Add option to toggle CRD installation

[matusf]

Description
Add helm value to helm chart to enable or disable CRD installation.

This would allow and simplify installing multiple instances of external-dns to one cluster. Also in multi-tenant clusters, where CRD installation is not allowed, this would be an great enabler. Default value is enabled, to not introduce any breaking changes, while allowing an override to disable the installation.

Fixes #4850

[k8s-ci-robot]

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[k8s-ci-robot]

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[matusf]

/assign @stevehipwell

[stevehipwell]

Thanks for the PR @matusf but that's not how CRDs work; you can't template a CRD in the crds folder, they're either in the chart or not. Please check out #4322 for the context around the decision to include the CRD in the Helm chart and I've added a comment to the original issue.

[matusf]

Hi, thanks, I know that crds ideally should be in the crds folder, but to template it I needed to put them inside the templates folder. It is done in this way in a bitnami chart of external-dns.

Regarding the --skip-crds flag. That does not really work for me because I have a helm chart that has multiple dependencies (external-dns being one of them) and I want to install crds from the other dependency. As far as I know, there is no way to set the --skip-crds to only one of my dependency. Only to whole chart.

I also read through the discussion in the #4322 PR, but I have not found any argument why it the crds should not be in the templates folder. As far as I understand, the discussion was about whether to include the crd in the chart or not.

[stevehipwell]

CRDs should be in the crds folder, that's the Helm idiom; putting them in templates isn't an option here. I also wouldn't take Bitnami charts as a source for patterns, this chart exists because I didn't want to use the Bitnami chart.

[matusf]

You are right, it is an idiom and should be followed if possible. However, I do not see other solution to this issue. There are many reputable charts that opted for this solution to solve the issue (because they have not found other solution). They are mentioned, in the issue you linked.

It seems like we are deciding between having a non idiomatic solution to an existing problem or not having a solution at all.

[stevehipwell]

@matusf I didn't want the CRD in the chart for this very reason, but given that you shouldn't use Helm for installing CRDs having the CRDs in the chart and expecting the use of --skip-crds is the compromise that was decided on. I'm not willing to move the CRDs out of their idiomatic location and into the templates dir just because others have done this.