote. Simple.

require 'rubygems'
require 'hpricot'
doc = open('office2007.xls') { |f| Hpricot(f) }
csv = ''
doc.search('//row').each do |row|
(row/'cell/data').each do |data|
csv < < "\"#{data.to_plain_text}\"," if data
end
csv.chomp!(',')
csv << "\n"
end
File.open("output_file_name", 'w') {|f| f.write(csv) }

Hope someone finds this useful.

However, by perfectly good, I mean broken. It breaks because it doesn’t specifically require the correct versions of other gems but this you can fix. This is how I fixed it for my particular use case. I’m assuming you have a recent version of rubygems where you can use the gem method for specifying require’s gem versions.

Open up your old cap program, mine was here:
/usr/local/lib/ruby/gems/1.8/gems/capistrano-1.4.1/bin/cap

Before the “require ‘capistrano/cli’” line add the following:

gem 'net-ssh', '=1.0.10'
gem 'net-sftp', '=1.1.0'
gem 'capistrano', '=1.4.1'

I also edited my lib/tasks/capistrano.rake file to have the following code in it.

def cap(*parameters)
  begin
    require 'rubygems'
  rescue LoadError
    # no rubygems to load, so we fail silently
  end

  gem 'net-ssh', '=1.0.10'
  gem 'net-sftp', '=1.1.0'
  gem 'capistrano', '= 1.4.1'
  require 'capistrano/cli'

  Capistrano::CLI.new(parameters.map { |param| param.to_s }).execute!
end

Then I created a new symlink.

ln -s /usr/local/lib/ruby/gems/1.8/gems/capistrano-1.4.1/bin/cap /usr/local/bin/old_cap

Now I can run my old stuff and I have my old cap program as well.

Well, it was, and this is what I put in my unit_test_helper file:

# Clears active record configurations since we don't need them
# (and they cause query cache problems)
ActiveRecord::Base.configurations.clear

It’s sweet being able to just do:

require 'rubygems'
require 'tuxdroid'
tux = TuxDroid::Tux.new
tux.mouth  pen

Of course, you’ll need ruby-usb installed as well, which isn’t a gem as of yet so you’ll have to compile that manually.

I’m looking for other Rubyists in the Bournemouth area. There doesn’t seem to be a local Ruby User Group and so I’ve created a basic entry for one for Bournemouth at RubyHolic. Are there any other ruby guys or girls anywhere near me? I’d love to meet you.

I’m not very good at this whole organising groups thing, so be gentle when it comes to arranging a meet up

Since I didn’t see an option to add personal member details at rubyholic I’ll introduce myself here:

I’ve been using Ruby since 2+ years ago when I started using Rails. I work with it professionally as web developer and sysadmin for a local Bournemouth web design/development company called SonicIQ (SonicIQ are hiring by the way). I’m interested in all things Ruby and am currently working on a simple Ruby/SDL-based tile engine in my spare time among other various projects. I’m mostly a Linux guy and try to attend the local LUG with some kind of regularity but I also love my MacBook.

Now I’m going to cover the talks by James Cox, Damien Tanner, Ben Griffiths, Eleanor McHugh and the after-show party.

(…)