Drop database of Rails application from Ruby script, outside of application - ruby

Question

I need to run 'rake db:drop' console command from ruby script (outside of Rails app). Generally it looks simple:
system("cd /my/path && rake db:drop")
But the problem is I'm under rvm hell, and when I'm doing cd /my/path it doesn't load correct gemset and environment, that's why as result I have
Could not find activesupport-3.1.12 in any of the sources
Run `bundle install` to install missing gems
Additionally, I have open connections problem, as Rails application is running.
How it could be done?
(my global task is to close existing connections to the database (we may have some, as I need to drop running rails app database), drop it, and then recreate again)
Thank you!

Answer 1

To kill active connections, I use this in a rake task. That should take care of one problem.
task :kill_postgres_connections => :environment do
db_name = "#{File.basename(Rails.root)}_#{Rails.env}"
sh = <<EOF
ps xa \
| grep postgres: \
| grep #{db_name} \
| grep -v grep \
| awk '{print $1}' \
| xargs kill
EOF
puts `#{sh}`
end
task "db:drop" => :kill_postgres_connections

Answer 2

To drop PostgreSQL db in Rails 4 you can also patch ActiveRecord drop method. Based on https://www.krautcomputing.com/blog/2014/01/10/how-to-drop-your-postgres-database-with-rails-4/
# config/initializers/postgresql_database_tasks.rb
module ActiveRecord
module Tasks
class PostgreSQLDatabaseTasks
def drop
establish_master_connection
connection.select_all "select pg_terminate_backend(pg_stat_activity.pid) from pg_stat_activity where datname='#{configuration['database']}' AND state='idle';"
connection.drop_database configuration['database']
end
end
end
end