Presently, CouchDB 2.0 logs only to stderr. I have opened a PR to switch this behaviour to log to the ./var/log/couchdb.log release-local file by default:
https://github.com/apache/couchdb/pull/435 This behaviour is easily overridden in the default.ini/local.ini files if desired. I'm not sure if this is wanted by all stakeholders, so I haven't merged it into master. Please let me know either here or in the PR your thoughts. My intent is to merge this change by lazy consensus.
