=encoding utf-8


=head1 Name

B<ngx_headers_more> - Set and clear input and output headers...more than "add"!

I<This module is not distributed with the Nginx source.> See L<the installation instructions>.


=head1 Version

This document describes headers-more-nginx-module L<v0.34|https://github.com/openresty/headers-more-nginx-module/tags> released on 17 July 2022.


=head1 Synopsis


     # set the Server output header
     more_set_headers 'Server: my-server';
    
     # set and clear output headers
     location /bar {
         more_set_headers 'X-MyHeader: blah' 'X-MyHeader2: foo';
         more_set_headers -t 'text/plain text/css' 'Content-Type: text/foo';
         more_set_headers -s '400 404 500 503' -s 413 'Foo: Bar';
         more_clear_headers 'Content-Type';
    
         # your proxy_pass/memcached_pass/or any other config goes here...
     }
    
     # set output headers
     location /type {
         more_set_headers 'Content-Type: text/plain';
         # ...
     }
    
     # set input headers
     location /foo {
         set $my_host 'my dog';
         more_set_input_headers 'Host: $my_host';
         more_set_input_headers -t 'text/plain' 'X-Foo: bah';
    
         # now $host and $http_host have their new values...
         # ...
     }
    
     # replace input header X-Foo *only* if it already exists
     more_set_input_headers -r 'X-Foo: howdy';


=head1 Description

This module allows you to add, set, or clear any output
or input header that you specify.

This is an enhanced version of the standard
L<headers|http://nginx.org/en/docs/http/ngx_http_headers_module.html> module because it provides more utilities like
resetting or clearing "builtin headers" like C<Content-Type>,
C<Content-Length>, and C<Server>.

It also allows you to specify an optional HTTP status code
criteria using the C<-s> option and an optional content
type criteria using the C<-t> option while modifying the
output headers with the L<more_set_headers> and
L<more_clear_headers> directives. For example,


     more_set_headers -s 404 -t 'text/html' 'X-Foo: Bar';

You can also specify multiple MIME types to filter out in a single C<-t> option.
For example,


    more_set_headers -t 'text/html text/plain' 'X-Foo: Bar';

Never use other parameters like C<charset=utf-8> in the C<-t> option values; they will not
work as you would expect.

Input headers can be modified as well. For example


     location /foo {
         more_set_input_headers 'Host: foo' 'User-Agent: faked';
         # now $host, $http_host, $user_agent, and
         #   $http_user_agent all have their new values.
     }

The option C<-t> is also available in the
L<more_set_input_headers> and
L<more_clear_input_headers> directives (for request header filtering) while the C<-s> option
is not allowed.

Unlike the standard L<headers|http://nginx.org/en/docs/http/ngx_http_headers_module.html> module, this module's directives will by
default apply to all the status codes, including C<4xx> and C<5xx>.




=head1 Directives




=head2 more_set_headers

B<syntax:> I<more_set_headers [-t E<lt>content-type listE<gt>]... [-s E<lt>status-code listE<gt>]... [-a] E<lt>new-headerE<gt>...>

B<default:> I<no>

B<context:> I<http, server, location, location if>

B<phase:> I<output-header-filter>

Replaces (if any) or adds (if not any) the specified output headers when the response status code matches the codes specified by the C<-s> option I<AND> the response content type matches the types specified by the C<-t> option.

If the "-a" option is specified, the specified output headers can be appended directly without clearing the old fields. The behavior of builtin headers such as "Content-Type", "Content-Length", "Server", etc. cannot be changed.

If either C<-s> or C<-t> is not specified or has an empty list value, then no match is required. Therefore, the following directive set the C<Server> output header to the custom value for I<any> status code and I<any> content type:


       more_set_headers    "Server: my_server";

Existing response headers with the same name are always overridden. If you want to add headers incrementally, use the standard L<add_header|http://nginx.org/en/docs/http/ngx_http_headers_module.html#add_header> directive instead.

