dvara provides a connection pooling proxy for MongoDB. For more information look at the associated blog post: http://blog.parse.com/2014/06/23/dvara/.
To build from source you'll need Go. Fetch code:
go get github.com/intercom/dvara/cmd/dvara
Install the app
go install github.com/intercom/dvara/cmd/dvara
Run the proxy, assuming the mongodb is already running
dvara -addrs=$HOST:$PORT where host and port is location of mongo db instance
Library documentation: https://godoc.org/github.com/facebook/dvara