Confluence and no end
Last Thursday, our on-premises Confluence turned out to have died without announcement. No more responses, although the apache wrapper (local proxy) and also the shipped Tomcat itself still ran thoroughly. The log files, although excessively detailed, if not bloated (as with any contemporary Java application stack), did not tell too much, actually they said nothing that gave any hint.
Since the system is multiply integrated (external database for, as it already turned out, quite good reasons, and also a Jira user server on a separately running Jira instance), so there could be many error sources.
But what actually helped in the end was to
mysqladmin -u root -p flush-hosts
and this really irritates me. I have been running MySQL based applications for quite a couple of years now, if not even decades. This event is totally new to me. With no further evidence, I have no choice but making assumptions on the underlying Java libraries, they seem to consist of a really amazing quality. Which, as always, is not about blaming Java, but the obviously totally unleashed deliberation of using whatever library comes across without further testing when it comes to building big applications from existing libraries.
Still I am open for a less suspicious and more evident explanation, feel free.