All server operating systems and application software are setup and updated using automated configuration tools, such as Puppet, Chef, or AWS Cloud Formation.  (TBD)

Related 

• Resource Runbook
• Equivalent Staging and Production Environments

See also

• Immutable Server (MartinFowler.com)
• Configuration Management (ContinuousDelivery.com)

Tools

• AWS Cloud Formation
• Chef
• Puppet