feat: socket lb

[vvanglro]

Summary

This pr was put together while reviewing #2472, which reduced the complexity of the original code.

@graingert What do you think about this? If something is wrong, feel free to close it.

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.