feat: add new flag to allow configuring per pod FQDNs for service source.

[SerjKol80]

What does it do ?

Currently if you create FQDNs for K8S headless services, a service source will generate DNS record for the source. Also, in addition to that, if pods related to that service has a hostname configured, then FQDNs for each pod will also be created.
I.e. if you have service service-1 resulting into FQDN service-1.some.domain there will also be FQDNs like pod-1.service-1.some.domain be generated.

With this change

Fixes #5937

Motivation

I need to generate per pod FQDNs for pods created by Deployment.

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

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The committers listed above are authorized under a signed CLA.

• ✅ login: SerjKol80 / name: Sergey Kolosov (214b916)

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[k8s-ci-robot]

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[ivankatliarchuk]

What for? There is FQDN support https://github.com/kubernetes-sigs/external-dns/blob/master/docs/advanced/fqdn-templating.md. Is way more flexible

[SerjKol80]

What for? There is FQDN support https://github.com/kubernetes-sigs/external-dns/blob/master/docs/advanced/fqdn-templating.md. Is way more flexible

@ivankatliarchuk I'm not sure I got your point. how templating helps me to enable or disable per pods FQDNs for particular service. I.e. today "--source=service" flag will generate tons of DNS records (one per each pod created by StatefulSet). How can I disable it? Or another example: if I want such DNS records for K8s service backed by Deployments' pods. There is no way to do it today.
Unless I misunderstood something.

[ivankatliarchuk]

Closing, as feature supported with --fqdn-template=""

/close

[k8s-ci-robot]

@ivankatliarchuk: Closed this PR.

In response to this:

Closing, as feature supported with --fqdn-template=""

/close

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[SerjKol80]

@ivankatliarchuk Would you please explain deeper how --fqdn-template="" supports what I need? I axplain my thoughts deeper in issue's comment: #5937 (comment)

[SerjKol80]

/reopen

[k8s-ci-robot]

@SerjKol80: Reopened this PR.

In response to this:

/reopen

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[ivankatliarchuk]

#5938 (comment)

/hold

[ivankatliarchuk]

Please provide evidences that --fqdn-template does not support your use case.

[SerjKol80]

Please provide evidences that --fqdn-template does not support your use case.

@ivankatliarchuk I explained it in deep details in issue comment: #5937 (comment)