Using Postgres Schemas with Rails

migrations.rake

namespace :all_tenants do
  desc "Run migration for each tenant"
  task "db:migrate" => %w[environment db:load_config] do
    Tenant.find_each do |tenant|
      p "Running migration for tenant#{tenant.id}"
      tenant.scope_schema do
        ActiveRecord::Migration.verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] == "true" : true
        ActiveRecord::Migrator.migrate(ActiveRecord::Migrator.migrations_paths, ENV["VERSION"] ? ENV["VERSION"].to_i : nil) do |migration|
          ENV["SCOPE"].blank? || (ENV["SCOPE"] == migration.scope)
        end
      end
    end
    Rake::Task["db:schema:dump"].execute
  end
end

Rakefile

tasks = Rake.application.instance_variable_get '@tasks'
tasks.delete 'db:structure:dump'
namespace 'db' do
  namespace 'structure' do
    task :dump => [:environment, :load_config] do
      configuration = ActiveRecord::Tasks::DatabaseTasks.current_config
      filename = ENV['DB_STRUCTURE'] || File.join(Rails.root, "db", "structure.sql")
      ENV['PGHOST']     = configuration['host']          if configuration['host']
      ENV['PGPORT']     = configuration['port'].to_s     if configuration['port']
      ENV['PGPASSWORD'] = configuration['password'].to_s if configuration['password']
      ENV['PGUSER']     = configuration['username'].to_s if configuration['username']
      command = "pg_dump -i -s -x -O -f #{Shellwords.escape(filename)} --schema=public #{Shellwords.escape(configuration['database'])}"
      raise 'Error dumping database' unless Kernel.system(command)

      if ActiveRecord::Base.connection.supports_migrations?
        File.open(filename, "a") { |f| f << ActiveRecord::Base.connection.dump_schema_information }
      end
      # Dump ruby schema for reference
      Rake::Task["db:schema:dump"].invoke
    end
  end
end