Client IP preservation in Armada loadbalancer

Watson IoT Platform has to complete migration work to Armada-based Kubernetes cluster by June 2018 in at least one multi-tenant environment. That environment has at least one large customer already and will potentially have more shortly.

Part of the existing MQTT messaging support used by external customers, operators and developers is an ability to record the IP address of the client device/application. For example, client IP address is used in customer-visible connection logs and as part of internal connection management.

Currently Armada loadbalancer doesn't support this functionality. As described in https://kubernetes.io/docs/tasks/access-application-cluster/create-external-load-balancer/#preserving-the-client-source-ip, the client IP address is obscured and may cause a second hop to another node, which has performance implications under load.

Watson IoT Platform needs to have this support available by the end of February 2018 in order to meet our hard dates. Corresponding issue opened for Armada team is here: https://github.ibm.com/alchemy-containers/armada-network/issues/169.

Not having this functionality would prevent operators, both IBMers and customers, from performing problem determination related to platform connectivity. Multiple customers currently use this functionality, at least one of them is large.