A single directive can set/add multiple output headers. For example


       more_set_headers 'Foo: bar' 'Baz: bah';

Multiple occurrences of the options are allowed in a single directive. Their values will be merged together. For instance


       more_set_headers -s 404 -s '500 503' 'Foo: bar';

is equivalent to


       more_set_headers -s '404 500 503' 'Foo: bar';

The new header should be the one of the forms:


=over


=item 1.

C<Name: Value>

=item 2.

C<Name: >

=item 3.

C<Name>


=back

The last two effectively clear the value of the header C<Name>.

Nginx variables are allowed in header values. For example:


        set $my_var "dog";
        more_set_headers "Server: $my_var";

But variables won't work in header keys due to performance considerations.

Multiple set/clear header directives are allowed in a single location, and they're executed sequentially.

Directives inherited from an upper level scope (say, http block or server blocks) are executed before the directives in the location block.

Note that although C<more_set_headers> is allowed in I<location> if blocks, it is I<not> allowed in the I<server> if blocks, as in


       ?  # This is NOT allowed!
       ?  server {
       ?      if ($args ~ 'download') {
       ?          more_set_headers 'Foo: Bar';
       ?      }
       ?      ...
       ?  }

Behind the scene, use of this directive and its friend L<more_clear_headers> will (lazily) register an ouput header filter that modifies C<< r->headers_out >> the way you specify.




=head2 more_clear_headers

B<syntax:> I<more_clear_headers [-t E<lt>content-type listE<gt>]... [-s E<lt>status-code listE<gt>]... E<lt>new-headerE<gt>...>

B<default:> I<no>

B<context:> I<http, server, location, location if>

B<phase:> I<output-header-filter>

Clears the specified output headers.

In fact,


        more_clear_headers -s 404 -t 'text/plain' Foo Baz;

is exactly equivalent to


        more_set_headers -s 404 -t 'text/plain' "Foo: " "Baz: ";

or


        more_set_headers -s 404 -t 'text/plain' Foo Baz

See L<more_set_headers> for more details.

The wildcard character, C<*>, can also be used at the end of the header name to specify a pattern. For example, the following directive
effectively clears I<any> output headers starting by "C<X-Hidden->":


     more_clear_headers 'X-Hidden-*';

The C<*> wildcard support was first introduced in L<v0.09>.




=head2 more_set_input_headers

B<syntax:> I<more_set_input_headers [-r] [-t E<lt>content-type listE<gt>]... E<lt>new-headerE<gt>...>

B<default:> I<no>

B<context:> I<http, server, location, location if>

B<phase:> I<rewrite tail>

Very much like L<more_set_headers> except that it operates on input headers (or request headers) and it only supports the C<-t> option.

Note that using the C<-t> option in this directive means filtering by the C<Content-Type> I<request> header, rather than the response header.

Behind the scene, use of this directive and its friend L<more_clear_input_headers> will (lazily)
register a C<rewrite phase> handler that modifies C<< r->headers_in >> the way you specify. Note that it always run at the I<end> of
the C<rewrite> phase so that it runs I<after> the standard L<rewrite module|http://nginx.org/en/docs/http/ngx_http_rewrite_module.html>
and works in subrequests as well.

If the C<-r> option is specified, then the headers will be replaced to the new values I<only if> they already exist.




=head2 more_clear_input_headers

B<syntax:> I<more_clear_input_headers [-t E<lt>content-type listE<gt>]... E<lt>new-headerE<gt>...>

B<default:> I<no>

B<context:> I<http, server, location, location if>

B<phase:> I<rewrite tail>

Clears the specified input headers.

In fact,


        more_clear_input_headers -t 'text/plain' Foo Baz;

is exactly equivalent to


        more_set_input_headers -t 'text/plain' "Foo: " "Baz: ";

or


        more_set_input_headers -t 'text/plain' Foo Baz

To remove request headers "Foo" and "Baz" for all incoming requests regardless of the content type, we can write


        more_clear_input_headers "Foo" "Baz";

See L<more_set_input_headers> for more details.

