Controller cfg for backend sg rule management

[nakamume]

Issue

#3265

Description

This PR introduces a controller config flag called ManageBackendSGRules. If the config is true (default) - controller behaves as before. If the config is false - controller wont manage the backend SG rules for both ingresses and services. Rules would still be created for controller managed frontend SGs for ingresses.

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the docs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes

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[nakamume]

@kishorj @M00nF1sh can I get some love ❤️ here?

[johngmyers]

This looks like it interacts with #3277. It's possible that #2277 addresses this.

The interaction between --enable-backend-security-group and --manage-backend-sg-rules is unclear and confusing. The documentation is not at all clear.

[nakamume]

This looks like it interacts with #3277. It's possible that #2277 addresses this.

Not sure how #2277 addresses this? Maybe wrong PR link? But #3277 seems to be going into the same direction except that it only covers the SG rules for ALBs(ingresses) and not NLBs (LB services).

The interaction between --enable-backend-security-group and --manage-backend-sg-rules is unclear and confusing.

Yes, I think it's a "bit". First is about weather a dedicated Security Group be created/used for backends and second is about rules for backend communication.

[johngmyers]

Why would one create a managed security group if one isn't going to create rules? Which of the combinatorics make sense for which use cases?

[nakamume]

I touched upon it in the issue desc #3265. Note that the feature BackendSGManagement is only for ingresses and doesn't cover the LB services.
With BackendSGManagement users can create (manually) or let controller create for them a single dedicated backend SG, this SG would be shared by all the ingresses in that cluster (ingresses managed by the LBC).
Then, they can either let the LBC control the rules for backends <- current/default behavior (unless users put an annotation not to do so) or manage the rules themselves <- disable rule management by the controller (feature added by this PR).

Even with manageBackendSG: false - controller creates the backend rules. BackendSG is just a single dedicated SG shared by all ingresses, without it controller creates a backend SG per ingress group.

[k8s-ci-robot]

PR needs rebase.

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This pull-request has been approved by: nakamume
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