Added support to setup the containerPort property of the container webhook

[fjvela]

Description
Added support to setup the containerPort property of the container webhook

Fixes #4934

Checklist

• Unit tests updated
• End user documentation updated

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[stevehipwell]

@fjvela I'm not sure what the purpose of this PR is as the issue isn't clear about the intention. AFAIK the webhook port is fixed, I asked about this when it was added to the chart, so I don't see what this change does other than add a variable for a fixed value. Also you need to add the README comment to values.yaml and then run helm-docs to auto generate README.md.

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[fjvela]

hello @stevehipwell !

Sorry for my late response.

The idea is to allow the webhook application to execute on a port other than 8080.

The helm chart allows you to change the port of the SVC but doesn't allow you to execute your webhook application on a port other than 8080.

If you think it isn't useful, let me know to close the PR.

Best regards!

[stevehipwell]

It looks like #4756 was attempting to do something like this and it was closed.

Also to change the webhook port you'd also need to add the --webhook-provider-url flag or else ExternalDNS would still be looking for port 8888.

CC @mloiseleur.

[mloiseleur]

Yes, FTM, it's not designed to be flexible.
A webhook provider should listen on two ports: 8888 and 8080.
See https://kubernetes-sigs.github.io/external-dns/latest/docs/tutorials/webhook-provider/#implementation-requirements

It's on purpose: it helps to make migration from one provider to an other easier (among other things).