[chef] Re: Re: Re: Re: A case for 'run once' recipes

["Brian O'Rourke" < >]

On Wed, Sep 23, 2009 at 5:10 PM, Tim Uckun < "> > wrote:

Idempotence is the prevailing paradigm amongst tools like chef but

personally I think there is a case for a "migrations" paradigm. IMHO
building and maintaining a server is not that different than building
and maintaining a database.  You start with the initial schema and it
evolves as time goes on.

The Rails-style database migrations you're referring to are an effort to effect idempotence for database schema changes. You migrate your schema once, and the changes that need to be applied are applied. When you run 'migrate' on a fully up-to-date schema, nothing happens because your migrations have already been run. Idempotent system changes are not at odds with systems evolving over time, nor are they at odds with processes being run only once (but you are responsible for keeping track of what's been run, at least at present).

--Brian P O'Rourke