I'm setting up a cluster of CouchDB 1.6.1 instances, with master/master
replication, behind a load balancer. All instances contain the same
data.
The load balancer will require a URL on each instance, to test and
decide whether the instance is "healthy" or not; instances deemed "not
health" are automatically removed from the load balancer. I would like
the test to be fairly comprehensive (in other words, don't return 200 OK
if the database is in fact not working well), but also I would like to
avoid tests that place unnecessary load on the DB. The test URL will be
accessed once every 5 ... 30 seconds.
I have a few options I could think of for now:
1. http://instance:5984/
Probably the lowest impact, but I'm not sure how much it reflects of the
DBs true health state.
2. http://instance:5984/_stats
Fairly low impact, I guess. Also, if _stats is working, that means at
least some components of the engine are okay.
3. http://instance:5984/mainDBname
We have one large DB and several smaller DBs. I could just point the
health check at the base URL for the main DB. I'm sure this is far more
representative of the actual health state of the DB. OTOH, I'm not sure
how much work is done by the DB to return that URL, and whether it would
add some unnecessary load.
Comments? Other ideas? Thanks.
--
Florin Andrei
http://florin.myip.org/
