=encoding utf-8
=head1 NAME
ngx_http_gzip_module - Module ngx_http_gzip_module
=head1
The C<ngx_http_gzip_module> module is a filter
that compresses responses using the “gzip†method.
This often helps to reduce the size of transmitted data by half or even more.
=head1 Example Configuration
gzip on;
gzip_min_length 1000;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain application/xml;
The C<$gzip_ratio> variable can be used to log the
achieved compression ratio.
=head1 Directives
=head2 gzip
B<syntax:> gzip I<C<on> E<verbar> C<off>>
B<default:> I<off>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
B<context:> I<if in location>
Enables or disables gzipping of responses.
=head2 gzip_buffers
B<syntax:> gzip_buffers I<I<C<number>> I<C<size>>>
B<default:> I<32 4kE<verbar>16 8k>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Sets the I<C<number>> and I<C<size>> of buffers
used to compress a response.
By default, the buffer size is equal to one memory page.
This is either 4K or 8K, depending on a platform.
B<NOTE>
Until version 0.7.28, four 4K or 8K buffers were used by default.
=head2 gzip_comp_level
B<syntax:> gzip_comp_level I<I<C<level>>>
B<default:> I<1>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Sets a gzip compression I<C<level>> of a response.
Acceptable values are in the range from 1 to 9.
=head2 gzip_disable
B<syntax:> gzip_disable I<I<C<regex>> ...>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
This directive appeared in version 0.6.23.
Disables gzipping of responses for requests with
C<User-Agent> header fields matching
any of the specified regular expressions.
The special mask “C<msie6>†(0.7.12) corresponds to
the regular expression “C<MSIE [4-6]\.>â€, but works faster.
Starting from version 0.8.11, “C<MSIE 6.0; ... SV1>â€
is excluded from this mask.
=head2 gzip_min_length
B<syntax:> gzip_min_length I<I<C<length>>>
B<default:> I<20>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Sets the minimum length of a response that will be gzipped.
The length is determined only from the C<Content-Length>
response header field.
=head2 gzip_http_version
B<syntax:> gzip_http_version I<C<1.0> E<verbar> C<1.1>>
B<default:> I<1.1>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Sets the minimum HTTP version of a request required to compress a response.
=head2 gzip_proxied
B<syntax:> gzip_proxied I<
C<off> E<verbar>
C<expired> E<verbar>
C<no-cache> E<verbar>
C<no-store> E<verbar>
C<private> E<verbar>
C<no_last_modified> E<verbar>
C<no_etag> E<verbar>
C<auth> E<verbar>
C<any>
...>
B<default:> I<off>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Enables or disables gzipping of responses for proxied
requests depending on the request and response.
The fact that the request is proxied is determined by
the presence of the C<Via> request header field.
The directive accepts multiple parameters:
=over
=item C<off>
disables compression for all proxied requests,
ignoring other parameters;
=item C<expired>
enables compression if a response header includes the
C<Expires> field with a value that disables caching;
=item C<no-cache>
enables compression if a response header includes the
C<Cache-Control> field with the
“C<no-cache>†parameter;
=item C<no-store>
enables compression if a response header includes the
C<Cache-Control> field with the
“C<no-store>†parameter;
=item C<private>
enables compression if a response header includes the
C<Cache-Control> field with the
“C<private>†parameter;
=item C<no_last_modified>
enables compression if a response header does not include the
C<Last-Modified> field;
=item C<no_etag>
enables compression if a response header does not include the
C<ETag> field;
=item C<auth>
enables compression if a request header includes the
C<Authorization> field;
=item C<any>
enables compression for all proxied requests.
=back
=head2 gzip_types
B<syntax:> gzip_types I<I<C<mime-type>> ...>
B<default:> I<textE<sol>html>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Enables gzipping of responses for the specified MIME types in addition
to “C<textE<sol>html>â€.
The special value “C<*>†matches any MIME type (0.8.29).
Responses with the “C<textE<sol>html>†type are always compressed.
=head2 gzip_vary
B<syntax:> gzip_vary I<C<on> E<verbar> C<off>>
B<default:> I<off>
B<context:> I<http>
B<context:> I<server>
B<context:> I<location>
Enables or disables inserting the C<Vary: Accept-Encoding>
response header field if the directives
L</gzip>,
L<ngx_http_gzip_static_module>, or
L<ngx_http_gunzip_module>
are active.
=head1 Embedded Variables
=over
=item C<$gzip_ratio>
achieved compression ratio, computed as the ratio between the
original and compressed response sizes.
=back