Lookup of kubernetes.default.svc may not return FQDN.

[GrahamDumpleton]

Describe the bug

In session manager config startup it uses:

CLUSTER_DOMAIN = socket.getaddrinfo("kubernetes.default.svc", 0, flags=socket.AI_CANONNAME)[0][3]
CLUSTER_DOMAIN = CLUSTER_DOMAIN.replace("kubernetes.default.svc.", "")

to work out the internal cluster domain, eg., cluster.local.

In more recent versions of Loft virtual clusters, this is returning kubernetes alone, rather than kubernetes.svc.cluster.local. Thus is not possible to calculate correct cluster domain and CLUSTER_DOMAIN is being set to kubernetes.

The calculation should check if returned name actually starts with kubernetes.default.svc and if it doesn't then override it to cluster.local.

To cope with any other strange unexpected values, it should also be possible to manually override clusterDomain via the Educates data values when deploying it.

Additional information

No response

[GrahamDumpleton]

Perhaps should use:

>>> socket.gethostbyaddr(os.environ["KUBERNETES_SERVICE_HOST"])
('kubernetes.default.svc.cluster.local', [], ['10.96.0.1'])

instead.

For now keep looking up kubernetes.default.svc but possible change later if need be.

[GrahamDumpleton]

In future should perhaps add clusterDomain variable to Educates configuration so this can be overridden.