HaproxyRouteTcpRequirer documentation suggests multiple backend ports supported, when not

[andylshort]

Bug Description

The documentation for the construction parameters for HaproxyRouteTcpRequirer (and in other places) suggests:

port: The provider port.
backend_port: List of ports the service is listening on.

But backend_port is Optional[int], not a list.

What is the intended behaviour here? There are some instances where it might be very useful to actually have multiple backend ports, or for the port/backend port to be a mapping instead, so as to reduce the amount of relations required.

Impact

Low (minor issue or cosmetic problem)

Impact Rationale

No response

To Reproduce

See docs:

haproxy-operator/haproxy-operator/lib/charms/haproxy/v1/haproxy_route_tcp.py

Line 962 in 03f5598

class HaproxyRouteTcpRequirer(Object):

Environment

Latest version, any environment

Relevant log output

N/A.

Additional context

No response

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Thank you for reporting your feedback to us!

The internal ticket has been created: https://warthogs.atlassian.net/browse/ISD-5323.

This message was autogenerated

[Thanhphan1147]

Hi @andylshort, the intended behavior should be the latter, which is "One backend_port per relation". I'll update our docs to reflect that.

For multiple ports, I discussed this point with the team and we haven't yet seen ( or be able to think of ) any real use-cases where the same service is listening on more than one port, so we decided to go with on backend_port per relation.

Can you let me know a bit more about your use-case for multiple backend_port? I can bring it up as a discussion point with my team and eventually translate it to our team's product feedback board if necessary.

[skatsaounis]

Hi @Thanhphan1147

MAAS is an example of such service. We need the haproxy-route-tcp 4 times so we have to create 4 relations:

BP 5240 -> P 80 HTTP
BP 5443 -> P 443 HTTPS
BP 5271 -> P 5271 Temporal (runs inside the MAAS snap)
BP 5242 -> P 5242 Internal API

Ideally, we would like to have only one relation with a port_mapping dictionary or backend_ports, ports list where each list index matches the other. So that we have the different backends/frontends created in the HAProxy config.