bow

Automate your infrastructure provisioning and configuration with Rake.

About

Bow doesn't bring its own DSL to live, rather it uses regular Rake tasks instead.

It can be handy for you if:

• you need to configure a pure system of 2-5 VPSs;

• you don't want to build a complex infrastructure;

• you are already familiar with Rake and don't want to to learn Python;

Installation

Download and install bow with the following.

  gem install bow

Usage

First of all. If you're not familiar with Rake and Rake tasks, take a look at this pages: Rake docs and Rake home. It can be a good place to start from.

Project structure

The basic bow project consists of two files: Rakefile and targets.json.

Run bow init which will generate an example project structure to give you a basic understanding of how to write your own configuration.

Sometimes it can be convinient to put tasks to separate files into the rakelib folder. So Rake will automatically autoload them.

targets.json contains a list of hosts grouped in categories:

{
  "example_group1": [
    "192.168.50.27",
    "192.168.50.37"
  ],
  "example_group2": [
    "192.168.50.47",
    "192.168.50.57"
  ]
}

Rakefile is actually an ordinary Rakefile) which contains several tasks for provisioning packed in namespaces which are called by the name of the server groups from the targets.json file.

The main task of the group MUST always be called provision and can be bound to any number of additional tasks.

require 'bow/rake'

Rake.application.options.trace_rules = true

PROVISION_DIR = '/tmp/rake_provision'.freeze

namespace :web do
  task provision: :print_hello do
  end

  flow run: :once
  task :print_hello do
    sh 'echo "Hello from example group #1 server!"'
  end
end

namespace :example_group2 do
  task provision: :print_hello do
  end

  # Change enabled value to "false" to run the reverting task (:print_goodbye)
  flow enabled: true, revert_task: :print_goodbye
  task :print_hello do
    sh 'echo "Hello from example group #2 server!"'
  end

  task :print_goodbye do
    sh 'echo "Goodbye! The task at example group #2 is disabled!"'
  end
end

Commands

To check the availability of all configured hosts run:

  bow ping

To prepare soft on client needed for bow to run (Ruby and 2 gems: rake and bow) execute

  bow prepare

To apply configured provision run:

  bow apply

To explore more options and commands run:

  bow -h

Flow

Command flow from the upper example is a little extension added by the bow gem which allows you to controll the flow of the task. It consists of 3 options:

• run: :once or run: :always sets the condition on how many times to run the task;

• enabled: true or enabled: false wich takes a boolean value allows you to disable the task so it can be ommited or reverted (if a reverting task is given);

• revert: task_name wich defines a task that can revert changes done by the original task when the original task is disabled (by enabled: false option). Actually it's something similar to the down migration when dealing with ActiveRecord;

Run the example

To run the example locally this Vagrantfile can be used to create a testing environment.