It may be usefull if Your claster has about 1-10 boxes, and tools like Chef, Puppet, Capistrano are too complex and proprietary for Your needs. It's very easy, there are only a 3 concept - Box, Cluster and Service.
Usage:
- package installation, dependencies, versioning
- process management, start/stop services
- deplyment
It's designed to be used with Virtual File System, Virtual Operation System and Rake, but it's not required, You can use other tools also. For testing purposes it uses Vagrant to test in a local Virtual Machine. If you're going to use Vagrant, you need to install VirtualBox
- Box - a PC with remote access.
- Service - some abstract thing (a package, running process, app, ...) that operates on 1..n boxes. It can perform install/update/start/stop/.. operations and request other services to perform things it needs.
- Deployment Scheme - defines how services are distributed among boxes.
Let's suppose that we want to deploy our App on a cluster of 3 boxes using the following scheme. Tags are used to define connections (N to M, althouth in example below it's 1 to 1) between Boxes and Services.
Deployment scheme defined via box tags (in config) and service tags, see below.
Boxes are defined in config:
handy_scheme:
'web1.app.com': ['web']
'web2.app.com': ['web']
'db.app.com': ['db']
Dependencies are defined by calling another services, it's easy to use and understand and allows high flexibility in configuration.
And, it's 'smart', in sample below the App::deploy method is smart ennought to figure out that it needs the Ruby and MySQL Services and it will call for them to apply before itself.
You can specify that the package should be applied only once (see :apply_once), and use versioning (see :version) - change the version and it will be reapplied.
It supports iterative development and can figure out what services are missing and needs to be applied, You don't have to write all the config at once, do it by small steps, adding one package after another.
Below are our Services:
class Services::Ruby < Service
tag :web
version 4
def install
# it will be called only once, it will be called next time only if You change the version
apply_once :install do |box|
logger.info "installing :#{service_name}"
box.fake_bash "apt-get install ruby"
end
end
end
class Services::Thin < Service
tag :web
def restart
logger.info "restarting :#{service_name}"
boxes.each{|box| box.fake_bash 'thin restart'}
end
end
class Services::MySql < Service
tag :db
def started
logger.info "ensuring mysql is running"
box.fake_bash 'mysql start' unless box.fake_bash('ps -A') =~ /mysql/
end
end
class Services::App < Service
tag :web
def install
services.ruby.install
apply_once :install do |box|
logger.info "installing :#{service_name}"
box.fake_bash "cd #{config.app_path} && git clone app"
end
end
def update
install
logger.info "updating :#{service_name}"
boxes.each{|box| box.fake_bash "cd #{config.app_path} && git pull app"}
end
def deploy
update
logger.info "deploying :#{service_name}"
services.my_sql.started
services.thin.restart
end
end
desc 'deploy to cluster'
task :deploy do
cluster.services.app.deploy
end
Note: You don't have install services before deployment, the App::deploy will resolve all dependencies automatically and fully configure all boxes from clean state - it will install packages, ensure all needed services are running and only then will start deployment.
Now, type:
$ rake deploy
You'll se something like this:
installing :ruby
=> bash: 'apt-get install ruby'
installing :app
=> bash: 'cd /tmp/cm_example_app && git clone app'
updating :app
=> bash: 'cd /tmp/cm_example_app && git pull app'
deploying :app
ensuring mysql is running
=> bash: 'ps -A'
=> bash: 'mysql start'
restarting :thin
=> bash: 'thin restart'
Deploy one more time, notice now there's no installation of Ruby and App:
updating :app
=> bash: 'cd /tmp/cm_example_app && git pull app'
deploying :app
ensuring mysql is running
=> bash: 'ps -A'
=> bash: 'mysql start'
restarting :thin
=> bash: 'thin restart'
$ gem install cluster_management
Clone cluster_management and go to example folder, there are full example. You can do the following:
$ bundle install
$ vagrant init # and wait for the image to be downloaded
$ vagrant up # this will power on the VM
$ rake deploy
installing :ruby to 10.11.12.13
deleting old version
building
configuring
updating environment
installing :app
updating :app
deploying :app
And voilĂ ! It's done!
You can also see 'real' configuration I use to manage the http://ruby-lang.info site, my_cluster.
Please feel free to submit bugs and proposals to the issue tab above, or contact me directly.