PlugCaisson

An Elixir Plug.Parsers body reader that supports compressed payloads. Supports gzip, brotli, and more.

A caisson is an geoengineering structure used to work on foundations of bridges and piers. Due to pressurised environment in the caisson (required to keep water out of it (as it has no bottom) people can get decompression sickness, also known as caisson disease.

Installation

Add :plug_caisson to dependencies in mix.exs:

def deps do
  [
    {:plug_caisson, "~> 0.2.0"},
    # optional, for brotli support
    {:brotli, "~> 0.3.2"},
    # optional, for zstd support
    {:ezstd, "~> 1.0"},
  ]
end

And then add {PlugCaisson, :read_body, []} as a :body_reader to your Plug.Parsers:

plug Plug.Parsers,
  parsers: [:urlencoded, :json],
  body_reader: {PlugCaisson, :read_body, []},
  length: 8_000_000

All options passed to the plug are forwarded to Plug.Conn.read_body/2.

Supported algorithms

• gzip - GNU zip - most common compression algorithm used in HTTP - RFC 1952
• deflate - DEFLATE compressed data (RFC 1951) wrapped in Zlib data format (RFC 1950)
• br (requires optional :brotli dependency) - Brotli algorithm developed by Google and supported by most browsers nowadays - RFC 7932
• zstd (requires optional :ezstd dependency)[^1] - Zstandard algorithm developed by Meta (Facebook) which provides faster compression/decompression times than Brotli, but worse compression ratio - RFC 8478

[^1]:

Do not support streaming decoding yet, because of lack support for such
flow upstream, see [ezstd#11](https://github.com/silviucpp/ezstd/issues/11)