Question

I want to do auto scaling using knife command line tool. My main goal is to set up master servers and then scale out the instances as per to load generation on the master servers. I have gone through this example.

Here, i can successfully create the entire stack on single server and also can create on multiple servers(by following that example).

Now my scenario is, I have one web app at one instance and db at another instance, and I am scale out the database instance due to heavy load on database instance but how do my web app will know that another database is created and use that database instance?

I am using opscode chef which gives the flexibility to manage instances. I want to know how and where to write configuration like the above scenario? and if any good reference anyone know will be appreciated.

Answer 1

Take a look at the application and database cookbooks, they have recipes that will set up a database config file for you (the java recipe for instance)

Once chef has configured this file you would need to reload that config file in your app or reboot it. Doing that would be up to you, depending on if you wanted to write a chef cookbook do do it or just watch for changes in your app.