While the configuration systems we explored in this chapter share a fair number of similarities, they differ a lot in the way code is executed on the client nodes:
- With Puppet, a Puppet agent registers with the Puppet master and opens a communication channel to retrieve commands. This process is repeated periodically, normally every 30 minutes.
30 minutes isn't fast. You can, of course, configure a lower value for the time interval required for the next run. At any rate, Puppet essentially uses a pull model. Clients must check in to know whether changes are available.
- Ansible pushes changes over SSH when desired. This is a push model.
- Salt uses a push model, but with a different implementation. It employs a ZeroMQ messaging server that the clients connect to and listen for notifications about changes. This works a bit...
