Add preferred address type field to ListenerClass

[nightkr]

Description

See stackabletech/listener-operator#139. In short, it allows users to specify whether they want to prefer exposing IP addresses or hostnames.

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[nightkr]

Implementation PR is up: stackabletech/listener-operator#233

[sbernauer]

CRD change LGTM

[sbernauer]

CRD change LGTM

[nightkr]

Voting comment

[lfrancke]

Approved during planning meeting. Go ahead!

[lfrancke]

So...the typical questions...
Do we have docs and if so could you link them? And as this is user visible I guess a release note snippet would be good?
But it's not breaking? Do users need to take action?

[nightkr]

The docs are in the listener-operator PR (https://github.com/stackabletech/listener-operator/pull/233/files#diff-865c09909a15c5d0a5ec7ec8dc2e2458dcd8f8843c0405876210a9d96c7a6781).

But it's not breaking? Do users need to take action?

See #885 (comment), it changes the default for NodePort listeners from IP to DNS, which requires the nodes to have DNS-resolvable hostnames.

[lfrancke]

Okay, thanks. So this should really go into the release notes then I guess. Could you please write a snippet?

[nightkr]

Release notes snippet:

Listeners can now be configured to use either IP addresses or DNS hostnames.

BREAKING: All ListenerClasses now default to using DNS hostnames, previously NodePort ListenerClasses (such as external-unstable) would use IP addresses. Hence, all Nodes must now have resolvable hostnames, or the NodePort ListenerClasses must be configured to set .spec.preferredAddressType: IP.