Nginx Compression

nginx(8) is able to seamlessly compress data before sending over the wire. This reduces the amount of traffic, at the cost of computation time.

Unit Measurements

In nginx(8) configuration files, size and offset are measured in...

• bytes (no suffix)

• kilobytes (k or K suffix)

• megabytes (m or M suffix)

• gigabytes (g or G suffix)

To be clear, a size or offset without any suffix will be treated as a measurement in bytes.

Usage

Gzip

The gzip directive belongs in the http block and takes either on or off.

For many deployments, this is all the configuration needed to get 'good enough' results.

http {
  gzip on;
}

Gzip_Buffers

Gzip_Comp_Level

Gzip_Disable

The gzip_disable directive disables compression based on the user agent. It takes a regex that should match user agents for which compression is disabled.

http {
  # Disable compression for Internet Explorer up to version 6
  gzip_disable "MSIE [1-6]\.";

  # A special value that is equivalent to the regex "MSIE [4-6]\." but faster
  gzip_disable "msie6";
}

Gzip_Http_Version

The gzip_http_version directive disables compression based on the version of HTTP used.

The default is:

http {
  gzip_http_version 1.1
}

This is because HTTP 1.0 does not allow for simulatenously keepalive and compression.

Gzip_Min_Length

The gzip_min_length directive sets a threshold based on a response's "Content-Length" header. Below this threshold, data is sent uncompressed.

http {
  gzip_min_length 1024;
}

Gzip_Proxied

The gzip_proxied directive causes data to be compressed for proxied connections.

By default this is not done because the proxy should cache that data itself. That proxy already is a solution for reducing traffic. The computation time of (1) nginx(8) compressing the data and (2) the proxy decompressing the data scales poorly.

The directive takes one or more of the following values:

Gzip_Type

Gzip_Vary

The gzip_vary directive causes both compressed and uncompressed data to be cached. This is only useful if some data won't be compressed.

http {
  gzip_vary on;
}

See also

Module ngx_http_gzip_module documentation

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