[Feature request] Add configs to ignore server Cache-Control: max-age and Expires

[Hiroaki Nakamura]

Hi all,

I would like to add configs to ignore server Cache-Control: max-age and Expires.
In my use case, I would like to let origin server administrators to
use just Cache-Control: s-maxage
to control whether the contents are cacheable.

I am planning to create a CDN service and I would like to simplify the
rule for contents to be cached
because I would like to reduce the time to support users (the origin
server administrators).

I created a patch
https://github.com/apache/trafficserver/compare/master...hnakamur:add_config_ignore_server_cc_max_age_and_expires?expand=1

This patch adds two configs below:

.. ts:cv:: CONFIG proxy.config.http.cache.ignore_expires INT 0
   :reloadable:
   :overridable:

   When enabled (``1``), Traffic Server ignores any ``Expires``
   headers from the server. This technically violates the HTTP RFC,
   but simplifies the operation of web site administrators to control whether
   or not contents are cached.
   With combination with ``proxy.config.http.cache.required_headers = 2`` and
   ``proxy.config.http.cache.ignore_server_cc_max_age = 1``, only the value of
   ``Cache-Control: s-maxage`` is checked to determine the content is cacheable.

.. ts:cv:: CONFIG proxy.config.http.cache.ignore_server_cc_max_age INT 0
   :reloadable:
   :overridable:

   When enabled (``1``), Traffic Server ignores any ``Cache-Control:
   max-age`` headers from the server. This technically violates the HTTP RFC,
   but simplifies the operation of web site administrators to control whether
   or not contents are cached.
   With combination with ``proxy.config.http.cache.required_headers = 2`` and
   ``proxy.config.http.cache.ignore_expires = 1``, only the value of
   ``Cache-Control: s-maxage`` is checked to determine the content is cacheable.

Can I send this patch as a pull request?

Best regards,
Hiroaki