A rake task to automate deployment and database migration to Heroku

One of my major annoyances with Heroku is that the deploy does not automatically run any database migrations. Seriously?! So I ran into this tonight when I am trying to explain to a seasoned SA that while Heroku automatically will recompile your assets for you it will not do the migrations. A Google turned up this Stackoverflow question which in turn led to this gist. And I am excited to be trying it out.

Heroku: Scaling Dynos at night and in the morning

I needed a rake task to auto scale Dynos on Heroku; wind them down at night and wind them up in the morning. I found this helpful post on Stackoverflow. I made a few modifications and would up with this:

namespace :scale_dynos do
  require 'heroku-api'
  desc "scales up dynos"
  task :up do
    dyno_max = [6,0].include?(Time.now.wday) ? ENV['WEEKEND_DYNO_MAX'] : ENV['DYNO_MAX']
    heroku = Heroku::API.new(:api_key => ENV['HEROKU_API_KEY'])
    heroku.post_ps_scale(ENV['APP_NAME'], 'web', dyno_max.to_i)
  end

  desc "scales down dynos"
  task :down do
    dyno_min = ENV['DYNO_MIN']
    heroku = Heroku::API.new(:api_key =>  ENV['HEROKU_API_KEY'])
    heroku.post_ps_scale(ENV['APP_NAME'], 'web', dyno_min.to_i)
  end
end

It adjusts for the weekend to scale to a different level if you set the ENV varaible. Additionally here is how I set the Heroku config vars. The add command does them all at once but the remove goes through one by one, removes the VAR and restarts the app.

heroku config:add DYNO_MIN=1 DYNO_MAX=25 WEEKEND_DYNO_MAX=1 APP_NAME=<your app name> HEROKU_API_KEY=<your api key> -a <your app name>
heroku config:remove DYNO_MIN DYNO_MAX WEEKEND_DYNO_MAX APP_NAME HEROKU_API_KEY -a <your app name>

You will need the heroku-api gem. I also set the Gemfile entry to this:

gem 'heroku-api', :require => false

Since the rake task is called twice a day there was no need to load the gem into memory for the rest of the time.