Capistrano 3 PostgreSQL backup task for Rails

deploy.rb

# ...
# config/deploy.rb, config/deploy/production.rb etc.
# contents omitted
###

# example: add backup task prior to deploy
namespace :deploy do
  before :deploy, "db:dump"
end

pgbackup.rake

# The task assumes you have figaro application.yml config in Capistrano shared folder
# https://github.com/laserlemon/figaro

require 'sshkit'

namespace :db do
  desc "Backup your PostgreSQL database to ~/"
  task :dump do
    on roles(:db) do
      @dbconf = dbconfig
      dbuser = @dbconf['username']
      dbname = @dbconf['database']
      dbhost = @dbconf['host']

      # feel free to add required flags for pg_dump
      # http://www.postgresql.org/docs/9.4/static/app-pgdump.html
      within '~/' do
        execute :pg_dump,
                "-W -U #{dbuser} -h #{dbhost} --format=plain --quote-all-identifiers",
                "#{dbname} > \"pims_backup_$(date +%F_%R).sql\"",
                interaction_handler: {
                  'Password: ' => "#{dbpass}\n"
                }
      end
    end
  end

  # extract Rails database config
  def dbconfig
    YAML::load(
      capture :cat, "#{current_path}/config/database.yml"
    )[fetch(:rails_env)]
  end

  # extract password from figaro shared config file
  def dbpass
    YAML::load(
      capture :cat, "#{shared_path}/config/application.yml"
    )['DATABASE_PASSWORD']
  end

end