Different environments configuration on Google AppEngine

My favorite approach is to store them all in datastore and having only one master record in it with all the different properties and making a good use of the memcache. By doing that you don't need to have different configuration files or polluting your code with different configuration settings. Instead you can deploy and change this values from an administrative form that you will have to create in order to update this master record.

Also if you are storing tokens and secret keys then you are aware of the fact that is definitely not a good idea to have them in the web.xml or anywhere else in the code, but rather having it per application on something more secure, like datastore.

Once you have that, then you can have one global function that will retrieve properties by name and if you want to get the Google Analytics ID from anywhere in your app you should use it by having something like this:

getProperty('googleAnalyticsID') 

where this global getProperty() function will try to find this value with these steps:

• Check if it exist in memcache and return
• If not in memcache, update memcache from master entity from datastore and return
• If not in datastore create an entity with a default values, update memcache and return

Of course there are different approaches on how to retrieve data from that Model but the idea is the same: Store in one record and use the memcache.

You must have separate app ids for your production/staging/qa envs. This must be hardcorded into your web.xml (or you have a script of some sort that updates your web.xml)

After that you can code in your settings based on appid. I assume there's a java equivalent to this: https://developers.google.com/appengine/docs/python/appidentity/functions#get_application_id

You could put it in the datastore if they're settings that change dynamically, but if they are static to the environment, it doesn't make sense to keep fetching from datastore.