Pulsar

The easy Capistrano deploy and configuration manager.

Pulsar allows you to run Capistrano tasks via a separate repository where all your deploy configurations are stored. Once you have your own repository, you can gradually add configurations and recipes so that you never have to duplicate code again.

The way Pulsar works means that you can deploy without actually having the application on your local machine (and neither have all your application dependencies installed). This lets you integrate Pulsar with nearly any deploy strategy you can think of.

Some of the benefits of using Pulsar:

• No Capistrano configurations in the application code
• No need to have the application locally to deploy
• Every recipe can be shared between all applications
• Can easily be integrated with other tools
• Write the least possible code to deploy

DISCLAIMER: Understanding Capistrano is strongly suggested before using Pulsar.

Capistrano support

This version of Pulsar (version >= 1.0.0) only supports Capistrano v3. If you're looking for Capistrano v2 support you can use Pulsar version 0.3.5 but, take care, that version is not maintained anymore.

Installation

The most useful way of installing Pulsar is as a system gem:

$ gem install pulsar

This will install the pulsar command which will be used to for everything, from running Capistrano to listing your configurations.

The first thing you'll need to do is to create your own configuration repo:

$ pulsar install ~/Desktop/pulsar-conf

This will create a basic starting point for building your configuration repository. As soon as you're done configuring you should consider transforming this folder to a git repository.

You can have a look at how your repository should look like by browsing the Pulsar Conf Demo.

NOTE: Pulsar only supports git.

Configuration

This is an example repository configuration layout:

pulsar-conf/
  |── Gemfile
  ├── Gemfile.lock
  ├── apps
  │   ├── Capfile
  │   ├── deploy.rb
  │   └── my_application
  │       ├── Capfile
  │       ├── deploy.rb
  │       ├── production.rb
  │       └── staging.rb
  └── recipes
      ├── generic
      │   ├── maintenance_mode.rake
      │   ├── notify.rake
      │   └── utils.rake
      ├── rails
      │   ├── passenger.rake
      │   ├── repair_permissions.rake
      │   ├── symlink_configs.rake
      │   ├── unicorn.rake
      │   └── whenever.rake
      └── spree_1
          └── symlink_assets.rake

Pulsar uses these files to build Capistrano configurations on the fly, depending on how you invoke the pulsar command. Since Pulsar it's basically a Capistrano wrapper, the content of these files is plain old Capistrano syntax.

apps directory

This directory contains your application configurations. You'll have one directory per application.

• Capfile is the generic Capfile shared by all applications
• deploy.rb has configurations that are shared by all applications
• my_application/Capfile is the Capfile that will be used for this particular application
• my_application/deploy.rb includes configuration shared by every stage of the application
• my_application/staging.rb and my_application/production.rb files include stage configurations

recipes directory

This directory contains your recipes. You can create any number of directories to organize your recipes. In Capistrano v3 fashion, all the files are plain old rake tasks (make sure to name them with the .rake extension).

The recipes contained in this folder are always included in each stage for each application.

Another way to include your recipes is by using the Gemfile. Many gems already include custom recipes for Capistrano so you just need to require those. An example with Whenever:

#
# Inside Gemfile
#
gem 'whenever'

#
# Inside some Capfile (either generic or application specific)
#
require 'whenever/capistrano'

#
# Inside some .rb configuration file (either generic or application specific)
#
set :whenever_command, "bundle exec whenever"

Loading the repository

Once the repository is ready, you'll need to tell Pulsar where it is. The repository location can be specified either as a full git path or a GitHub repository path (i.e. gh-user/pulsar-conf).

Since Pulsar requires the repository for everything, there are multiple ways to store this information so that you don't have to type it every time. You can also use local repository, which is useful while developing your deployment.

You have three possibilities:

• -c command line option
• PULSAR_CONF_REPO environment variable
• ~/.pulsar/config configuration file

The fastest way is probably the .pulsar/config file inside your home directory:

#
# Inside ~/.pulsar/config
#
PULSAR_CONF_REPO="gh-user/pulsar-conf"

#
# Also supported
#
# PULSAR_CONF_REPO="git://github.com/gh-user/pulsar-conf.git"

Pulsar will read this file and set the environment variables properly.

If you don't want to add another file to your home directory you can export the variables yourself:

#
# Inside ~/.bash_profile or ~/.zshrc
#
export PULSAR_CONF_REPO="gh-user/pulsar-conf"

Usage

After the repository is ready, running Pulsar is straightforward. You can either list your applications or build a configuration and run Capistrano on it.

Deploy

Running the deploy command really means running Capistrano on a certain configuration.

To deploy my_application to production:

$ pulsar deploy my_application production

The above command will fetch the Pulsar configuration repository, run bundle install, combine the generic Capfile and deploy.rb files with the my_application specific ones and add specific production.rb stage configuration. At last it will run cap deploy on it.

Listing applications

Pulsar can fetch your configuration repository and list the application and stages you can run deploys on:

$ pulsar list

This will fetch the Pulsar configuration repository and list everything that's inside, like this:

my_application: production, staging
awesome_startup: dev, production, staging

Execute arbitrary Capistrano tasks

You can launch any Capistrano task via task command. You can also pass arguments in Rake style (i.e. via square brackets after task name)

$ pulsar task my_application staging mycustom:task[argumen1,argument2]

or via environment variables.

$ TASK_ARG1=arg1 TASK_ARG2=arg2 pulsar task my_application staging mycustom:task

Integrations

Pulsar is easy to integrate, you just need access to the configurations repository and the ability to run a command.

Right now there are no integrations for Pulsar v1 but there are some built for the old v0.3 version that can be used as an example.

Chat Bots

• https://gist.github.com/mtylty/5324075: a hubot script that runs Pulsar via the command line
• hubot-pulsar: a hubot plugin for integrating via Pulsar REST API
• lita-pulsar: a Lita plugin for integrating via the command line

Pulsar REST API service

Pulsar REST API is a service to provide a REST API for executing pulsar jobs.

Here is a real-life example of how you can integrate and simplify your Pulsar workflow.

About

Pulsar is funded and maintained by the Nebulab team.

We firmly believe in the power of open-source. Contact us if you like our work and you need help with your project design or development.