Name

ngx_http_unzstd_filter_module is a filter that decompresses responses with “Content-Encoding: zstd” for clients that do not support “zstd” (Zstandard compression) encoding method. The module will be useful when it is desirable to store data compressed to save space and reduce I/O costs.

Table of Content

• Name
• Table of Content
• Status
• Synopsis
• Installation
• Directives
  • unzstd
  • unzstd_force
  • unzstd_buffers
• Author
• License

Status

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

Synopsis

server {
    listen 127.0.0.1:8080;
    server_name localhost;

    location / {
        # enable zstd decompression for clients that do not support zstd compression
        unzstd on;

        proxy_pass http://foo.com;
    }
}

Installation

To use theses modules, configure your nginx branch with --add-module=/path/to/ngx_http_unzstd_filter_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.

Directives

unzstd

Syntax: unzstd on | off;

Default: unzstd off;

Context: http, server, location, when

Enables or disables decompression of zstd compressed responses for clients that lack zstd support. When built with ngx_condition_module, this directive can also be configured inside a when block.

unzstd_force

Syntax: unzstd_force on | off;

Default: unzstd_force off;

Context: http, server, location, when

When enabled, decompresses zstd responses without checking whether the client accepts zstd. Responses without Content-Encoding: zstd are not affected. When built with ngx_condition_module, this directive can also be configured inside a when block.

unzstd_buffers

Syntax: unzstd_buffers number size;

Default: unzstd_buffers 32 4k | 16 8k;

Context: http, server, location

Sets the number and size of buffers used to decompress a response. By default, the buffer size is equal to one memory page. This is either 4K or 8K, depending on a platform.

Author

Hanada im@hanada.info

This module is based on ngx_http_gunzip_module, one of nginx core modules and ngx_unbrotli, a nginx module for brotli decompression.

License

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