Update annotations.md with Classic Load Balancer warning

[Ramneek-kalra]

Added a warning about creating Classic Load Balancers and best practices (specially for Normal or EKS Auto Mode). As tested internally with a customer, and found this gap.

Issue

There's no mentioning about "Classic Load Balancer" use-case as many customers do are interested to continue using it.

Description

When replicated, below are the steps:

• Created EKS Cluster/AutoMode Cluster
• Created sample App + Namespace & Service with "NodePort" Type [Didn't create any ELB]
• Edited the Service YAML manually using "kubectl edit svc <> -n <>" and changed the type to "LoadBalancer" and it created CLB on ELB Console

The same can't be done when a service is created via manifest using Type "LoadBalancer" as it will ask for "service.beta.kubernetes.io/aws-load-balancer-subnets" and it will make controller behave as NLB identification and no more CLB can be created, instead it will create NLB.

Changes made

• Added a note/warning for CLB Creation

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

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Ramneek-kalra
Once this PR has been reviewed and has the lgtm label, please assign shuqz for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Ramneek-kalra / name: Ramneek Kalra (7e1cae3)

[k8s-ci-robot]

Welcome @Ramneek-kalra!

It looks like this is your first PR to kubernetes-sigs/aws-load-balancer-controller 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes-sigs/aws-load-balancer-controller has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. 😃

[k8s-ci-robot]

Hi @Ramneek-kalra. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.