View Source Bandit (Bandit v0.6.8)
Bandit is an HTTP server for Plug and WebSock 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 WebSock 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
Bandit fully supports Phoenix. Phoenix applications which use WebSockets for features such as Channels or LiveView require Phoenix 1.7 or later.
Using Bandit to host your Phoenix application couldn't be simpler:
Add Bandit as a dependency in your Phoenix application's
mix.exs
:{:bandit, ">= 0.5.10"}
Add the following to your endpoint configuration in
config/config.exs
:config :your_app, YourAppWeb.Endpoint, adapter: Bandit.PhoenixAdapter
That's it! You should now see messages at startup indicating that Phoenix is using Bandit to serve your endpoint.
For more details about how to configure Bandit within Phoenix, consult the
Bandit.PhoenixAdapter
documentation.
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. 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).
config-options
Config Options
Bandit takes a number of options at startup:
plug
: The plug to handle connections. Can be specified asMyPlug
or{MyPlug, plug_opts}
display_plug
: The plug to use when describing the connection in logs. Useful for situations such as Phoenix code reloading where you have a 'wrapper' plug but wish to refer to the connection by the endpoint namescheme
: One of:http
or:https
. If:https
is specified, you will need to specifycertfile
andkeyfile
in thetransport_options
subsection ofoptions
.options
: Options to pass toThousandIsland
. For an exhaustive list of options see theThousandIsland
documentation, however some common options are:port
: The port to bind to. Defaults to 4000num_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 10read_timeout
: How long to wait for data from the client before timing out and closing the connection, specified in milliseconds. Defaults to15_000
millisecondstransport_module
: The name of the module which provides basic socket functions. This overrides any value set forscheme
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
websocket-support
WebSocket Support
Bandit supports upgrading HTTP requests to WebSocket connections via
the use of the Plug.Conn.upgrade_adapter/3
function, called with :websocket
as the second
argument. Applications should validate that the connection represents a valid WebSocket request
before calling this function (Bandit will validate the connection as part of the upgrade
process, but does not provide any capacity for an application to be notified if the upgrade is
not successful). If an application wishes to negotiate WebSocket subprotocols or otherwise set
any response headers, it should do so before calling Plug.Conn.upgrade_adapter/3
.
The third argument to Plug.Conn.upgrade_adapter/3
defines the details of how Bandit should
handle the WebSocket connection, and must take the form {handler, handler_opts, connection_opts}
, where values are as follows:
handler
is a module which implements theWebSock
APIhandler_opts
is an arbitrary term which will be passed as the argument toWebSock.init/1
connection_opts
is a keyword list which consists of zero or more of the following options:timeout
: The number of milliseconds to wait after no client data is received before closing the connection. Defaults to60_000
compress
: Whether or not to accept negotiation of a compression extension with the client. Defaults tofalse
fullsweep_after
: The maximum number of garbage collections before forcing a full sweep of the socket process. You can set it to0
to force more frequent cleanups of your websocket transport processes. Setting this option requires Erlang/OTP 24
Link to this section Summary
Functions
Starts a Bandit server using the provided arguments. See "Config Options' above for specific options to pass to this function.
Link to this section Types
A Plug definition
Link to this section Functions
@spec child_spec(keyword()) :: Supervisor.child_spec()
Starts a Bandit server using the provided arguments. See "Config Options' above for specific options to pass to this function.