conn pool: use hostnames of endpoints as SNI values

[dmitriyilin]

Commit Message: conn pool: use hostnames of endpoints as SNI values Additional Description: optional support for usage of upstream cluster endpoints' hostnames as SNI values Risk Level: Low Testing: integration Docs Changes: added information about new mechanism of SNI derivation Release Notes: https://github.com/dmitriyilin/envoy/blob/b8e8a4537e537da66925f442cd5aeb45094cc3c9/changelogs/current.yaml#L377 Platform Specific Features: N/A Fixes #15839

[repokitteh-read-only[bot]]

Hi @dmitriyilin, welcome and thank you for your contribution.

We will try to review your Pull Request as quickly as possible.

In the meantime, please take a look at the contribution guidelines if you have not done so already.

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/34898 was opened by dmitriyilin.

see: more, trace.

[repokitteh-read-only[bot]]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/). envoyproxy/api-shepherds assignee is @abeyad CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

:cat:

Caused by: https://github.com/envoyproxy/envoy/pull/34898 was opened by dmitriyilin.

see: more, trace.

[dmitriyilin]

I see that "Publish and verify" check fails in other PRs as well. Is anything required from me?

[dmitriyilin]

Just realized that "auto_san_validation" functionality is not consistent with the new mechanism. I'll fix it.

[dmitriyilin]

@mattklein123 , @abeyad I've fixed SAN validation. Can you review the changes?

[abeyad]

FYI, I'll be OOO for a couple weeks, so if this PR has API changes again that need further review, you probably want to find another API reviewer, thanks!

[dmitriyilin]

@mattklein123 , can you help finding a new member of API shepherds for reviewing the change? Does @envoyproxy/api-shepherds referencing work?