How to send a trigger to Puppet?

Is there anyway to send a trigger to Puppet to perform a series to tasks ?

The application is served by Apache httpd. Every once in a while developers make changes to the product which in turn requires us to restart Apache. However, I cannot figure out how to send a request to Puppet which in turn will restart Apache.

Basically, this is more of a asynchronous request compared to a "serial" or synchronous flow of Puppet run that executes every 30 minutes.

Any thoughts on this ?

Solution

Remember that puppet is not a task manager. puppet is a state manager.

It does not start or restart httpd; rather, it ensures that httpd is running.
It does not upload files, it verifies that files are installed and up-to-date.

The distinction is important.

That said ...

Is puppet also managing the changes being made by the developers?

If so, then you should be able to create a puppet rule

exec { httpdrestart :
    command => "/sbin/service httpd restart",
    refreshonly => true,
}

and then attach to whatever puppet rule is managing your developers' changes

file { '/var/www/html/mywebproject.html':
  ensure => present,
  source => 'puppet:///modules/mymodule/mywebproject.html',
  notify => Exec["httpdrestart"]
}

that after this file is installed/updated/changed, httpd needs to be restarted.

If you just expect puppet to restart httpd simple because you asked it to, then you either need to use a program like ansible which is more of an actual task manager, or use some kind of inotify thing to see that a certain file has been changed, so httpd must be restarted.

(caveat -- but I know nothing about inotify beyond the name.)