Using a simple deployment process, downtime can occur. By running two identical production environments (Blue and Green), the risk of significant downtime is minimized. If you want to automate this process and minimize errors, use the Blue/Green deployment approach: http://docs.gopivotal.com/pivotalcf/devguide/deploy-apps/blue-green.html

This gem provides a Rake task to automate Blue/Green deployment to a Cloud Foundry installation. For deployments that include migrations, there is an option to deploy a Rack-based shutter app.

Currently, this gem requires Ruby 2.1.x or better. It is compatible with Cloud Foundy CLI versions 6.6 - 6.11.

Add this line to your application's Gemfile:

gem 'cloudfoundry_blue_green_deploy'

And then execute:

$ bundle install

Or download and install:

$ gem install cloudfoundry_blue_green_deploy

Make sure that all services that are specified in the manifest.yml file are created before running a first deployment.

1. Define the Blue and Green instances of your application(s) in your Cloud Foundry Manifest. (see rules in the next section)

2. Run:

    $ bundle exec rake cf:blue_green_deploy[web-app-name]
   

   Where "web-app-name" is the "name" attribute in your manifest.yml. The default color for first deployment is blue.

Your Cloud Foundry manifest file must comply with the following requirements:

• name: two application instances are required. One name ending with -green and another ending with -blue
• host: the url. One ending with -green and the other ending with -blue
• domain: required
• memory: optional, default will be used if omitted
• command: bundle exec rake cf:on_first_instance db:migrate && bundle exec rails s -p $PORT -e $RAILS_ENV
• services: Optional, only required if there are services that need to be bound

In this example: Our web application is known to Cloud Foundry as awesome-app with a database service known as memory-bank-db. Its URL is awesomeapp.cfapps.io.

---
applications:
- name: awesome-app-blue
  host: awesomeapp-blue
  domain: cfapps.io
  command: bundle exec rake cf:on_first_instance db:migrate && bundle exec rails s -p $PORT -e $RAILS_ENV
  services:
  - memory-bank-db

- name: awesome-app-green
  host: awesomeapp-green
  domain: cfapps.io
  command: bundle exec rake cf:on_first_instance db:migrate && bundle exec rails s -p $PORT -e $RAILS_ENV
  services:
  - memory-bank-db

And perform a blue/green deploy like this:

$ bundle exec rake cf:blue_green_deploy[awesome-app]

Non-trivial applications often require background processes to perform asynchronous jobs (e.g. sending email, importing data from external systems, etc.). If these applications' code are to stay in sync with the web application, they need Blue and Green treatment as well.

This Rake task natively supports worker application instances.

1. Define the Blue and Green instances of your application and workers in your Cloud Foundry Manifest. (see rules in the next section)

2. Run:

    $ bundle exec rake cf:blue_green_deploy[web-app-name,worker-name,another-worker-name]
   

• The web-app-name is the name attribute (without a color) detailed in your manifest.yml
• The worker-name and another-worker-name are name attributes for two separate worker apps as detailed in your manifest.yml
• Multiple worker apps can be specified as long as they comply with the blue/green deployment requirements in the manifest.yml.

For web application deployment (see requirements above)

For worker applications:

• name: Two application instances are required. One name ending with -green and another ending with -blue
• command: Required
• path: Relative to the current working directory
• services: Optional, only required if there are services that need to be bound

In this example:

• Our web application is known to Cloud Foundry as awesome-app.

• Its URL is awesomeapp.cfapps.io

• The app awesome-app has a database service known as memory-bank-db.

• We have a worker application named super-queue, whose database is known as key-vals-db.

    ---
    applications:
    - name: awesome-app-blue
      host: awesomeapp-blue
      domain: cfapps.io
      memory: 1GB
      path: .
      command: bundle exec rails s -p $PORT -e $RAILS_ENV
      services:
      - memory-bank-db
  
    - name: awesome-app-green
      host: awesomeapp-green
      domain: cfapps.io
      memory: 1GB
      path: .
      command: bundle exec rails s -p $PORT -e $RAILS_ENV
      services:
      - memory-bank-db
  
    - name: super-queue-blue
      command: bundle exec rails s -p $PORT -e $RAILS_ENV
      path: ../super-queue
      services:
      - key-vals-db
  
    - name: super-queue-green
      command: bundle exec rails s -p $PORT -e $RAILS_ENV
      path: ../super-queue
      services:
      - key-vals-db
  

And perform the blue/green deploy like this:

$ bundle exec rake cf:blue_green_deploy[awesome-app, super-queue]

For Blue and Green deployments that require a database migration this tool provides the ability to automatically shutter the app during the required downtime. To use this feature, create a shutter app and configure your manifest.yml.

1. Add the following to your manifest.yml. Note that the name must match the name of your production application and end in -shutter.

    - name: awesome-app-shutter
      command: bundle exec rackup config.ru -p $PORT -E $RACK_ENV
      path: shutter-app
   

2. Create a directory named shutter-app. In that directory:

• Create a Rack config config.ru

• Create a minimal Gemfile:

    source 'https://rubygems.org'
    ruby '2.1.2'
  
    gem 'rack'
  

• Create the Gemfile.lock by running Bundler in the shutter-app directory:

    $ bundle install
  

Our fail-fast philosophy. We recommend understanding deployment on Cloud Foundry before using this tool.