Compression/Decompression in Nginx

Introduction

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- compression saves bandwidth but has extra cpu overhead

- by default, nginx compresses data before sending to client

- nginx doesn't double compress data (e.g response from a proxied server)

- to enable comression on proxied request, use `gzip_proxied`

- compression directives can be included in any of the ff contexts:

    a. http

    b. server

    c. location

Enabling Compression

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enables compression for MIME type text/html	gzip on;
compresses data with other MIME types	gzip_types text/plain application/xml; gzip on;
specify minimum length of response to compress (default is 20 bytes)	gzip_min_length 1000;
enables compression on proxied requests	gzip_proxied no-cache no-store private expired auth;   # - compresses responses whose "Cache-Control" header field has   #   any of the following:   #    a. no-cache   #    b. no-store   #    c. private   # - `expired` tells nginx to check the "Expires" field   # - `auth` tells nginx to check the "Authorization" field
actual example	server {     gzip on;     gzip_types      text/plain application/xml;     gzip_proxied    no-cache no-store private expired auth;     gzip_min_length 1000;     ... }

Enabling Decompression

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- some clients doens't support responses with `gzip` encoding

- nginx can decompress response on the fly to accomodate such clients

- `gunzip` directive is used for decompression

    -> might not be included in Nginx opensource

    -> can be placed on same contexts as `gzip` directive

enables runtime decompression

location /storage/ {     gunzip on;     ... }

Sending Compressed Files

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Sends a compressed version of the file instead of the regular one

location / {   gzip_static on;     # - a requested /file will be sent as /file.gz to client     # - if file doesn't exist/cient doesn't support gzip,     #   Nginx sends uncompressed version     # - `gzip_static` doesn't enable on-the-fly compression;     #   it simply sends the compressed file     # - to compress content at runtime, use `gzip` directive }