This was a short demo following a talk given at viennarb about vagrant by cypher on Thursday the 18th of July 2013 at sektor 5
I demonstrated how to create an incredibly simple distributed logger using DRuby and just as easily test it on multiple VMs using vagrant.
Init your boxes
The Vagrant is a vagrant init file which creates a server machine where you will run the server.rb file. You will need to change the constant at the top to point at the box name that you have downloaded. For example if you run
vagrant box add precise64 https://dl.dropbox.com/u/14292474/vagrantboxes/precise64-ruby-1.9.3-p194.box
you would have to change the constant to BOX = "precise64"
Run your boxes
To run vagrant you just need to run vagrant up
This will import your box and instantiate 1 server VM and 3 client VMs
You can change the client VM count by instead running CLIENT_COUNT=10 vagrant up
Run the drb server
SSH into your server machine vagrant ssh server run cd /vagrant && ruby server.rb and you should have your drb server running on 33.33.33.100:3030. The IP address was chosen in the Vagrantfile.
Log with the simple client
In your clients you can now run ruby simple_server.rb from the /vagrant directory which will print out a hello world message to the server machine's log file. (On the server or host machine you can run tail -f /vagrant/dev.log to see a stream of the log)
Install the client gem in your computer
on the host machine (your machine, not a VM) cd into the drb_logger_client directory and rake install (you may have to run bundle install as well). This will make your gem available to your client machines (sometimes I have had permission issues in my guests writing a new gem)
Install client gem on guest client machines
SSH into each of client via vagrant ssh cli_2 which would ssh into the second client box
After this you would need to cd /vagrant which will take you to the directory of the Vagrantfile on the host machine mounted in the client machine (vagrant does this by default)
Run gem install drb_logger_client/pkg/drb_logger_client-0.0.1.gem which will install the client gem on your client.
Install rails
in each of the client machines run cp -rf /vagrant/rails_app ~ to copy the rails app to your home directory. This again helps when rails trys create files on the host operating system without proper permissions.
gem install bundler && rbenv rehash && cd ~/rails_app && bundle install && bundle exec rails s
This may fail and if it does, it is because I am stupid and forgot to ask for no database drivers to be installed when I created the rails app or because you don't have a c compiler installed in you client so I recommend this
sudo apt-get -y install build-essential sqlite3 libsqlite3-dev
The only thing I have done to the rails app is to change the default logger in rails_app/config/environments/development.rb and I added a simple controller, action and route to that controller and action.
If you had errors and installed the packages above, you should be able to run
gem install bundler && rbenv rehash && cd ~/rails_app && bundle install && bundle exec rails s
again and your rails apps will be running.
Make it LOG!
In the Vagrantfile we forwarded the default rails port 3000 on our client machines to 4001-400(number of client instances) on our host (your main operating system)
Now you can visit in your normal browser http://localhost:4001 or http://localhost:4002 and if you are still tailing that log, you will see an OHAI message and the IP address of the machine that you hit.
I hope you aren't saying this. Once you do it and play around a little bit, this will make a ton of sense. Pretty much, vagrant always will mount the directory you ran vagrant up from on /vagrant in your guest boxes. That way you have access to your dynamic dev environment in that folder. The permissions thing is what makes everything complicated :(
I don't know how great this works on Windows. Good luck and I will probably not be able to debug any problems with that
Besides that, I will do my best to make this work and make sense to you