By default, incoming network traffic for websockets comes through these network
hops:
Internet -> LoadBalancer -> kube-proxy -> nginx-ingress-controller -> nginz -> cannon
In order to have graceful draining of websockets when something gets restarted (as implemented in #2416 ), as it is not easily possible to implement the graceful draining on nginx-ingress-controller or nginz by itself, with this PR there is now
a configuration option to get the following network hops:
Internet -> separate LoadBalancer for cannon only -> kube-proxy -> [nginz->cannon (2 containers in the same pod)]
More context:
https://wearezeta.atlassian.net/wiki/spaces/PS/pages/585564424/How+to+gracefully+drain+cannon+but+not+so+slowly
FUTUREWORK: this introduces some nginz config duplication; some way to refactor this (e.g. by moving charts/{cannon, nginz}/* to charts/wire-server/ in a backwards-compatible way) would allow to reduce this duplication.
Co-authored-by: jschaul <[email protected]>