The wildcard character, C<*>, can also be used at the end of the header name to specify a pattern. For example, the following directive
effectively clears I<any> input headers starting by "C<X-Hidden->":


         more_clear_input_headers 'X-Hidden-*';




=head1 Limitations


=over


=item *

Unlike the standard L<headers|http://nginx.org/en/docs/http/ngx_http_headers_module.html> module, this module does not automatically take care of the constraint among the C<Expires>, C<Cache-Control>, and C<Last-Modified> headers. You have to get them right yourself or use the L<headers|http://nginx.org/en/docs/http/ngx_http_headers_module.html> module together with this module.

=item *

You cannot remove the C<Connection> response header using this module because the C<Connection> response header is generated by the standard C<ngx_http_header_filter_module> in the Nginx core, whose output header filter runs always I<after> the filter of this module. The only way to actually remove the C<Connection> header is to patch the Nginx core, that is, editing the C function C<ngx_http_header_filter> in the C<src/http/ngx_http_header_filter_module.c> file.


=back




=head1 Installation

Grab the nginx source code from L<nginx.org|http://nginx.org/>, for example,
the version 1.17.8 (see L<nginx compatibility>), and then build the source with this module:


     wget 'http://nginx.org/download/nginx-1.17.8.tar.gz'
     tar -xzvf nginx-1.17.8.tar.gz
     cd nginx-1.17.8/
    
     # Here we assume you would install you nginx under /opt/nginx/.
     ./configure --prefix=/opt/nginx \
         --add-module=/path/to/headers-more-nginx-module
    
     make
     make install

Download the latest version of the release tarball of this module from L<headers-more-nginx-module file list|https://github.com/openresty/headers-more-nginx-module/tags>.

Starting from NGINX 1.9.11, you can also compile this module as a dynamic module, by using the C<--add-dynamic-module=PATH> option instead of C<--add-module=PATH> on the
C<./configure> command line above. And then you can explicitly load the module in your C<nginx.conf> via the L<load_module|http://nginx.org/en/docs/ngx_core_module.html#load_module>
directive, for example,


    load_module /path/to/modules/ngx_http_headers_more_filter_module.so;

Also, this module is included and enabled by default in the L<OpenResty bundle|http://openresty.org>.




=head1 Compatibility

The following versions of Nginx should work with this module:


=over


=item *

B<1.21.x>                      (last tested: 1.21.4)

=item *

B<1.19.x>                      (last tested: 1.19.9)

=item *

B<1.17.x>                      (last tested: 1.17.8)

=item *

B<1.16.x>

=item *

B<1.15.x>                      (last tested: 1.15.8)

=item *

B<1.14.x>

=item *

B<1.13.x>                      (last tested: 1.13.6)

=item *

B<1.12.x>

=item *

B<1.11.x>                      (last tested: 1.11.2)

=item *

B<1.10.x>

=item *

B<1.9.x>                       (last tested: 1.9.15)

=item *

B<1.8.x>

=item *

B<1.7.x>                       (last tested: 1.7.10)

=item *

B<1.6.x>                       (last tested: 1.6.2)

=item *

B<1.5.x>                       (last tested: 1.5.8)

=item *

B<1.4.x>                       (last tested: 1.4.4)

=item *

B<1.3.x>                       (last tested: 1.3.7)

=item *

B<1.2.x>                       (last tested: 1.2.9)

=item *

B<1.1.x>                       (last tested: 1.1.5)

=item *

B<1.0.x>                       (last tested: 1.0.11)

=item *

B<0.9.x>                       (last tested: 0.9.4)

=item *

B<0.8.x>                       (last tested: 0.8.54)

=item *

B<0.7.x E<gt>= 0.7.44>             (last tested: 0.7.68)


=back

Earlier versions of Nginx like 0.6.x and 0.5.x will I<not> work.

If you find that any particular version of Nginx above 0.7.44 does not work with this module, please consider L<reporting a bug>.




=head1 Community




=head2 English Mailing List

The L<openresty-en|https://groups.google.com/group/openresty-en> mailing list is for English speakers.




