Creating a Mysql user within a Rails controller action - mysql

Question

Working on an app that wil be used by admin only to create multiple instances of another app.
In other words, app A will be used to create clones of app B on server and create all the configurations needed to run that cloned app on a subdomain new_clone.domain.com.
Managed to clone the app, created the apache config file, unicorn server settings file too. Managed to run rake db:create; db:migrate but I did this with the root user of mysql.
At the point where I clone the app, I generate a database.yml file for the new cloned app that has at this moment username and password set as root, but I woould like to have a different user for each cloned app.
The app A has a model called Subdomain, in the subdomains_controller.rb at the create action I do all the things, clone, generate config files, running rake tasks, etc... and also in this create action I need to create a new Mysql user with privileges for a specific database.
What I have tried so far, can't say I did much, I tried to run the mysql command within controller create action:
def create
if #subdomain.save
....
system "mysql -u root -p root; create database new_database;..."
....
else
....
end
end
but this puts my create action on hold until I type in the password, and even if I'll find a way to go over it I am not sure the rest of mysql commands will work. Probably there is a better way to add a Mysql user with one command line without going into mysql console.
Thank you.

Answer 1

As far as I understood, your create method runs under Rails app with root mysql user.
Then you can simply execute mysql commands via AR adapter:
# Create DB
ActiveRecord::Base.connection.execute("CREATE DATABASE IF NOT EXISTS \
`#{ActiveRecord::Base.sanitize(db_name)}` CHARACTER SET = `utf8` \
COLLATE = `utf8_general_ci`")
# Create User
ActiveRecord::Base.connection.execute("REPLACE INTO mysql.user \
(Host, User, Password) VALUES(\"localhost\", \
\"#{ActiveRecord::Base.sanitize(db_user)}\", \
PASSWORD(\"#{ActiveRecord::Base.sanitize(db_password)}\"))")
# Grant access
ActiveRecord::Base.connection.execute("GRANT ALL PRIVILEGES ON \
`#{ActiveRecord::Base.sanitize(db_name)}`.* TO \
`#{ActiveRecord::Base.sanitize(db_user)}`")
# Apply
ActiveRecord::Base.connection.execute("FLUSH PRIVILEGES")

Answer 2

Thanks to Yuriy's answer I got it working in a shorter way:
def create_mysql_user
#db_name = "#{#subdomain.name}_domain_production"
#db_user = "#{#subdomain.name}_user"
#db_password = "#{#subdomain.name}domain_password"
ActiveRecord::Base.connection.execute("GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, ALTER,
INDEX ON `#{#db_name}`.* TO #{ActiveRecord::Base.sanitize(#db_user)}#localhost
IDENTIFIED BY #{ActiveRecord::Base.sanitize(#db_password)};")
# Apply
ActiveRecord::Base.connection.execute("FLUSH PRIVILEGES")
end