ngx_http_slice_module

This module can be thought out as a reverse byte-range request header. It's main utility is to allow Nginx to slice a big file in small pieces (byte-ranges) while permitting to use on-the-fly gzip compression.

A typical example is for allowing someone to download a large video file while keeping the bandwith usage minimal. This might also be used as device for selling a video file by pieces where each link points to different zones of the file splitted by file ranges.

Other use would be to use a generic CSS file and use only part of it for each section of a site. Granted that byte-range slicing isn't the most intuitive for such.

Note also that using arguments is more useful than byte-ranges in the sense that they can be set in a normal link, while byte ranges require a special HTTP header.

Examples

location ^~ /video-dump/ {
    slice; # enable slicing
    slice_start_arg s;
    slice_end_arg e;
}

So we would request the first 1k of the file like this:

http://example.com/video-dump/large_vid.mp4?s=0&e=1024

Notice s=0, start at 0 and e=1024, stop at 1024 bytes (1k).

Directives

slice context: location

It enables the content slicing in a given location.

slice_arg_begin string default: begin context: http, server, location

Defines the argument that defines the request range of bytes start.

slice_arg_end string default: end context: http, server, location

Defines the argument that defines the request range of bytes end. slice_header string context: http, server, location

Defines the string to be used as the header of each slice being

served by Nginx. slice_footer string context: http, server, location

Defines the string to be used as the footer of each slice being served by Nginx.

slice_header_first on | off default: on context: http, server, location

If set to off and when requesting the first byte of the file do not serve the header.

This directive is particularly useful to differentiate the first slice from the remaining slices. The first slice is the one which has no header.

slice_footer_last on | off default: on context: http, server, location

If set to off and when requesting the last byte of the file do not serve the header.

This directive is particularly useful to differentiate the last slice from the remaining slices. The last slice is the one which has no footer.

Here's some examples that explore all the options.

Serve a huge DB file while sending headers except on the first slice

location ^~ /dbdumps/ {
    slice; # enable slicing
    slice_start_arg first;
    slice_end_arg last;
    slice_header '-- **db-slice-start**';
    slice_header_first off;
}

Then a request like this:

http://example.com/dbdumps/somedb.sql?first=0&last=1048576

Send the first 1M and skip the -- **db-slice-start** header.

Serve a huge DB file while sending headers except on the first slice

location ^~ /dbdumps/ {
    slice; # enable slicing
    slice_start_arg first;
    slice_end_arg last;
    slice_header '-- **db-slice-start**';
    slice_header_first off;
    slice_footer '-- **db-slice-end**';
}

This differs from the previous in the sense that it sends a footer.

Serve a huge DB file while sending headers except on the first slice and send footer except on the last slice

location ^~ /dbdumps/ {
    slice; # enable slicing
    slice_start_arg first;
    slice_end_arg last;
    slice_header '-- **db-slice-start**';
    slice_header_first off;
    slice_footer '-- **db-slice-end**';
    slice_footer_last off;
}

Then a request like this:

http://example.com/dbdumps/somedb.sql?first=0&last=1048576

Send the first 1M and skip the -- **db-slice-start** header.

If the file is 200MB, we get the last slice with:

http://example.com/dbdumps/somedb.sql?first=208666624&last=209715200

this last slice has no footer.