Question

I am developing a Rails v2.3 app. with MySQL v5.1 database on a Ubuntu machine.

I know the commands to start, stop Nginx and MySQL on command line.

But now, I need to have the following process defined in one of my rake task of my Rails app.:

stop Nginx --> stop(shut down) MySQL --> ... --> start MySQL --> start Nginx

Which means all these need to be defined in ruby script in a rake task of my Rails app.

I am not sure how to make ruby code run the above process(execute the commands) in my rake task?

Answer 1

Check out Ruby’s Kernel module (it’s built in). Using backticks, you can run the commands to stop/start nginx and MySQL, and even check their exit codes to make sure they executed properly (If your stop/start scripts support exit codes).

Example:

# In your Rakefile
namespace :servers do
  task :stop do
    nginx_stop_output = `service nginx stop`
    if $?.exitstatus != 0
      # handle shutdown failure
    end

    mysql_stop_output = `service mysql stop`
    if $?.exitstatus != 0
      # handle shutdown failure
    end
  end

  task :start do
    nginx_start_output = `service nginx start`
    if $?.exitstatus != 0
      # handle startup failure
    end

    mysql_start_output = `service mysql start`
    if $?.exitstatus != 0
      # handle startup failure
    end
  end
end

Substitute in your own stop/start commands in the backticks.

You can then run these tasks with rake servers:stop and rake servers:start.