GZip#

The 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.

Caution

When using the SSL/TLS protocol, compressed responses may be subject to BREACH attacks.

Configuration Example#

gzip            on;
gzip_min_length 1000;
gzip_proxied    expired no-cache no-store private auth;
gzip_types      text/plain application/xml;

The $gzip_ratio variable can be used to log the achieved compression ratio.

Directives#

gzip#

Syntax

gzip on | off;

Default

gzip off;

Context

http, server, location, if in location

Enables or disables gzipping of responses.

gzip_buffers#

Syntax

gzip_buffers number size;

Default

gzip_buffers 32 4k|16 8k;

Context

http, server, location

Sets the number and 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.

gzip_comp_level#

Syntax

gzip_comp_level level;

Default

gzip_comp_level 1;

Context

http, server, location

Sets a gzip compression level of a response. Acceptable values are in the range from 1 to 9.

gzip_disable#

Syntax

gzip_disable regex ...;

Default

Context

http, server, location

Disables gzipping of responses for requests with "User-Agent" header fields matching any of the specified regular expressions.

The special mask msie6 corresponds to the regular expression "MSIE [4-6].", but works faster. "MSIE 6.0; ... SV1" is excluded from this mask.

gzip_http_version#

Syntax

gzip_http_version 1.0 | 1.1;

Default

gzip_http_version 1.1;

Context

http, server, location

Sets the minimum HTTP version of a request required to compress a response.

gzip_min_length#

Syntax

gzip_min_length length;

Default

gzip_min_length 20;

Context

http, server, location

Sets the minimum length of a response that will be gzipped. The length is determined only from the "Content-Length" response header field.

gzip_proxied#

Syntax

gzip_proxied off | expired | no-cache | no-store | private | no_last_modified | no_etag | auth | any ...;

Default

gzip_proxied off;

Context

http, server, 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 "Via" request header field. The directive accepts multiple parameters:

off

disables compression for all proxied requests, ignoring other parameters;

expired

enables compression if a response header includes the "Expires" field with a value that disables caching;

no-cache

enables compression if a response header includes the "Cache-Control" field with the "no-cache" parameter;

no-store

enables compression if a response header includes the "Cache-Control" field with the "no-store" parameter;

private

enables compression if a response header includes the "Cache-Control" field with the "private" parameter;

no_last_modified

enables compression if a response header does not include the "Last-Modified" field;

no_etag

enables compression if a response header does not include the "ETag" field;

auth

enables compression if a request header includes the "Authorization" field;

any

enables compression for all proxied requests.

gzip_types#

Syntax

gzip_types mime-type ...;

Default

gzip_types text/html;

Context

http, server, location

Enables gzipping of responses for the specified MIME types in addition to "text/html". The special value "*" matches any MIME type. Responses with the "text/html" type are always compressed.

gzip_vary#

Syntax

gzip_vary on | off;

Default

gzip_vary off;

Context

http, server, location

Enables or disables inserting the "Vary: Accept-Encoding" response header field if the directives gzip, gzip_static or gunzip are active.

Built-in Variables#

$gzip_ratio#

achieved compression ratio, computed as the ratio between the original and compressed response sizes.