v2beta2 HPA w/prometheus query: 404 logs & <unknown>

[zalando-incubator]

v2beta2 HPA w/prometheus query: 404 logs &

from kube-metrics-adapter.

[RRAlex]

Uhm, code 18, seems like the Deployment & HPA's prometheus path might have not matched during testing (or some other magic), but it works now... 🐙

[RRAlex]

So it seems prometheus 2.18.1 wants the path prefix /prometheus for queries via /api/v1/query but setting it like this seems to ignore the /prometheus part, (still getting 404...):

metric-config.external.prometheus-query.prometheus/prometheus-server: http://prometheus.kube-system-monitoring.svc.cluster.local:9090/prometheus

EDIT:
The running process
/kube-metrics-adapter --prometheus-server=http://prometheus.kube-system-monitoring.svc.cluster.local:9090/prometheus --skipper-ingress-metrics --aws-external-metrics

The tcpdump from prometheus:

.I..y.z&5x\@..E..vu.@.@.............#...=..#.......|......A....ur.POST./api/v1/query.HTTP/1.1..Host:.prometheus.kube-system-monitoring.svc.cluster.local:9090..User-Agent:.Go-http-client/1.1..Content-Length:.102..Content-Type:.application/x-www-form-urlencoded..Accept-Encoding:.gzip....query=rabbitmq_queue_messages_ready%7Bqueue%3D%22task_priority_apiworker%22%7D&time=1590074409.0026362
z&5x\@.I..y...E.....@.@...........#....#....?..............u.7A...HTTP/1.1.404.Not.Found..Content-Type:.text/plain;.charset=utf-8..X-Content-Type-Options:.nosniff..Date:.Thu,.21.May.2020.15:20:09.GMT..Content-Length:.19....404.page.not.found.

Not sure why it's not getting /prometheus/api/v1/query...
Is it possible the path is stripped and there is no flag to point to a specific prometheus path, as defined by --web.external-url=http://example.com/prometheus' for example?