✅ All required contributors have signed the F5 CLA for this PR. Thank you!
_{Posted by the CLA Assistant Lite bot.}

I have hereby read the F5 CLA and agree to its terms

Inheritance control for add_header and add_trailer.

Headers filter: ?

New directives add_header_inherit and add_trailer_inherit control how
headers and trailers are inherited from the previous level.

The value "off" disables inheritance. The value "on" (default) triggers

s/value/parameter/? also to avoid confusing with header/trailer array "values"

the previous behavior when the values from the previous level are inherited
only if no values are set at the current level.

Just for the record, both can be expressed with add_header "" (empty value).
So essentially this adds a syntax sugar value by the "merge" mode.

The value "merge" enables
merging the values from the previous level into the current level values.

The inheritance control modes are themselves inherited in a standard way.
Thus "add_header_inherit merge" specified at the top level will enable
the merge inheritance mode for all the levels below.

Personally, it may be visually challenging to read text not broken in paragraphs,
I'd add some empty lines for better visibility experience.

Headers filter: inheritance control for add_header and add_trailer.

The new directives add_header_inherit and add_trailer_inherit allow
to alter inheritance rules for the values specified in the add_header
and add_trailer directives in a convenient way.

The "merge" parameter appends the values from the previous level to
the current level values.

The "off" parameter cancels inheritance of the values from the previous
configuration level, similar to add_header "" (2194e75bb).

The "on" parameter restores the default behaviour to inherit values from
the previous level only if there are no directives on the current level.

The inheritance rules themselves are inherited in a standard way.  Thus,
for example, "add_header_inherit merge;" specified at the top level will
be inherited in all nested levels recursively unless redefined below.

The diff technically looks good, though I'd still try to implement this in the existing directives,
similar to proxy_redirect off;. This would also match expires off; in the same module.

The diff technically looks good, though I'd still try to implement this in the existing directives, similar to proxy_redirect off;. This would also match expires off; in the same module.

Discussed this in person. My points:

• embedding inheritance control into add_header will make it hard to implement similar behavior for other directives (proxy_set_header for example)
• it's not clear how embedded inheritance control will itself be inherited, while a separate directive is inherited in a standard way

Inheritance control for add_header and add_trailer.

Headers filter: ?

New directives add_header_inherit and add_trailer_inherit control how
headers and trailers are inherited from the previous level.
The value "off" disables inheritance. The value "on" (default) triggers

s/value/parameter/? also to avoid confusing with header/trailer array "values"

the previous behavior when the values from the previous level are inherited
only if no values are set at the current level.

Just for the record, both can be expressed with add_header "" (empty value). So essentially this adds a syntax sugar value by the "merge" mode.

The value "merge" enables
merging the values from the previous level into the current level values.
The inheritance control modes are themselves inherited in a standard way.
Thus "add_header_inherit merge" specified at the top level will enable
the merge inheritance mode for all the levels below.

Personally, it may be visually challenging to read text not broken in paragraphs, I'd add some empty lines for better visibility experience.

Headers filter: inheritance control for add_header and add_trailer.

The new directives add_header_inherit and add_trailer_inherit allow
to alter inheritance rules for the values specified in the add_header
and add_trailer directives in a convenient way.

The "merge" parameter appends the values from the previous level to
the current level values.

The "off" parameter cancels inheritance of the values from the previous
configuration level, similar to add_header "" (2194e75bb).

The "on" parameter restores the default behaviour to inherit values from
the previous level only if there are no directives on the current level.

The inheritance rules themselves are inherited in a standard way.  Thus,
for example, "add_header_inherit merge;" specified at the top level will
be inherited in all nested levels recursively unless redefined below.

Thanks, modified a bit and applied.