This plug generates shallow ETags.

Shallow means that it uses the whole response to generate the ETag and does not care about the specific content of each response. It is not context sensitive. For a deep (speak context sensitive) generation of ETags you can take a look at Phoenix ETag.

NOTE: While this plug may seem stale, it's just stable. There is nothing else to do, it "just works". As such don't be afraid to use it in production. 🙂

The plug can be installed by adding etag_plug to your list of dependencies in mix.exs:

def deps do
  [
    {:etag_plug, "~> 1.0"}
  ]
end

Documentation can be found at: https://hexdocs.pm/etag_plug

You can simply use the plug without any configuration, it then defaults to the configuration as specified in the "Configuration" section.

plug ETag.Plug

You can also provide a number of options, see the "Configuration" section for details.

plug ETag.Plug,
  generator: MyCustomGenerator,
  methods: ["GET", "HEAD"],
  status_codes: [:ok, 201, :not_modified]

A full configuration equal to the defaults could look like this:

config :etag_plug,
  generator: ETag.Generator.SHA1,
  methods: ["GET"],
  status_codes: [200]

Each of these options is explained in detail below.

Expects a module implementing the ETag.Generator behaviour. The plug ships with a number of "default" generators:

• ETag.Generator.MD5
• ETag.Generator.SHA1
• ETag.Generator.SHA512

Default: Application.get_env(:etag_plug, :generator, ETag.Generator.SHA1)

Expects a list of strings, describing the HTTP methods for which ETags should be generated and evaluated.

Default: Application.get_env(:etag_plug, :methods, ["GET"])

Expects an enumerable of integers (or status atoms) which define the statuses for which ETags should be handled and generated.

Default: Application.get_env(:etag_plug, :status_codes, [200])