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From: Damien Katz <damienkatz@gmail.com>
To: couchdb-dev@incubator.apache.org,
 couchdb-user@incubator.apache.org
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Subject: server configuration stuff
Date: Thu, 10 Apr 2008 16:02:18 -0400

Currently that CouchDB handles configuration stuff is to reads in it's  
configuration setting at startup time the couch.ini file, and then  
feeds those settings as startup arguments to the various child servers  
processes. This requires that to change a setting you must restart to  
take effect.

This is fine for now, but we can do better. I'd like to enhance this  
by providing a configuration module that allows for configuration  
settings to be changed at runtime, and automatically have those  
changes take effect without requiring a server restart.

The way I was thinking it would work, at startup the server  
configuration module sucks up the settings from the couch.ini, then  
the child processes are started normally, but without startup  
arguments. The child processes then query the runtime module at  
startup, or whenever, to get their configuration data.

It should be possible for the core modules to subscribe notifications  
of configuration updates. In Erlang, this is typically done by the  
modules registering a callback function. So when a configuration  
setting is updated, it would get invoked with the changed settings as  
arguments.

And when a configuration setting is changed at runtime, the module  
should write the new setting back to the couch.ini file. And it should  
be able to handle updates to settings, etc, and ideally still preserve  
all previous formatting and comments.

So, some questions. What do people think of this in general? Or should  
we be using the apache conf format instead of ini? Maybe we should use  
json?

One things I'd like to see is that configuration stuff be editable in  
a text editor. However, I might be dissuaded to start using a CouchDB  
database to store everything but the most critical startup information.

Thoughts please.