We recently upgraded one of our clusters to 7.9.3 (from 6.8.12), and I'm now seeing frequent, but intermittent, proxy errors while in stack monitoring. For instance here is a screenshot of a minute or so in the monitoring overview:
Sample httpd log from a request:
[Mon Nov 02 18:23:03.907127 2020] [proxy_http:error] [pid 112] (104)Connection reset by peer: [client ...:55770] AH01102: error reading status line from remote server kibanamon:5601, referer: https://.../kibanamon/app/monitoring
[Mon Nov 02 18:23:03.907160 2020] [proxy:error] [pid 112] [client ...:55770] AH00898: Error reading from remote server returned by /kibanamon/api/monitoring/v1/alert/5Hic1QrdQTmZwzbEPNUFLw/status, referer:https://.../kibanamon/app/monitoring ... - kretzke
[02/Nov/2020:18:23:03 +0000] "POST /kibanamon/api/monitoring/v1/alert/5Hic1QrdQTmZwzbEPNUFLw/status HTTP/1.1"502 506 "https://.../kibanamon/app/monitoring" "Mozilla/5.0 (Macintosh;Intel Mac OS X 10.14; rv:82.0) Gecko/20100101 Firefox/82.0"0
There are no related messages in the kibana log with logging.verbose:true
Kibana and httpd (2.4.6) are running in Docker containers on the same host, under docker-compose. We didn't see any issues like this with Kibana 6.8.12, even on the same host through the same httpd proxy.
httpd is running a basic reverse proxy config:
ProxyPass /kibanamon http://kibanamon:5601
ProxyPassReverse /kibanamon http://kibanamon:5601
<location /kibanamon>
AuthType Shibboleth
[... auth settings]
</location>
Seems like a bug somewhere in the monitoring server, but I'm reaching out here first in case anyone has some ideas; maybe we need to make some changes to the proxy settings?