Bandit is an HTTP server for Plug and Sock apps.

As an HTTP server, Bandit's primary goal is to act as 'glue' between client connections managed by Thousand Island and application code defined via the Plug and/or Sock APIs. As such there really isn't a whole lot of user-visible surface area to Bandit, and as a consequence the API documentation presented here is somewhat sparse. This is by design! Bandit is intended to 'just work' in almost all cases; the only thought users typically have to put into Bandit comes in the choice of which options (if any) they would like to change when starting a Bandit server. The sparseness of the Bandit API should not be taken as an indicator of the comprehensiveness or robustness of the project.

using-bandit-with-phoenix

Using Bandit With Phoenix

Note that as of the 0.5.x branch Bandit supports Phoenix applications which use HTTP(S). Phoenix applications which use WebSockets for features such as Channels or LiveView are not yet supported (though this support is coming soon!).

That having been said, using Bandit to host your Phoenix application couldn't be simpler:

1. Add Bandit as a dependency in your Phoenix application's mix.exs:

       {:bandit, ">= 0.5.0"}
       ```

2. Add the following to your endpoint configuration in config/config.exs:

        config :your_app, YourAppWeb.Endpoint,
          adapter: Bandit.PhoenixAdapter
        ```

3. That's it! You should now see messages at startup indicating that Phoenix is using Bandit to serve your endpoint.

using-bandit-with-plug-applications

Using Bandit With Plug Applications

Using Bandit to host your own Plug is very straightforward. Assuming you have a Plug module implemented already, you can host it within Bandit by adding something similar to the following to your application's Application.start/2 function:

def start(_type, _args) do
  children = [
    {Bandit, plug: MyApp.MyPlug, scheme: :http, options: [port: 4000]}
  ]

  opts = [strategy: :one_for_one, name: MyApp.Supervisor]
  Supervisor.start_link(children, opts)
end

For details about writing Plug based applications, consult the excellent Plug documentation for plenty of examples & tips to get started. Note that while Bandit supports the complete Plug API & should work correctly with any Plug-based application. If you encounter errors using Bandit your Plug app, please do get in touch by filing an issue on the Bandit GitHub project (especially if the error does not occur with another HTTP server such as Cowboy).

using-bandit-with-sock-applications

Using Bandit With Sock Applications

TBD

config-options

Config Options

Bandit takes a number of options at startup:

• plug: The plug to handle connections. Can be specified as MyPlug or {MyPlug, plug_opts}
• sock: The sock to handle WebSocket connections. Can be specified as MySock or {MySock, sock_opts}. Optional.
• scheme: One of :http or :https. If :https is specified, you will need to specify certfile and keyfile in the transport_options subsection of options.
• options: Options to pass to ThousandIsland. For an exhaustive list of options see the ThousandIsland documentation, however some common options are:
  • port: The port to bind to. Defaults to 4000
  • num_acceptors: The number of acceptor processes to run. This is mostly a performance tuning knob and can usually be left at the default value of 10
  • read_timeout: How long to wait for data from the client before timing out and closing the connection, specified in milliseconds. Defaults to 15_000 milliseconds
  • transport_module: The name of the module which provides basic socket functions. This overrides any value set for scheme and is intended for cases where control over the socket at a fundamental level is needed.
  • transport_options: A keyword list of options to be passed into the transport socket's listen function

setting-up-an-https-server

Setting up an HTTPS Server

By far the most common stumbling block encountered with configuration involves setting up an HTTPS server. Bandit is comparatively easy to set up in this regard, with a working example looking similar to the following:

def start(_type, _args) do
  bandit_options = [
    port: 4000,
    transport_options: [
      certfile: Path.join(__DIR__, "path/to/cert.pem"),
      keyfile: Path.join(__DIR__, "path/to/key.pem")
    ]
  ]

  children = [
    {Bandit, plug: MyApp.MyPlug, scheme: :https, options: bandit_options}
  ]

  opts = [strategy: :one_for_one, name: MyApp.Supervisor]
  Supervisor.start_link(children, opts)
end