Add default name to IngressClass and tidy SCC handling

[soneillf5]

Proposed changes

Fixes deletion bug, using the default name for the ingress class for deletion and creation.

Minor refactor to SCC resource handling.

*** UPDATED ***

I've removed the code that deletes the ingress class. This resource shouldn't be deleted when an IC is deleted, it should be removed when the operator is deleted.

Checklist

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• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto master
• I will ensure my PR is targeting the master branch and pulling from my branch from my own fork

[ciarams87]

Actually after testing it out, this approach may not work - deleting the default ingressClass (a global resource) on a single ingress controller deletion will lead to difficulty when we have several ICs sharing the same resource.

[lucacome]

I'm a little bit confused. What's the deletion bug?

[soneillf5]

@lucacome Sorry for the lack of description, the deletion bug is the following sequence:

• An IngressController is created
• 'controllers/prerequisites.go:18' checkPrerequisites is called before it's created
• this function creates an IngressClass if it doesn't exist. (L61)
• If the name of the IngressClass is not specified, it uses the default name 'nginx'
• A finaliser is added to CR resources, in this case an IngressController
• The IC is deleted
• In the reconcile loop, we see a finaliser needs to be addressed so 'finalizeNginxIngressController' is called
• This tries to delete the IngressClass but it fails as it can't find it an IngressClass with no name. (BUG HERE)
• The failed deletion causes the finaliser to exit with an error
• the reconcile loop ignores the error, leaving the finalizer
• the reconcile loop is Called again and fails to delete the resource ( hence the loop)

Essentially, the deletion code isn't add the default value for the IngressClass name that the addition code did.