Name

zstd-nginx-module - Nginx module for the Zstandard compression.

Table of Content

• Name
• Status
• Synopsis
• Installation
• Directives
  • ngx_http_zstd_filter_module
    • zstd_dict_file
    • zstd
    • zstd_comp_level
    • zstd_min_length
    • zstd_types
    • zstd_buffers
  • ngx_http_zstd_static_module
    • zstd_static
• Variables
  • ngx_http_zstd_filter_module
    • $zstd_ratio
• Author

Status

This Nginx module is currently considered experimental. Issues and PRs are welcome if you encounter any problems.

Synopsis

# specify the dictionary
zstd_dict_file /path/to/dict;

server {
    listen 127.0.0.1:8080;
    server_name localhost;

    location / {
        # enable zstd compression
        zstd on;
        zstd_min_length 256; # no less than 256 bytes
        zstd_comp_level 3; # set the level to 3

        proxy_pass http://foo.com;
    }
}

server {
    listen 127.0.0.1:8081;
    server_name localhost;

    location / {
        zstd_static on;
        root html;
    }
}

Installation

To use theses modules, configure your nginx branch with --add-module=/path/to/zstd-nginx-module. Several points should be taken care.

• You can set environment variables ZSTD_INC and ZSTD_LIB to specify the path to zstd.h and the path to zstd shared library represently.
• static library will be tried prior to dynamic library, since this Nginx module uses some advanced APIs where static linking is recommended.
• System's zstd bundle will be linked if ZSTD_INC and ZSTD_LIB are not specified.
• Both ngx_http_zstd_static_module and ngx_http_zstd_filter_module will be configured.

Directives

ngx_http_zstd_filter_module

The ngx_http_zstd_filter_module module is a filter that compresses responses using the "zstd" method. This often helps to reduce the size of transmitted data by half or even more.

zstd_dict_file

Syntax: zstd_dict_file /path/to/dict;
Default: -
Context: http

Specifies the external dictionary.

WARNING: Be careful! The content-coding registration only specifies a means to signal the use of the zstd format, and does not additionally specify any mechanism for advertising/negotiating/synchronizing the use of a specific dictionary between client and server. Use the zstd_dict_file only if you can insure that both ends (server and client) are capable of using the same dictionary (e.g. advertise with a HTTP header). See https://github.com/tokers/zstd-nginx-module/issues/2 for the details.

zstd

Syntax: zstd on | off;
Default: zstd off;
Context: http, server, location, if in location

Enables or disables zstd compression for response.

zstd_comp_level

Syntax: zstd_comp_level level;
Default: zstd_comp_level 1;
Context: http, server, location

Sets a zstd compression level of a response. Acceptable values are in the range from 1 to ZSTD_maxCLevel().

zstd_min_length

Syntax: zstd_min_length length;
Default: zstd_min_length 20;
Context: http, server, location

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

zstd_types

Syntax: zstd_types mime-type ...;
Default: zstd_types text/html;
Context: http, server, location

Enables ztd of responses for the specified MIME types in addition to "text/html". The special value "*" matches any MIME type.

zstd_buffers

Syntax: zstd_buffers number size;
Default: zstd_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.

ngx_http_zstd_static_module

The ngx_http_zstd_static_module module allows sending precompressed files with the ".zst" filename extension instead of regular files.

zstd_static

Syntax: zstd_static on | off | always;
Default: gzip_static off;
Context: http, server, location

Enables ("on") or disables ("off") checking the existence of precompressed files. The following directives are also taken into account: gzip_vary.

With the "always" value, "zsted" file is used in all cases, without checking if the client supports it.

Variables

ngx_http_zstd_filter_module

$zstd_ratio

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

Author

Alex Zhang (张超) zchao1995@gmail, UPYUN Inc.

License

This Nginx module is licensed under BSD 2-Clause License.