In app-admin/logstash-bin-2.2.0, Gentoo's init script ran Logstash as root by default: /usr/portage/app-admin/logstash-bin/files/logstash.initd: LS_USER="${LS_USER:-root}" LS_GROUP="${LS_GROUP:-root}" In app-admin/logstash-bin-2.3.0, Logstash runs as its own user: /usr/portage/app-admin/logstash-bin/files/logstash.initd-r1: LS_USER=${LS_USER:-logstash} LS_GROUP=${LS_GROUP:-$LS_USER} This is significant if you've configured Logstash to read any files, e.g. syslog files which are only readable by root by default. While the problem was easy to spot and fix, it would have been nice to be warned of such a significant change by e.g. an einfo message in pkg_postinst.
It looks like this bug affects app-admin/logstash-bin-2.2.2-r1 as well, but I haven't tested that version.
Fixed in https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=5a4564496604d80cdffd7eccdb00e80ded5fe840 Thanks for reporting, if you have any comments, feel free to re-open.