Unbrotli

The unbrotli module is designed for unpacking responses from the backend that use Brotli compression (Content-Encoding: br) for clients that do not support this compression method. This is particularly useful in cases where storing data in compressed form on the backend saves space.

Directives

The module provides the following directives:

• unbrotli – similar to gunzip.

• unbrotli_buffers – similar to gunzip_buffers.

Loading the Module

To use the module, it must be loaded in the context of main{}:

load_module modules/ngx_http_unbrotli_filter_module.so;

Configuration Example

server {
    listen 80 default_server;
    location / {
        root  /usr/share/angie/html;
        index index.html;
    }

    location /storage {
        unbrotli on;
        proxy_pass http://127.0.0.1:8080;
    }
}

# Backend
server {
    listen 8080;
    location /storage {
        root   /usr/share/angie;
        rewrite ^(.*)$ $1.br break;  # Return the compressed file with .br suffix
        add_header Content-Encoding br; # Indicate Brotli compression in the response header
    }
}

Demonstration

Let's place the compressed test file war-and-peace.txt.br:

$ ls -l /usr/share/angie/storage/
total 2292
-rw-r--r-- 1 root root 1115616 Feb 27 16:10 war-and-peace.txt.br

If the client supports Brotli, it will receive the compressed file without decompression:

$ curl -s -H 'Accept-Encoding: br' -o tmp/war-and-peace.txt localhost/storage/war-and-peace.txt

$ ls -l tmp/
total 1092
-rw-r--r-- 1 asv asv 1115616 Feb 27 16:36 war-and-peace.txt

If the client does not support Brotli, the unbrotli module will decompress the file on the server before sending:

$ curl -s -o tmp/war-and-peace.txt localhost/storage/war-and-peace.txt

$ ls -l tmp/
total 3284
-rw-r--r-- 1 asv asv 3359405 Feb 27 16:39 war-and-peace.txt

The file was decompressed by the server before being sent to the client.

Additional Information

Detailed documentation and source code are available at: clyfish/ngx_unbrotli.