[chef] Re: "Cluster" Management

[Daniel DeLeo < >]

What you’re describing is a distributed leader election problem. If I was 
you, I’d manually manage a tag to pick the node that runs db setup and 
migrations. If the leader leaves the cluster (hardware failure, etc.), then 
tag a different node in the cluster with knife tag or something. If that ever 
becomes a burden on your team, then you need to run zookeeper or similar to 
get a really reliable leader election system that automatically handles 
systems going down, race conditions, etc.  

--  
Daniel DeLeo


On Thursday, April 10, 2014 at 8:47 AM, Stewart, Curtis wrote:

> We’re running a deployment of 3 rails app servers, and we only need one to 
> run the database setup.  
>  
> What’s the best solution for allowing Chef to determine which app should 
> run the db:setup?  
>  
> Is it safe to run a search for ‘role:app’, then only run db:setup if 
> current node is first node? We can even sort the search response to make 
> sure it’s always the same ordered response.  
>  
> I’d love to hear your suggestions!  
>  
> Thanks,
> Curtis