When exposing nbi with LoadBalancer service type, an empty ingress address is retrieved

[Nicolas Pochet]

When deploying OSM with NBI exposed with a LoadBalancer service type, it cannot find its ingress-addresses to send it to the other applications that need it (e.g. UI).

OSM is deployed with the following bundle: https://drive.google.com/open?id=1_6xJ0Z-NFDOEhP1K8qaopH8aeo2vrf_8

As K8s is deployed on top of OpenStack with Octavia, it makes sense to expose the OSM apps with a load-balancer instead of using Ingress.

We can see the following in the nbi-k8s-operator-0 logs:

kubectl logs nbi-k8s-operator-0 -n osm
...
tracer: ++ queue handler reactive/nbi.py:80:set_nbi_active
tracer: ++ queue handler reactive/nbi.py:90:send_config
2019-11-25 14:30:52 INFO juju-log Invoking reactive handler: reactive/nbi.py:80:set_nbi_active
2019-11-25 14:30:52 INFO juju-log Invoking reactive handler: reactive/nbi.py:90:send_config
2019-11-25 14:30:52 INFO juju-log status-set: maintenance: Sending NBI configuration
2019-11-25 14:30:54 INFO juju-log No ingress-addresses: {'bind-addresses': [{'macaddress': '', 'interfacename': '', 'addresses': []}]}
2019-11-25 14:30:54 INFO juju-log status-set: active: ready

[Nicolas Pochet (npochet)]

The log message saying that there's no ingress-addresses seems to come from https://git.launchpad.net/charm-osm-common/tree/lib/charms/osm/k8s.py#n8
The get_service_ip function calls network_get(endpoint, relation_id()) which will call network-get itself.
Looking at the juju status of the nbi-k8s app, it seems that juju does not know any address for this application:
juju status nbi-k8s
Model Controller Cloud/Region Version SLA Timestamp
osm foundation-k8s kubernetes_cloud 2.6.10 unsupported 14:48:15Z

SAAS Status Store URL
osm-vca active foundation-openstack admin/kubernetes.osm-vca

App Version Status Scale Charm Store Rev OS Address Notes
nbi-k8s active 1 nbi-k8s jujucharms 30 kubernetes

Unit Workload Agent Address Ports Message
nbi-k8s/0* active idle 10.1.3.33 9999/TCP ready

[Ian Booth (wallyworld)]

Juju can only know the ingress address once the service is available in the cluster. Each time this changes, the config-changed hook is run (moving forward we need another way to signal this to the charm other than the config-changed hook). The charm needs to be resilient enough to operate with incomplete information and wait till all information becomes available (which it eventually will).