=head2 Chinese Mailing List

The L<openresty|https://groups.google.com/group/openresty> mailing list is for Chinese speakers.




=head1 Bugs and Patches

Please submit bug reports, wishlists, or patches by


=over


=item 1.

creating a ticket on the L<GitHub Issue Tracker|https://github.com/chaoslawful/lua-nginx-module/issues>,

=item 2.

or posting to the L<OpenResty community>.


=back




=head1 Source Repository

Available on github at L<openrestyE<sol>headers-more-nginx-module|https://github.com/openresty/headers-more-nginx-module>.




=head1 Changes

The changes of every release of this module can be obtained from the OpenResty bundle's change logs:

E<lt>http://openresty.org/#ChangesE<gt>




=head1 Test Suite

This module comes with a Perl-driven test suite. The L<test cases|https://github.com/openresty/headers-more-nginx-module/tree/master/t/> are
L<declarative|https://github.com/openresty/headers-more-nginx-module/blob/master/t/sanity.t> too. Thanks to the L<Test::Nginx|http://search.cpan.org/perldoc?Test::Nginx> module in the Perl world.

To run it on your side:


     $ PATH=/path/to/your/nginx-with-headers-more-module:$PATH prove -r t

To run the test suite with valgrind's memcheck, use the following commands:


     $ export PATH=/path/to/your/nginx-with-headers-more-module:$PATH
     $ TEST_NGINX_USE_VALGRIND=1 prove -r t

You need to terminate any Nginx processes before running the test suite if you have changed the Nginx server binary.

Because a single nginx server (by default, C<localhost:1984>) is used across all the test scripts (C<.t> files), it's meaningless to run the test suite in parallel by specifying C<-jN> when invoking the C<prove> utility.

Some parts of the test suite requires modules L<proxy|http://nginx.org/en/docs/http/ngx_http_proxy_module.html>, L<rewrite|http://nginx.org/en/docs/http/ngx_http_rewrite_module.html>, and L<echo|https://github.com/openresty/echo-nginx-module> to be enabled as well when building Nginx.




=head1 TODO


=over


=item *

Support variables in new headers' keys.


=back




=head1 Getting involved

You'll be very welcomed to submit patches to the L<author> or just ask for a commit bit to the L<source repository> on GitHub.




=head1 Authors


=over


=item *

Yichun "agentzh" Zhang (章亦春) I<E<lt>agentzh@gmail.comE<gt>>, OpenResty Inc.

=item *

Bernd Dorn ( E<lt>http://www.lovelysystems.com/E<gt> )


=back

This wiki page is also maintained by the author himself, and everybody is encouraged to improve this page as well.




=head1 Copyright & License

The code base is borrowed directly from the standard L<headers|http://nginx.org/en/docs/http/ngx_http_headers_module.html> module in Nginx 0.8.24. This part of code is copyrighted by Igor Sysoev.

Copyright (c) 2009-2017, Yichun "agentzh" Zhang (章亦春) E<lt>agentzh@gmail.comE<gt>, OpenResty Inc.

Copyright (c) 2010-2013, Bernd Dorn.

This module is licensed under the terms of the BSD license.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:


=over


=item *

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

=item *

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.


=back

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.




=head1 See Also


=over


=item *

The original thread on the Nginx mailing list that inspires this module's development: L<"A question about add_header replication"|http://forum.nginx.org/read.php?2,11206,11738>.

=item *

The orginal announcement thread on the Nginx mailing list: L<"The "headers_more" module: Set and clear output headers...more than 'add'!"|http://forum.nginx.org/read.php?2,23460>.

=item *

The original L<blog post|http://agentzh.blogspot.com/2009/11/headers-more-module-scripting-input-and.html> about this module's initial development.

=item *

The L<echo module|https://github.com/openresty/echo-nginx-module> for Nginx module's automated testing.

=item *

The standard L<headers|http://nginx.org/en/docs/http/ngx_http_headers_module.html> module.


=back



