Replace the activator access address from Pod IP to a more solid solution

[kerthcet]

What would you like to be added:

See discussion here: #498 (comment)

Why is this needed:

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[kerthcet]

/assign @X1aoZEOuO

[X1aoZEOuO]

Thanks! I'll take in deep about it. cc @kerthcet